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//! # GPU geometries. //! //! Tessellations (i.e. [`Tess`]) represent geometric information stored on GPU. They are at the //! heart of any render, should it be 2D, 3D or even more exotic configuration. Please familiarize //! yourself with the tessellation abstractions before going on. //! //! # Tessellation primitive //! //! Currently, several kinds of tessellation are supported: //! //! - [`Mode::Point`]; _point clouds_. //! - [`Mode::Line`]; _lines_. //! - [`Mode::LineStrip`]; _line strips_, which are lines connected between them to create a single, //! long line. //! - [`Mode::Triangle`]; _triangles_. //! - [`Mode::TriangleFan`]; _triangle fans_, a way of connecting triangles. //! - [`Mode::TriangleStrip`]; _triangle strips_, another way of connecting triangles. //! - [`Mode::Patch`]; _patches_, the primitives that tessellation shaders operate on. //! //! Those kinds of tessellation are designated by the [`Mode`] type. You will also come across the //! name of _primitive mode_ to designate such an idea. //! //! # Tessellation creation //! //! Creation is done via the [`TessBuilder`] type, using the _builder_ pattern. Once you’re done //! with configuring everything, you can generate the tessellation and get a [`Tess`] object. //! //! [`Tess`] represents data on the GPU and can be thought of as an access to the actual data, a bit //! in the same way as a [`Vec`] is just a small data structure that represents an access to a //! much bigger memory area. //! //! # Tessellation render //! //! In order to render a [`Tess`], you have to use a [`TessSlice`] object. You’ll be able to use //! that object in *pipelines*. See the [pipeline] module for further details. //! //! [`Mode`]: crate::tess::Mode //! [`Mode::Point`]: crate::tess::Mode::Point //! [`Mode::Line`]: crate::tess::Mode::Line //! [`Mode::LineStrip`]: crate::tess::Mode::LineStrip //! [`Mode::Triangle`]: crate::tess::Mode::Triangle //! [`Mode::TriangleFan`]: crate::tess::Mode::TriangleFan //! [`Mode::TriangleStrip`]: crate::tess::Mode::TriangleStrip //! [`Mode::Patch`]: crate::tess::Mode::Patch //! [`BufferSlice`]: crate::buffer::BufferSlice //! [`BufferSliceMut`]: crate::buffer::BufferSliceMut //! [`Tess`]: crate::tess::Tess //! [`Tess::as_slice`]: crate::tess::Tess::as_slice //! [`Tess::as_slice_mut`]: crate::tess::Tess::as_slice_mut //! [`TessBuilder`]: crate::tess::TessBuilder //! [`TessSlice`]: crate::tess::TessSlice //! [pipeline]: crate::pipeline #[cfg(feature = "std")] use std::fmt; #[cfg(feature = "std")] use std::ops::{Range, RangeFrom, RangeFull, RangeInclusive, RangeTo, RangeToInclusive}; #[cfg(feature = "std")] use std::os::raw::c_void; #[cfg(feature = "std")] use std::ptr; use std::cell::RefCell; use std::rc::Rc; #[cfg(not(feature = "std"))] use alloc::vec::Vec; #[cfg(not(feature = "std"))] use core::fmt; #[cfg(not(feature = "std"))] use core::ops::{Range, RangeFrom, RangeFull, RangeTo}; #[cfg(not(feature = "std"))] use core::ptr; use crate::buffer::{Buffer, BufferError, BufferSlice, BufferSliceMut, RawBuffer}; use crate::context::GraphicsContext; use crate::metagl::*; use crate::state::{Bind, GraphicsState}; use crate::vertex::{ Normalized, Vertex, VertexAttribDesc, VertexAttribDim, VertexAttribType, VertexBufferDesc, VertexDesc, VertexInstancing, }; use crate::vertex_restart::VertexRestart; /// Vertices can be connected via several modes. /// /// Some modes allow for _primitive restart_. Primitive restart is a cool feature that allows to /// _break_ the building of a primitive to _start over again_. For instance, when making a curve, /// you can imagine gluing segments next to each other. If at some point, you want to start a new /// line, you have two choices: /// /// - Either you stop your draw call and make another one. /// - Or you just use the _primitive restart_ feature to ask to create another line from scratch. /// /// That feature is encoded with a special _vertex index_. You can setup the value of the _primitive /// restart index_ with [`TessBuilder::set_primitive_restart_index`]. Whenever a vertex index is set /// to the same value as the _primitive restart index_, the value is not interpreted as a vertex /// index but just a marker / hint to start a new primitive. #[derive(Copy, Clone, Debug)] pub enum Mode { /// A single point. /// /// Points are left unconnected from each other and represent a _point cloud_. This is the typical /// primitive mode you want to do, for instance, particles rendering. Point, /// A line, defined by two points. /// /// Every pair of vertices are connected together to form a straight line. Line, /// A strip line, defined by at least two points and zero or many other ones. /// /// The first two vertices create a line, and every new vertex flowing in the graphics pipeline /// (starting from the third, then) well extend the initial line, making a curve composed of /// several segments. /// /// > This kind of primitive mode allows the usage of _primitive restart_. LineStrip, /// A triangle, defined by three points. Triangle, /// A triangle fan, defined by at least three points and zero or many other ones. /// /// Such a mode is easy to picture: a cooling fan is a circular shape, with blades. /// [`Mode::TriangleFan`] is kind of the same. The first vertex is at the center of the fan, then /// the second vertex creates the first edge of the first triangle. Every time you add a new /// vertex, a triangle is created by taking the first (center) vertex, the very previous vertex /// and the current vertex. By specifying vertices around the center, you actually create a /// fan-like shape. /// /// > This kind of primitive mode allows the usage of _primitive restart_. TriangleFan, /// A triangle strip, defined by at least three points and zero or many other ones. /// /// This mode is a bit different from [`Mode::TriangleFan`]. The first two vertices define the /// first edge of the first triangle. Then, for each new vertex, a new triangle is created by /// taking the very previous vertex and the last to very previous vertex. What it means is that /// every time a triangle is created, the next vertex will share the edge that was created to /// spawn the previous triangle. /// /// This mode is useful to create long ribbons / strips of triangles. /// /// > This kind of primitive mode allows the usage of _primitive restart_. TriangleStrip, /// A general purpose primitive with _n_ vertices, for use in tessellation shaders. /// For example, `Mode::Patch(3)` represents triangle patches, so every three vertices in the /// buffer form a patch. /// If you want to employ tessellation shaders, this is the only primitive mode you can use. Patch(usize), } /// Error that can occur while trying to map GPU tessellation to host code. #[derive(Debug, Eq, PartialEq)] pub enum TessMapError { /// The CPU mapping failed due to buffer errors. VertexBufferMapFailed(BufferError), /// The CPU mapping failed due to buffer errors. IndexBufferMapFailed(BufferError), /// Vertex target type is not the same as the one stored in the buffer. VertexTypeMismatch(VertexDesc, VertexDesc), /// Index target type is not the same as the one stored in the buffer. IndexTypeMismatch(TessIndexType, TessIndexType), /// The CPU mapping failed because you cannot map an attributeless tessellation since it doesn’t /// have any vertex attribute. ForbiddenAttributelessMapping, /// The CPU mapping failed because currently, mapping deinterleaved buffers is not supported via /// a single slice. ForbiddenDeinterleavedMapping, } impl fmt::Display for TessMapError { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { match *self { TessMapError::VertexBufferMapFailed(ref e) => { write!(f, "cannot map tessellation vertex buffer: {}", e) } TessMapError::IndexBufferMapFailed(ref e) => { write!(f, "cannot map tessellation index buffer: {}", e) } TessMapError::VertexTypeMismatch(ref a, ref b) => write!( f, "cannot map tessellation: vertex type mismatch between {:?} and {:?}", a, b ), TessMapError::IndexTypeMismatch(ref a, ref b) => write!( f, "cannot map tessellation: index type mismatch between {:?} and {:?}", a, b ), TessMapError::ForbiddenAttributelessMapping => { f.write_str("cannot map an attributeless buffer") } TessMapError::ForbiddenDeinterleavedMapping => { f.write_str("cannot map a deinterleaved buffer as interleaved") } } } } struct VertexBuffer { /// Indexed format of the buffer. fmt: VertexDesc, /// Internal buffer. buf: RawBuffer, } /// Build tessellations the easy way. /// /// This type allows you to create [`Tess`] by specifying piece-by-piece what the tessellation is /// made of. Several situations and configurations are supported. /// /// # Specifying vertices /// /// If you want to create a [`Tess`] holding vertices without anything else, you want to use the /// [`TessBuilder::add_vertices`]. Every time that function is called, a _vertex buffer_ is /// virtually allocated for your tessellation, which gives you three possibilities: /// /// ## 1. Attributeless [`Tess`] /// /// If you don’t call that function, you end up with an _attributeless_ tessellation. Such a /// tessellation has zero memory allocated to vertices. Instead, when invoking a _vertex shader_, /// the vertices must be created on the fly _inside_ the vertex shader directly. /// /// ## 2. Interleaved [`Tess`] /// /// If you call that function once, you have a single _vertex buffer_ allocated, which either /// gives you a 1-attribute tessellation, or an interleaved tessellation. Interleaved tessellation /// allows you to use a Rust `struct` (if it implements the [`Vertex`] trait) as vertex type and /// easily fetch them from a vertex shader. /// /// ## 3. Deinterleaved [`Tess`] /// /// If you call that function several times, the [`TessBuilder`] assumes you want _deinterleaved_ /// memory, which means that each patch of vertices you add is supposed to contain one type of /// deinterleaved vertex attributes. A coherency check is done by the [`TessBuilder`] to ensure /// the vertex data is correct. /// /// # Specifying indices /// /// By default, vertices are picked in the order you specify them in the vertex buffer(s). If you /// want more control on the order, you can add _indices_. /// /// As soon as you provide indices, the [`TessBuilder`] will change the way [`Tess`] will fetch /// vertices. Instead of fetching the first vertex, then second, then third, etc., it will first /// fetch the first index, then the second, then third, and respectively use the value of those /// indices to fetch the actual vertices. /// /// For instance, if instead of fetching vertices `[1, 2, 3`] (which is the default) you want to /// fetch `[12, 35, 2]`, you can add the `[12, 35, 2]` indices in the [`TessBuilder`]. When /// rendering, the [`Tess`] will fetch the first index and get `12`; it will then make the first /// vertex to be fetched the 12th; then fetch the second index; get `35` and fetch the 35th vertex. /// Finally, as you might have guessed, it will fetch the third index, get `2` and then the third /// vertex to be fetched will be the second one. /// /// That feature is really important as it allows you to _factorize_ vertices: instead of /// duplicating them, you can just reuse their indices. /// /// You can have only one set of indices. See the [`TessBuilder::set_indices`] function. /// /// # Specifying vertex instancing /// /// It’s also possible to provide instancing information. Those are special vertex attributes that /// are picked on an _instance_-based information instead of _vertex number_ one. It works very /// similarly to how vertices data work, but on a per-instance bases. /// /// See the [`TessBuilder::add_instances`] function for further details. pub struct TessBuilder<'a, C> { ctx: &'a mut C, vertex_buffers: Vec<VertexBuffer>, index_buffer: Option<(RawBuffer, TessIndexType)>, restart_index: Option<u32>, mode: Mode, vert_nb: usize, instance_buffers: Vec<VertexBuffer>, inst_nb: usize, } impl<'a, C> TessBuilder<'a, C> { /// Create a new, default [`TessBuilder`]. /// /// By default, the _primitive mode_ of the building [`Tess`] is [`Mode::Point`]. pub fn new(ctx: &'a mut C) -> Self { TessBuilder { ctx, vertex_buffers: Vec::new(), index_buffer: None, restart_index: None, mode: Mode::Point, vert_nb: 0, instance_buffers: Vec::new(), inst_nb: 0, } } } impl<'a, C> TessBuilder<'a, C> where C: GraphicsContext, { /// Add vertices to be part of the tessellation. /// /// This method can be used in several ways. First, you can decide to use interleaved memory, in /// which case you will call this method only once by providing an interleaved slice / borrowed /// buffer. Second, you can opt-in to use deinterleaved memory, in which case you will have /// several, smaller buffers of borrowed data and you will issue a call to this method for all of /// them. pub fn add_vertices<V, W>(mut self, vertices: W) -> Self where W: AsRef<[V]>, V: Vertex, { let vertices = vertices.as_ref(); let vb = VertexBuffer { fmt: V::vertex_desc(), buf: Buffer::from_slice(self.ctx, vertices).into_raw(), }; self.vertex_buffers.push(vb); self } /// Add instances to be part of the tessellation. pub fn add_instances<V, W>(mut self, instances: W) -> Self where W: AsRef<[V]>, V: Vertex, { let instances = instances.as_ref(); let vb = VertexBuffer { fmt: V::vertex_desc(), buf: Buffer::from_slice(self.ctx, instances).into_raw(), }; self.instance_buffers.push(vb); self } /// Set vertex indices in order to specify how vertices should be picked by the GPU pipeline. pub fn set_indices<T, I>(mut self, indices: T) -> Self where T: AsRef<[I]>, I: TessIndex, { let indices = indices.as_ref(); // create a new raw buffer containing the indices and turn it into a vertex buffer let buf = Buffer::from_slice(self.ctx, indices).into_raw(); self.index_buffer = Some((buf, I::INDEX_TYPE)); self } /// Set the primitive mode for the building [`Tess`]. pub fn set_mode(mut self, mode: Mode) -> Self { self.mode = mode; self } /// Set the default number of vertices to be rendered. /// /// That function is not mandatory if you are not building an _attributeless_ tessellation but is /// if you are. /// /// When called while building a [`Tess`] owning at least one vertex buffer, it acts as a _default_ /// number of vertices to render and is useful when you will slice the tessellation with open /// ranges. pub fn set_vertex_nb(mut self, nb: usize) -> Self { self.vert_nb = nb; self } /// Set the default number of instances to render. /// /// `0` disables geometry instancing. pub fn set_instance_nb(mut self, nb: usize) -> Self { self.inst_nb = nb; self } /// Set the primitive restart index. The initial value is `None`, implying no primitive restart. pub fn set_primitive_restart_index(mut self, index: Option<u32>) -> Self { self.restart_index = index; self } /// Build the [`Tess`]. pub fn build(self) -> Result<Tess, TessError> { // try to deduce the number of vertices to render if it’s not specified let vert_nb = self.guess_vert_nb_or_fail()?; let inst_nb = self.guess_inst_nb_or_fail()?; self.build_tess(vert_nb, inst_nb) } /// Build a tessellation based on a given number of vertices to render by default. fn build_tess(self, vert_nb: usize, inst_nb: usize) -> Result<Tess, TessError> { let mut vao: GLuint = 0; unsafe { let mut gfx_st = self.ctx.state().borrow_mut(); let patch_vert_nb = match self.mode { Mode::Patch(nb) => nb, _ => 0, }; gl::GenVertexArrays(1, &mut vao); // force binding the vertex array so that previously bound vertex arrays (possibly the same // handle) don’t prevent us from binding here gfx_st.bind_vertex_array(vao, Bind::Forced); // add the vertex buffers into the vao for vb in &self.vertex_buffers { // force binding as it’s meaningful when a vao is bound gfx_st.bind_array_buffer(vb.buf.handle(), Bind::Forced); set_vertex_pointers(&vb.fmt) } // in case of indexed render, create an index buffer if let Some(ref index_buffer) = self.index_buffer { // force binding as it’s meaningful when a vao is bound gfx_st.bind_element_array_buffer(index_buffer.0.handle(), Bind::Forced); } // add any instance buffers, if any for vb in &self.instance_buffers { // force binding as it’s meaningful when a vao is bound gfx_st.bind_array_buffer(vb.buf.handle(), Bind::Forced); set_vertex_pointers(&vb.fmt); } let restart_index = self.restart_index; let index_state = self .index_buffer .map(move |(buffer, index_type)| IndexedDrawState { restart_index, _buffer: buffer, index_type, }); // convert to OpenGL-friendly internals and return Ok(Tess { mode: opengl_mode(self.mode), vert_nb, inst_nb, patch_vert_nb, vao, vertex_buffers: self.vertex_buffers, instance_buffers: self.instance_buffers, index_state, state: self.ctx.state().clone(), }) } } /// Guess how many vertices there are to render based on the current configuration or fail if /// incorrectly configured. fn guess_vert_nb_or_fail(&self) -> Result<usize, TessError> { if self.vert_nb == 0 { // we don’t have an explicit vertex number to render; go and guess! if let Some(ref index_buffer) = self.index_buffer { // we have an index buffer: just use its size Ok(index_buffer.0.len()) } else { // deduce the number of vertices based on the vertex buffers; they all // must be of the same length, otherwise it’s an error match self.vertex_buffers.len() { 0 => Err(TessError::AttributelessError( "attributeless render with no vertex number".to_owned(), )), 1 => Ok(self.vertex_buffers[0].buf.len()), _ => { let vert_nb = self.vertex_buffers[0].buf.len(); let incoherent = Self::check_incoherent_buffers(self.vertex_buffers.iter(), vert_nb); if incoherent { Err(TessError::LengthIncoherency(vert_nb)) } else { Ok(vert_nb) } } } } } else { // we have an explicit number of vertices to render, but we’re gonna check that number actually // makes sense if let Some(ref index_buffer) = self.index_buffer { // we have indices (indirect draw); so we’ll compare to them if index_buffer.0.len() < self.vert_nb { return Err(TessError::Overflow(index_buffer.0.len(), self.vert_nb)); } } else { let incoherent = Self::check_incoherent_buffers(self.vertex_buffers.iter(), self.vert_nb); if incoherent { return Err(TessError::LengthIncoherency(self.vert_nb)); } else if !self.vertex_buffers.is_empty() && self.vertex_buffers[0].buf.len() < self.vert_nb { return Err(TessError::Overflow( self.vertex_buffers[0].buf.len(), self.vert_nb, )); } } Ok(self.vert_nb) } } /// Check whether any vertex buffer is incoherent in its length according to the input length. fn check_incoherent_buffers<'b, B>(mut buffers: B, len: usize) -> bool where B: Iterator<Item = &'b VertexBuffer>, { !buffers.all(|vb| vb.buf.len() == len) } /// Guess how many instances there are to render based on the current configuration or fail if /// incorrectly configured. fn guess_inst_nb_or_fail(&self) -> Result<usize, TessError> { if self.inst_nb == 0 { // we don’t have an explicit instance number to render; go and guess! // deduce the number of instances based on the instance buffers; they all must be of the same // length, otherwise it’s an error match self.instance_buffers.len() { 0 => { // no instance buffer; we we’re not using instance rendering Ok(0) } 1 => Ok(self.instance_buffers[0].buf.len()), _ => { let inst_nb = self.instance_buffers[0].buf.len(); let incoherent = Self::check_incoherent_buffers(self.instance_buffers.iter(), inst_nb); if incoherent { Err(TessError::LengthIncoherency(inst_nb)) } else { Ok(inst_nb) } } } } else { // we have an explicit number of instances to render, but we’re gonna check that number // actually makes sense let incoherent = Self::check_incoherent_buffers(self.instance_buffers.iter(), self.vert_nb); if incoherent { return Err(TessError::LengthIncoherency(self.inst_nb)); } else if !self.instance_buffers.is_empty() && self.instance_buffers[0].buf.len() < self.inst_nb { return Err(TessError::Overflow( self.instance_buffers[0].buf.len(), self.inst_nb, )); } Ok(self.inst_nb) } } } /// Possible errors that might occur when dealing with [`Tess`]. #[derive(Debug)] pub enum TessError { /// Error related to attributeless tessellation and/or render. AttributelessError(String), /// Length incoherency in vertex, index or instance buffers. LengthIncoherency(usize), /// Overflow when accessing underlying buffers. Overflow(usize, usize), } /// Possible tessellation index types. #[derive(Copy, Clone, Debug, Eq, PartialEq)] pub enum TessIndexType { /// 8-bit unsigned integer. U8, /// 16-bit unsigned integer. U16, /// 32-bit unsigned integer. U32, } impl TessIndexType { fn to_glenum(self) -> GLenum { match self { TessIndexType::U8 => gl::UNSIGNED_BYTE, TessIndexType::U16 => gl::UNSIGNED_SHORT, TessIndexType::U32 => gl::UNSIGNED_INT, } } fn bytes(self) -> usize { match self { TessIndexType::U8 => 1, TessIndexType::U16 => 2, TessIndexType::U32 => 4, } } } /// Class of tessellation indexes. /// /// Values which types implement this trait are allowed to be used to index tessellation in *indexed /// draw commands*. /// /// You shouldn’t have to worry to much about that trait. Have a look at the current implementors /// for an exhaustive list of types you can use. /// /// > Implementing this trait is `unsafe`. pub unsafe trait TessIndex { /// Type of the underlying index. /// /// You are limited in which types you can use as indexes. Feel free to have a look at the /// documentation of the [`TessIndexType`] trait for further information. const INDEX_TYPE: TessIndexType; } unsafe impl TessIndex for u8 { const INDEX_TYPE: TessIndexType = TessIndexType::U8; } unsafe impl TessIndex for u16 { const INDEX_TYPE: TessIndexType = TessIndexType::U16; } unsafe impl TessIndex for u32 { const INDEX_TYPE: TessIndexType = TessIndexType::U32; } /// All the extra data required when doing indexed drawing. struct IndexedDrawState { _buffer: RawBuffer, restart_index: Option<u32>, index_type: TessIndexType, } /// GPU tessellation. /// /// GPU tessellations gather several pieces of information: /// /// - _Vertices_, which define points in space associated with _vertex attributes_, giving them /// meaningful data. Those data are then processed by a _vertex shader_ to produce more /// interesting data down the graphics pipeline. /// - _Indices_, which are used to change the order the _vertices_ are fetched to form /// _primitives_ (lines, triangles, etc.). /// - _Primitive mode_, the way vertices should be linked together. See [`Mode`] for further /// details. /// - And other information used to determine how to render such tessellations. /// /// A [`Tess`] doesn’t directly state how to render an object, it just describes its topology and /// inner construction (i.e. mesh). /// /// Constructing a [`Tess`] is not doable directly: you need to use a [`TessBuilder`] first. pub struct Tess { mode: GLenum, vert_nb: usize, inst_nb: usize, patch_vert_nb: usize, vao: GLenum, vertex_buffers: Vec<VertexBuffer>, instance_buffers: Vec<VertexBuffer>, index_state: Option<IndexedDrawState>, state: Rc<RefCell<GraphicsState>>, } impl Tess { fn render<C>(&self, ctx: &mut C, start_index: usize, vert_nb: usize, inst_nb: usize) where C: ?Sized + GraphicsContext, { let vert_nb = vert_nb as GLsizei; let inst_nb = inst_nb as GLsizei; unsafe { let mut gfx_st = ctx.state().borrow_mut(); gfx_st.bind_vertex_array(self.vao, Bind::Cached); if self.mode == gl::PATCHES { gfx_st.set_patch_vertex_nb(self.patch_vert_nb); } if let Some(index_state) = self.index_state.as_ref() { // indexed render let first = (index_state.index_type.bytes() * start_index) as *const c_void; if let Some(restart_index) = index_state.restart_index { gfx_st.set_vertex_restart(VertexRestart::On); gl::PrimitiveRestartIndex(restart_index); } else { gfx_st.set_vertex_restart(VertexRestart::Off); } if inst_nb <= 1 { gl::DrawElements( self.mode, vert_nb, index_state.index_type.to_glenum(), first, ); } else { gl::DrawElementsInstanced( self.mode, vert_nb, index_state.index_type.to_glenum(), first, inst_nb, ); } } else { // direct render let first = start_index as GLint; if inst_nb <= 1 { gl::DrawArrays(self.mode, first, vert_nb); } else { gl::DrawArraysInstanced(self.mode, first, vert_nb, inst_nb); } } } } /// Obtain a slice over the vertex buffer. /// /// This function fails if you try to obtain a buffer from an attriteless [`Tess`] or /// deinterleaved memory. pub fn as_slice<V>(&mut self) -> Result<BufferSlice<V>, TessMapError> where V: Vertex, { match self.vertex_buffers.len() { 0 => Err(TessMapError::ForbiddenAttributelessMapping), 1 => { let vb = &mut self.vertex_buffers[0]; let target_fmt = V::vertex_desc(); // costs a bit if vb.fmt != target_fmt { Err(TessMapError::VertexTypeMismatch(vb.fmt.clone(), target_fmt)) } else { vb.buf .as_slice() .map_err(TessMapError::VertexBufferMapFailed) } } _ => Err(TessMapError::ForbiddenDeinterleavedMapping), } } /// Obtain a mutable slice over the vertex buffer. /// /// This function fails if you try to obtain a buffer from an attriteless [`Tess`] or /// deinterleaved memory. pub fn as_slice_mut<V>(&mut self) -> Result<BufferSliceMut<V>, TessMapError> where V: Vertex, { match self.vertex_buffers.len() { 0 => Err(TessMapError::ForbiddenAttributelessMapping), 1 => { let vb = &mut self.vertex_buffers[0]; let target_fmt = V::vertex_desc(); // costs a bit if vb.fmt != target_fmt { Err(TessMapError::VertexTypeMismatch(vb.fmt.clone(), target_fmt)) } else { vb.buf .as_slice_mut() .map_err(TessMapError::VertexBufferMapFailed) } } _ => Err(TessMapError::ForbiddenDeinterleavedMapping), } } /// Obtain a slice over the index buffer. /// /// This function fails if you try to obtain a buffer from an attriteless [`Tess`] or if no /// index buffer is available. pub fn as_index_slice<I>(&mut self) -> Result<BufferSlice<I>, TessMapError> where I: TessIndex, { match self.index_state { Some(IndexedDrawState { ref mut _buffer, ref index_type, .. }) => { let target_fmt = I::INDEX_TYPE; if *index_type != target_fmt { Err(TessMapError::IndexTypeMismatch(*index_type, target_fmt)) } else { _buffer .as_slice() .map_err(TessMapError::IndexBufferMapFailed) } } None => Err(TessMapError::ForbiddenAttributelessMapping), } } /// Obtain a mutable slice over the index buffer. /// /// This function fails if you try to obtain a buffer from an attriteless [`Tess`] or if no /// index buffer is available. pub fn as_index_slice_mut<I>(&mut self) -> Result<BufferSliceMut<I>, TessMapError> where I: TessIndex, { match self.index_state { Some(IndexedDrawState { ref mut _buffer, ref index_type, .. }) => { let target_fmt = I::INDEX_TYPE; if *index_type != target_fmt { Err(TessMapError::IndexTypeMismatch(*index_type, target_fmt)) } else { _buffer .as_slice_mut() .map_err(TessMapError::IndexBufferMapFailed) } } None => Err(TessMapError::ForbiddenAttributelessMapping), } } /// Obtain a slice over the instance buffer. /// /// This function fails if you try to obtain a buffer from an attriteless [`Tess`] or /// deinterleaved memory. pub fn as_inst_slice<V>(&mut self) -> Result<BufferSlice<V>, TessMapError> where V: Vertex, { match self.instance_buffers.len() { 0 => Err(TessMapError::ForbiddenAttributelessMapping), 1 => { let vb = &mut self.instance_buffers[0]; let target_fmt = V::vertex_desc(); // costs a bit if vb.fmt != target_fmt { Err(TessMapError::VertexTypeMismatch(vb.fmt.clone(), target_fmt)) } else { vb.buf .as_slice() .map_err(TessMapError::VertexBufferMapFailed) } } _ => Err(TessMapError::ForbiddenDeinterleavedMapping), } } /// Obtain a mutable slice over the instance buffer. /// /// This function fails if you try to obtain a buffer from an attriteless [`Tess`] or /// deinterleaved memory. pub fn as_inst_slice_mut<V>(&mut self) -> Result<BufferSliceMut<V>, TessMapError> where V: Vertex, { match self.instance_buffers.len() { 0 => Err(TessMapError::ForbiddenAttributelessMapping), 1 => { let vb = &mut self.instance_buffers[0]; let target_fmt = V::vertex_desc(); // costs a bit if vb.fmt != target_fmt { Err(TessMapError::VertexTypeMismatch(vb.fmt.clone(), target_fmt)) } else { vb.buf .as_slice_mut() .map_err(TessMapError::VertexBufferMapFailed) } } _ => Err(TessMapError::ForbiddenDeinterleavedMapping), } } } impl Drop for Tess { fn drop(&mut self) { unsafe { self.state.borrow_mut().unbind_vertex_array(); gl::DeleteVertexArrays(1, &self.vao); } } } // Give OpenGL types information on the content of the VBO by setting vertex descriptors and pointers // to buffer memory. fn set_vertex_pointers(descriptors: &[VertexBufferDesc]) { // this function sets the vertex attribute pointer for the input list by computing: // - The vertex attribute ID: this is the “rank” of the attribute in the input list (order // matters, for short). // - The stride: this is easily computed, since it’s the size (bytes) of a single vertex. // - The offsets: each attribute has a given offset in the buffer. This is computed by // accumulating the size of all previously set attributes. let offsets = aligned_offsets(descriptors); let vertex_weight = offset_based_vertex_weight(descriptors, &offsets) as GLsizei; for (desc, off) in descriptors.iter().zip(offsets) { set_component_format(vertex_weight, off, desc); } } // Compute offsets for all the vertex components according to the alignments provided. fn aligned_offsets(descriptor: &[VertexBufferDesc]) -> Vec<usize> { let mut offsets = Vec::with_capacity(descriptor.len()); let mut off = 0; // compute offsets for desc in descriptor { let desc = &desc.attrib_desc; off = off_align(off, desc.align); // keep the current component descriptor aligned offsets.push(off); off += component_weight(desc); // increment the offset by the pratical size of the component } offsets } // Align an offset. #[inline] fn off_align(off: usize, align: usize) -> usize { let a = align - 1; (off + a) & !a } // Weight in bytes of a vertex component. fn component_weight(f: &VertexAttribDesc) -> usize { dim_as_size(f.dim) as usize * f.unit_size } fn dim_as_size(d: VertexAttribDim) -> GLint { match d { VertexAttribDim::Dim1 => 1, VertexAttribDim::Dim2 => 2, VertexAttribDim::Dim3 => 3, VertexAttribDim::Dim4 => 4, } } // Weight in bytes of a single vertex, taking into account padding so that the vertex stay correctly // aligned. fn offset_based_vertex_weight(descriptors: &[VertexBufferDesc], offsets: &[usize]) -> usize { if descriptors.is_empty() || offsets.is_empty() { return 0; } off_align( offsets[offsets.len() - 1] + component_weight(&descriptors[descriptors.len() - 1].attrib_desc), descriptors[0].attrib_desc.align, ) } // Set the vertex component OpenGL pointers regarding the index of the component (i), the stride fn set_component_format(stride: GLsizei, off: usize, desc: &VertexBufferDesc) { let attrib_desc = &desc.attrib_desc; let index = desc.index as GLuint; unsafe { match attrib_desc.ty { VertexAttribType::Floating => { gl::VertexAttribPointer( index, dim_as_size(attrib_desc.dim), opengl_sized_type(&attrib_desc), gl::FALSE, stride, ptr::null::<c_void>().add(off), ); } VertexAttribType::Integral(Normalized::No) | VertexAttribType::Unsigned(Normalized::No) | VertexAttribType::Boolean => { // non-normalized integrals / booleans gl::VertexAttribIPointer( index, dim_as_size(attrib_desc.dim), opengl_sized_type(&attrib_desc), stride, ptr::null::<c_void>().add(off), ); } _ => { // normalized integrals gl::VertexAttribPointer( index, dim_as_size(attrib_desc.dim), opengl_sized_type(&attrib_desc), gl::TRUE, stride, ptr::null::<c_void>().add(off), ); } } // set vertex attribute divisor based on the vertex instancing configuration let divisor = match desc.instancing { VertexInstancing::On => 1, VertexInstancing::Off => 0, }; gl::VertexAttribDivisor(index, divisor); gl::EnableVertexAttribArray(index); } } fn opengl_sized_type(f: &VertexAttribDesc) -> GLenum { match (f.ty, f.unit_size) { (VertexAttribType::Integral(_), 1) => gl::BYTE, (VertexAttribType::Integral(_), 2) => gl::SHORT, (VertexAttribType::Integral(_), 4) => gl::INT, (VertexAttribType::Unsigned(_), 1) | (VertexAttribType::Boolean, 1) => gl::UNSIGNED_BYTE, (VertexAttribType::Unsigned(_), 2) => gl::UNSIGNED_SHORT, (VertexAttribType::Unsigned(_), 4) => gl::UNSIGNED_INT, (VertexAttribType::Floating, 4) => gl::FLOAT, _ => panic!("unsupported vertex component format: {:?}", f), } } fn opengl_mode(mode: Mode) -> GLenum { match mode { Mode::Point => gl::POINTS, Mode::Line => gl::LINES, Mode::LineStrip => gl::LINE_STRIP, Mode::Triangle => gl::TRIANGLES, Mode::TriangleFan => gl::TRIANGLE_FAN, Mode::TriangleStrip => gl::TRIANGLE_STRIP, Mode::Patch(_) => gl::PATCHES, } } /// Tessellation slice. /// /// This type enables slicing a tessellation on the fly so that we can render patches of it. /// Typically, you can obtain a slice by using the [`TessSliceIndex`] trait (the /// [`TessSliceIndex::slice`] method) and combining it with some Rust range operators, such as /// [`..`] or [`..=`]. /// /// [`..`]: https://doc.rust-lang.org/std/ops/struct.RangeFull.html /// [`..=`]: https://doc.rust-lang.org/std/ops/struct.RangeInclusive.html #[derive(Clone)] pub struct TessSlice<'a> { /// Tessellation to render. tess: &'a Tess, /// Start index (vertex) in the tessellation. start_index: usize, /// Number of vertices to pick from the tessellation. vert_nb: usize, /// Number of instances to render. inst_nb: usize, } impl<'a> TessSlice<'a> { /// Create a tessellation render that will render the whole input tessellation with only one /// instance. pub fn one_whole(tess: &'a Tess) -> Self { TessSlice { tess, start_index: 0, vert_nb: tess.vert_nb, inst_nb: tess.inst_nb, } } /// Create a tessellation render that will render the whole input tessellation with as many /// instances as specified. pub fn inst_whole(tess: &'a Tess, inst_nb: usize) -> Self { TessSlice { tess, start_index: 0, vert_nb: tess.vert_nb, inst_nb, } } /// Create a tessellation render for a part of the tessellation starting at the beginning of its /// buffer with only one instance. /// /// The part is selected by giving the number of vertices to render. /// /// > Note: if you also need to use an arbitrary part of your tessellation (not starting at the /// > first vertex in its buffer), have a look at `TessSlice::one_slice`. /// /// # Panic /// /// Panic if the number of vertices is higher to the capacity of the tessellation’s vertex buffer. pub fn one_sub(tess: &'a Tess, vert_nb: usize) -> Self { if vert_nb > tess.vert_nb { panic!( "cannot render {} vertices for a tessellation which vertex capacity is {}", vert_nb, tess.vert_nb ); } TessSlice { tess, start_index: 0, vert_nb, inst_nb: 1, } } /// Create a tessellation render for a part of the tessellation starting at the beginning of its /// buffer with as many instances as specified. /// /// The part is selected by giving the number of vertices to render. /// /// > Note: if you also need to use an arbitrary part of your tessellation (not starting at the /// > first vertex in its buffer), have a look at `TessSlice::one_slice`. /// /// # Panic /// /// Panic if the number of vertices is higher to the capacity of the tessellation’s vertex buffer. pub fn inst_sub(tess: &'a Tess, vert_nb: usize, inst_nb: usize) -> Self { if vert_nb > tess.vert_nb { panic!( "cannot render {} vertices for a tessellation which vertex capacity is {}", vert_nb, tess.vert_nb ); } TessSlice { tess, start_index: 0, vert_nb, inst_nb, } } /// Create a tessellation render for a slice of the tessellation starting anywhere in its buffer /// with only one instance. /// /// The part is selected by giving the start vertex and the number of vertices to render. /// /// # Panic /// /// Panic if the start vertex is higher to the capacity of the tessellation’s vertex buffer. /// /// Panic if the number of vertices is higher to the capacity of the tessellation’s vertex buffer. pub fn one_slice(tess: &'a Tess, start: usize, nb: usize) -> Self { if start > tess.vert_nb { panic!( "cannot render {} vertices starting at vertex {} for a tessellation which vertex capacity is {}", nb, start, tess.vert_nb ); } if nb > tess.vert_nb { panic!( "cannot render {} vertices for a tessellation which vertex capacity is {}", nb, tess.vert_nb ); } TessSlice { tess, start_index: start, vert_nb: nb, inst_nb: 1, } } /// Create a tessellation render for a slice of the tessellation starting anywhere in its buffer /// with as many instances as specified. /// /// The part is selected by giving the start vertex and the number of vertices to render. /// /// # Panic /// /// Panic if the start vertex is higher to the capacity of the tessellation’s vertex buffer. /// /// Panic if the number of vertices is higher to the capacity of the tessellation’s vertex buffer. pub fn inst_slice(tess: &'a Tess, start: usize, nb: usize, inst_nb: usize) -> Self { if start > tess.vert_nb { panic!( "cannot render {} vertices starting at vertex {} for a tessellation which vertex capacity is {}", nb, start, tess.vert_nb ); } if nb > tess.vert_nb { panic!( "cannot render {} vertices for a tessellation which vertex capacity is {}", nb, tess.vert_nb ); } TessSlice { tess, start_index: start, vert_nb: nb, inst_nb, } } /// Render a tessellation. pub fn render<C>(&self, ctx: &mut C) where C: ?Sized + GraphicsContext, { self .tess .render(ctx, self.start_index, self.vert_nb, self.inst_nb); } } impl<'a> From<&'a Tess> for TessSlice<'a> { fn from(tess: &'a Tess) -> Self { TessSlice::one_whole(tess) } } /// The [`Tess`] slice index feature. /// /// That trait allows to use the syntax `tess.slice(_)` where `_` is one of Rust range operators: /// /// - [`..`](https://doc.rust-lang.org/std/ops/struct.RangeFull.html) for the whole range. /// - [`a .. b`](https://doc.rust-lang.org/std/ops/struct.Range.html) for a sub-range, excluding /// the right part. /// - [`a ..= b`](https://doc.rust-lang.org/std/ops/struct.RangeInclusive.html) for a sub-range, /// including the right part. /// - [`a ..`](https://doc.rust-lang.org/std/ops/struct.RangeFrom.html) for a sub-range open /// on the right part. /// - [`.. b`](https://doc.rust-lang.org/std/ops/struct.RangeTo.html) for a sub-range open on the /// left part and excluding the right part. /// - [`..= b](https://doc.rust-lang.org/std/ops/struct.RangeToInclusive.html) for a sub-range /// open on the left part and including the right part. /// /// It’s technically possible to add any kind of index type, even though not really useful so far. /// /// Additionally, you can use the `tess.inst_slice(range, inst_nb)` construct to also specify /// the render should be performed with `inst_nb` instances. pub trait TessSliceIndex<Idx> { /// Slice a tesselation object and yields a [`TessSlice`] according to the index range. fn slice(&self, idx: Idx) -> TessSlice; /// Slice a tesselation object and yields a [`TessSlice`] according to the index range with as /// many instances as specified. fn inst_slice(&self, idx: Idx, inst_nb: usize) -> TessSlice; } impl TessSliceIndex<RangeFull> for Tess { fn slice(&self, _: RangeFull) -> TessSlice { TessSlice::one_whole(self) } fn inst_slice(&self, _: RangeFull, inst_nb: usize) -> TessSlice { TessSlice::inst_whole(self, inst_nb) } } impl TessSliceIndex<RangeTo<usize>> for Tess { fn slice(&self, to: RangeTo<usize>) -> TessSlice { TessSlice::one_sub(self, to.end) } fn inst_slice(&self, to: RangeTo<usize>, inst_nb: usize) -> TessSlice { TessSlice::inst_sub(self, to.end, inst_nb) } } impl TessSliceIndex<RangeFrom<usize>> for Tess { fn slice(&self, from: RangeFrom<usize>) -> TessSlice { TessSlice::one_slice(self, from.start, self.vert_nb - from.start) } fn inst_slice(&self, from: RangeFrom<usize>, inst_nb: usize) -> TessSlice { TessSlice::inst_slice(self, from.start, self.vert_nb - from.start, inst_nb) } } impl TessSliceIndex<Range<usize>> for Tess { fn slice(&self, range: Range<usize>) -> TessSlice { TessSlice::one_slice(self, range.start, range.end - range.start) } fn inst_slice(&self, range: Range<usize>, inst_nb: usize) -> TessSlice { TessSlice::inst_slice(self, range.start, range.end - range.start, inst_nb) } } impl TessSliceIndex<RangeInclusive<usize>> for Tess { fn slice(&self, range: RangeInclusive<usize>) -> TessSlice { let start = *range.start(); let end = *range.end(); TessSlice::one_slice(self, start, end - start + 1) } fn inst_slice(&self, range: RangeInclusive<usize>, inst_nb: usize) -> TessSlice { let start = *range.start(); let end = *range.end(); TessSlice::inst_slice(self, start, end - start + 1, inst_nb) } } impl TessSliceIndex<RangeToInclusive<usize>> for Tess { fn slice(&self, to: RangeToInclusive<usize>) -> TessSlice { TessSlice::one_sub(self, to.end + 1) } fn inst_slice(&self, to: RangeToInclusive<usize>, inst_nb: usize) -> TessSlice { TessSlice::inst_sub(self, to.end + 1, inst_nb) } }