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use std::rc::Rc; use crate::error::Result; use crate::graphics::{DrawParams, FilterMode, Texture}; use crate::platform::{RawCanvas, RawRenderbuffer}; use crate::Context; use super::ImageData; /// A builder for creating advanced canvas configurations. /// /// By default, Tetra's canvases are fairly simple - they just provide a [`Texture`] that you /// can render things to. However, they can also be configured with extra features via this /// builder, such as multisampling and additional buffers. #[derive(Debug, Clone)] pub struct CanvasBuilder { width: i32, height: i32, samples: u8, stencil_buffer: bool, } impl CanvasBuilder { /// Creates a new canvas builder, which can be used to create a canvas with multisampling and/or /// additional buffers. /// /// You can also use [`Canvas::builder`] as a shortcut for this, if you want /// to avoid the extra import. pub fn new(width: i32, height: i32) -> CanvasBuilder { CanvasBuilder { width, height, samples: 0, stencil_buffer: false, } } /// Sets the level of multisample anti-aliasing to use. /// /// The number of samples that can be used varies between graphics cards - `2`, `4` and `8` are reasonably /// well supported. When set to `0` (the default), no multisampling will be used. /// /// # Resolving /// /// In order to actually display a multisampled canvas, it first has to be downsampled (or 'resolved'). This is /// done automatically once you switch to a different canvas/the backbuffer. Until this step takes place, /// your rendering will *not* be reflected in the canvas' underlying [`texture`](Canvas::texture) (and by /// extension, in the output of [`draw`](Canvas::draw) and [`get_data`](Canvas::get_data)). pub fn samples(&mut self, samples: u8) -> &mut CanvasBuilder { self.samples = samples; self } /// Sets whether the canvas should have a stencil buffer. /// /// Setting this to `true` allows you to use stencils while rendering to the canvas, at the cost /// of some extra video RAM usage. pub fn stencil_buffer(&mut self, enabled: bool) -> &mut CanvasBuilder { self.stencil_buffer = enabled; self } /// Builds the canvas. /// /// # Errors /// /// * [`TetraError::PlatformError`](crate::TetraError::PlatformError) will be returned if the underlying /// graphics API encounters an error. pub fn build(&self, ctx: &mut Context) -> Result<Canvas> { let attachments = ctx.device.new_canvas( self.width, self.height, ctx.graphics.default_filter_mode, self.samples, self.stencil_buffer, )?; Ok(Canvas { handle: Rc::new(attachments.canvas), texture: Texture::from_raw(attachments.color, ctx.graphics.default_filter_mode), stencil_buffer: attachments.depth_stencil.map(Rc::new), multisample: attachments.multisample_color.map(Rc::new), }) } } /// A texture that can be used for off-screen rendering. /// /// This is sometimes referred to as a 'render texture' or 'render target' in other /// frameworks. /// /// Canvases can be useful if you want to do some rendering upfront and then cache the result /// (e.g. a static background), or if you want to apply transformations/shaders to multiple /// things simultaneously. /// /// # Performance /// /// Creating a `Canvas` is a relatively expensive operation. If you can, store them in your /// [`State`](crate::State) struct rather than recreating them each frame. /// /// Cloning a `Canvas` is a very cheap operation, as the underlying data is shared between the /// original instance and the clone via [reference-counting](https://doc.rust-lang.org/std/rc/struct.Rc.html). /// This does mean, however, that updating a `Canvas` (for example, changing its filter mode) will also /// update any other clones of that `Canvas`. /// /// # Examples /// /// The [`canvas`](https://github.com/17cupsofcoffee/tetra/blob/main/examples/canvas.rs) /// example demonstrates how to draw to a canvas, and then draw that canvas to /// the screen. #[derive(Debug, Clone, PartialEq)] pub struct Canvas { pub(crate) handle: Rc<RawCanvas>, pub(crate) texture: Texture, pub(crate) stencil_buffer: Option<Rc<RawRenderbuffer>>, pub(crate) multisample: Option<Rc<RawRenderbuffer>>, } impl Canvas { /// Creates a new canvas, with the default settings (no multisampling, no additional buffers). /// /// # Errors /// /// * [`TetraError::PlatformError`](crate::TetraError::PlatformError) will be returned if the underlying /// graphics API encounters an error. pub fn new(ctx: &mut Context, width: i32, height: i32) -> Result<Canvas> { CanvasBuilder::new(width, height).build(ctx) } /// Creates a new canvas builder, which can be used to create a canvas with multisampling and/or /// additional buffers. pub fn builder(width: i32, height: i32) -> CanvasBuilder { CanvasBuilder::new(width, height) } /// Creates a new canvas, with the specified level of multisample anti-aliasing. /// /// The number of samples that can be used varies between graphics cards - `2`, `4` and `8` are reasonably /// well supported. When set to `0` (the default), no multisampling will be used. /// /// # Resolving /// /// In order to actually display a multisampled canvas, it first has to be downsampled (or 'resolved'). This is /// done automatically once you switch to a different canvas/the backbuffer. Until this step takes place, /// your rendering will *not* be reflected in the canvas' underlying [`texture`](Self::texture) (and by /// extension, in the output of [`draw`](Self::draw) and [`get_data`](Self::get_data)). /// /// # Errors /// /// * [`TetraError::PlatformError`](crate::TetraError::PlatformError) will be returned if the underlying /// graphics API encounters an error. #[deprecated(since = "0.6.4", note = "use Canvas::builder instead")] pub fn multisampled(ctx: &mut Context, width: i32, height: i32, samples: u8) -> Result<Canvas> { CanvasBuilder::new(width, height) .samples(samples) .build(ctx) } /// Draws the canvas to the screen (or to another canvas, if one is enabled). pub fn draw<P>(&self, ctx: &mut Context, params: P) where P: Into<DrawParams>, { self.texture.draw(ctx, params) } /// Returns the width of the canvas. pub fn width(&self) -> i32 { self.texture.width() } /// Returns the height of the canvas. pub fn height(&self) -> i32 { self.texture.height() } /// Returns the size of the canvas. pub fn size(&self) -> (i32, i32) { self.texture.size() } /// Returns the filter mode being used by the canvas. pub fn filter_mode(&self) -> FilterMode { self.texture.filter_mode() } /// Sets the filter mode that should be used by the canvas. pub fn set_filter_mode(&mut self, ctx: &mut Context, filter_mode: FilterMode) { self.texture.set_filter_mode(ctx, filter_mode); } /// Gets the canvas' data from the GPU. /// /// This can be useful if you need to do some image processing on the CPU, /// or if you want to output the image data somewhere. This is a fairly /// slow operation, so avoid doing it too often! /// /// If this is the currently active canvas, you should unbind it or call /// [`graphics::flush`](super::flush) before calling this method, to ensure all /// pending draw calls are reflected in the output. Similarly, if the canvas is /// multisampled, it must be [resolved](#resolving) before /// changes will be reflected in this method's output. pub fn get_data(&self, ctx: &mut Context) -> ImageData { self.texture.get_data(ctx) } /// Writes RGBA pixel data to a specified region of the canvas. /// /// This method requires you to provide enough data to fill the target rectangle. /// If you provide too little data, an error will be returned. /// If you provide too much data, it will be truncated. /// /// If you want to overwrite the entire canvas, the `replace_data` method offers a /// more concise way of doing this. /// /// # Errors /// /// * [`TetraError::NotEnoughData`](crate::TetraError::NotEnoughData) will be returned /// if not enough data is provided to fill the target rectangle. This is to prevent /// the graphics API from trying to read uninitialized memory. /// /// # Panics /// /// Panics if any part of the target rectangle is outside the bounds of the canvas. pub fn set_data( &self, ctx: &mut Context, x: i32, y: i32, width: i32, height: i32, data: &[u8], ) -> Result { self.texture.set_data(ctx, x, y, width, height, data) } /// Overwrites the entire canvas with new RGBA pixel data. /// /// This method requires you to provide enough data to fill the canvas. /// If you provide too little data, an error will be returned. /// If you provide too much data, it will be truncated. /// /// If you only want to write to a subsection of the canvas, use the `set_data` /// method instead. /// /// # Errors /// /// * [`TetraError::NotEnoughData`](crate::TetraError::NotEnoughData) will be returned /// if not enough data is provided to fill the target rectangle. This is to prevent /// the graphics API from trying to read uninitialized memory. pub fn replace_data(&self, ctx: &mut Context, data: &[u8]) -> Result { self.texture.replace_data(ctx, data) } /// Returns a reference to the canvas' underlying texture. /// /// If this is the currently active canvas, you may want to unbind it or call /// [`graphics::flush`](super::flush) before trying to access the underlying /// texture data, to ensure all pending draw calls are completed. Similarly, /// if the canvas is multisampled, it must be [resolved](#resolving) /// before changes will be reflected in the texture. pub fn texture(&self) -> &Texture { &self.texture } }