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// Copyright (c) 2016 The vulkano developers
// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT
// license <LICENSE-MIT or https://opensource.org/licenses/MIT>,
// at your option. All files in the project carrying such
// notice may not be copied, modified, or distributed except
// according to those terms.
//! Configures the area of the framebuffer that pixels will be written to.
//!
//! There are two different concepts to determine where things will be drawn:
//!
//! - The viewport is the region of the image which corresponds to the vertex coordinates `-1.0` to
//! `1.0`.
//! - Any pixel outside of the scissor box will be discarded.
//!
//! In other words, modifying the viewport will stretch the image, while modifying the scissor
//! box acts like a filter.
//!
//! It is legal and sensible to use a viewport that is larger than the target image or that
//! only partially overlaps the target image.
//!
//! # Multiple viewports
//!
//! In most situations, you only need a single viewport and a single scissor box.
//!
//! If, however, you use a geometry shader, you can specify multiple viewports and scissor boxes.
//! Then in your geometry shader you can specify in which viewport and scissor box the primitive
//! should be written to. In GLSL this is done by writing to the special variable
//! `gl_ViewportIndex`.
//!
//! If you don't use a geometry shader or use a geometry shader where don't set which viewport to
//! use, then the first viewport and scissor box will be used.
//!
//! # Dynamic and fixed
//!
//! Vulkan allows four different setups:
//!
//! - The state of both the viewports and scissor boxes is known at pipeline creation.
//! - The state of viewports is known at pipeline creation, but the state of scissor boxes is
//! only known when submitting the draw command.
//! - The state of scissor boxes is known at pipeline creation, but the state of viewports is
//! only known when submitting the draw command.
//! - The state of both the viewports and scissor boxes is only known when submitting the
//! draw command.
//!
//! In all cases the number of viewports and scissor boxes must be the same.
//!
use std::ops::Range;
/// List of viewports and scissors that are used when creating a graphics pipeline object.
///
/// Note that the number of viewports and scissors must be the same.
#[derive(Debug, Clone)]
pub enum ViewportState {
/// The state is known in advance.
Fixed {
/// State of the viewports and scissors.
data: Vec<(Viewport, Scissor)>,
},
/// The state of viewports is known in advance, but the state of scissors is dynamic and will
/// be set when drawing.
FixedViewport {
/// State of the viewports.
viewports: Vec<Viewport>,
/// Sets whether the scissor count is also dynamic, or only the scissors themselves.
///
/// If set to `true`, the device API version must be at least 1.3, or the
/// [`extended_dynamic_state`](crate::device::Features::extended_dynamic_state) feature must
/// be enabled on the device.
scissor_count_dynamic: bool,
},
/// The state of scissors is known in advance, but the state of viewports is dynamic and will
/// be set when drawing.
FixedScissor {
/// State of the scissors.
scissors: Vec<Scissor>,
/// Sets whether the viewport count is also dynamic, or only the viewports themselves.
///
/// If set to `true`, the device API version must be at least 1.3, or the
/// [`extended_dynamic_state`](crate::device::Features::extended_dynamic_state) feature must
/// be enabled on the device.
viewport_count_dynamic: bool,
},
/// The state of both the viewports and scissors is dynamic and will be set when drawing.
Dynamic {
/// Number of viewports and scissors.
///
/// This is ignored if both `viewport_count_dynamic` and `scissor_count_dynamic` are `true`.
count: u32,
/// Sets whether the viewport count is also dynamic, or only the viewports themselves.
///
/// If set to `true`, the device API version must be at least 1.3, or the
/// [`extended_dynamic_state`](crate::device::Features::extended_dynamic_state) feature must
/// be enabled on the device.
viewport_count_dynamic: bool,
/// Sets whether the scissor count is also dynamic, or only the scissors themselves.
///
/// If set to `true`, the device API version must be at least 1.3, or the
/// [`extended_dynamic_state`](crate::device::Features::extended_dynamic_state) feature must
/// be enabled on the device.
scissor_count_dynamic: bool,
},
}
impl ViewportState {
/// Creates a `ViewportState` with fixed state and no viewports or scissors.
#[inline]
pub fn new() -> Self {
Self::Fixed { data: Vec::new() }
}
/// Creates a `ViewportState` with fixed state from the given viewports and scissors.
#[inline]
pub fn viewport_fixed_scissor_fixed(
data: impl IntoIterator<Item = (Viewport, Scissor)>,
) -> Self {
Self::Fixed {
data: data.into_iter().collect(),
}
}
/// Creates a `ViewportState` with fixed state from the given viewports, and matching scissors
/// that cover the whole viewport.
#[inline]
pub fn viewport_fixed_scissor_irrelevant(data: impl IntoIterator<Item = Viewport>) -> Self {
Self::Fixed {
data: data
.into_iter()
.map(|viewport| (viewport, Scissor::irrelevant()))
.collect(),
}
}
/// Creates a `ViewportState` with dynamic viewport, and a single scissor that always covers
/// the whole viewport.
#[inline]
pub fn viewport_dynamic_scissor_irrelevant() -> Self {
Self::FixedScissor {
scissors: vec![Scissor::irrelevant()],
viewport_count_dynamic: false,
}
}
/// Creates a `ViewportState` with dynamic viewports and scissors, but a fixed count.
#[inline]
pub fn viewport_dynamic_scissor_dynamic(count: u32) -> Self {
Self::Dynamic {
count,
viewport_count_dynamic: false,
scissor_count_dynamic: false,
}
}
/// Creates a `ViewportState` with dynamic viewport count and scissor count.
#[inline]
pub fn viewport_count_dynamic_scissor_count_dynamic() -> Self {
Self::Dynamic {
count: 0,
viewport_count_dynamic: true,
scissor_count_dynamic: true,
}
}
/// Returns the number of viewports and scissors.
///
/// `None` is returned if both `viewport_count_dynamic` and `scissor_count_dynamic` are `true`.
pub fn count(&self) -> Option<u32> {
Some(match *self {
ViewportState::Fixed { ref data } => data.len() as u32,
ViewportState::FixedViewport { ref viewports, .. } => viewports.len() as u32,
ViewportState::FixedScissor { ref scissors, .. } => scissors.len() as u32,
ViewportState::Dynamic {
viewport_count_dynamic: true,
scissor_count_dynamic: true,
..
} => return None,
ViewportState::Dynamic { count, .. } => count,
})
}
}
impl Default for ViewportState {
/// Returns [`ViewportState::new()`].
#[inline]
fn default() -> Self {
Self::new()
}
}
/// State of a single viewport.
// FIXME: check that:
// x + width must be less than or equal to viewportBoundsRange[0]
// y + height must be less than or equal to viewportBoundsRange[1]
#[derive(Debug, Clone, PartialEq)]
pub struct Viewport {
/// Coordinates in pixels of the top-left hand corner of the viewport.
pub origin: [f32; 2],
/// Dimensions in pixels of the viewport.
pub dimensions: [f32; 2],
/// Minimum and maximum values of the depth.
///
/// The values `0.0` to `1.0` of each vertex's Z coordinate will be mapped to this
/// `depth_range` before being compared to the existing depth value.
///
/// This is equivalents to `glDepthRange` in OpenGL, except that OpenGL uses the Z coordinate
/// range from `-1.0` to `1.0` instead.
pub depth_range: Range<f32>,
}
impl From<Viewport> for ash::vk::Viewport {
#[inline]
fn from(val: Viewport) -> Self {
ash::vk::Viewport {
x: val.origin[0],
y: val.origin[1],
width: val.dimensions[0],
height: val.dimensions[1],
min_depth: val.depth_range.start,
max_depth: val.depth_range.end,
}
}
}
/// State of a single scissor box.
// FIXME: add a check:
// Evaluation of (offset.x + extent.width) must not cause a signed integer addition overflow
// Evaluation of (offset.y + extent.height) must not cause a signed integer addition overflow
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub struct Scissor {
/// Coordinates in pixels of the top-left hand corner of the box.
pub origin: [u32; 2],
/// Dimensions in pixels of the box.
pub dimensions: [u32; 2],
}
impl Scissor {
/// Returns a scissor that, when used, will instruct the pipeline to draw to the entire
/// framebuffer no matter its size.
#[inline]
pub fn irrelevant() -> Scissor {
Scissor {
origin: [0, 0],
dimensions: [0x7fffffff, 0x7fffffff],
}
}
}
impl Default for Scissor {
#[inline]
fn default() -> Scissor {
Scissor::irrelevant()
}
}
impl From<Scissor> for ash::vk::Rect2D {
#[inline]
fn from(val: Scissor) -> Self {
ash::vk::Rect2D {
offset: ash::vk::Offset2D {
x: val.origin[0] as i32,
y: val.origin[1] as i32,
},
extent: ash::vk::Extent2D {
width: val.dimensions[0],
height: val.dimensions[1],
},
}
}
}