148 lines
4.2 KiB
Rust
148 lines
4.2 KiB
Rust
//! Draw triangles!
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use crate::color;
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use crate::core::{Rectangle, Transformation};
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use crate::gradient;
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use bytemuck::{Pod, Zeroable};
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/// A low-level primitive to render a mesh of triangles.
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#[derive(Debug, Clone, PartialEq)]
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pub enum Mesh {
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/// A mesh with a solid color.
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Solid {
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/// The vertices and indices of the mesh.
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buffers: Indexed<SolidVertex2D>,
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/// The [`Transformation`] for the vertices of the [`Mesh`].
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transformation: Transformation,
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/// The clip bounds of the [`Mesh`].
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clip_bounds: Rectangle,
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},
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/// A mesh with a gradient.
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Gradient {
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/// The vertices and indices of the mesh.
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buffers: Indexed<GradientVertex2D>,
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/// The [`Transformation`] for the vertices of the [`Mesh`].
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transformation: Transformation,
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/// The clip bounds of the [`Mesh`].
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clip_bounds: Rectangle,
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},
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}
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impl Mesh {
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/// Returns the indices of the [`Mesh`].
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pub fn indices(&self) -> &[u32] {
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match self {
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Self::Solid { buffers, .. } => &buffers.indices,
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Self::Gradient { buffers, .. } => &buffers.indices,
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}
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}
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/// Returns the [`Transformation`] of the [`Mesh`].
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pub fn transformation(&self) -> Transformation {
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match self {
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Self::Solid { transformation, .. }
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| Self::Gradient { transformation, .. } => *transformation,
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}
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}
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/// Returns the clip bounds of the [`Mesh`].
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pub fn clip_bounds(&self) -> Rectangle {
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match self {
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Self::Solid {
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clip_bounds,
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transformation,
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..
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}
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| Self::Gradient {
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clip_bounds,
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transformation,
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..
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} => *clip_bounds * *transformation,
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}
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}
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}
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/// A set of vertices and indices representing a list of triangles.
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#[derive(Clone, Debug, PartialEq, Eq)]
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pub struct Indexed<T> {
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/// The vertices of the mesh
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pub vertices: Vec<T>,
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/// The list of vertex indices that defines the triangles of the mesh.
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///
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/// Therefore, this list should always have a length that is a multiple of 3.
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pub indices: Vec<u32>,
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}
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/// A two-dimensional vertex with a color.
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#[derive(Copy, Clone, Debug, PartialEq, Zeroable, Pod)]
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#[repr(C)]
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pub struct SolidVertex2D {
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/// The vertex position in 2D space.
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pub position: [f32; 2],
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/// The color of the vertex in __linear__ RGBA.
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pub color: color::Packed,
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}
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/// A vertex which contains 2D position & packed gradient data.
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#[derive(Copy, Clone, Debug, PartialEq, Zeroable, Pod)]
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#[repr(C)]
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pub struct GradientVertex2D {
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/// The vertex position in 2D space.
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pub position: [f32; 2],
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/// The packed vertex data of the gradient.
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pub gradient: gradient::Packed,
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}
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/// The result of counting the attributes of a set of meshes.
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#[derive(Debug, Clone, Copy, Default)]
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pub struct AttributeCount {
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/// The total amount of solid vertices.
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pub solid_vertices: usize,
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/// The total amount of solid meshes.
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pub solids: usize,
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/// The total amount of gradient vertices.
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pub gradient_vertices: usize,
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/// The total amount of gradient meshes.
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pub gradients: usize,
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/// The total amount of indices.
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pub indices: usize,
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}
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/// Returns the number of total vertices & total indices of all [`Mesh`]es.
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pub fn attribute_count_of(meshes: &[Mesh]) -> AttributeCount {
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meshes
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.iter()
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.fold(AttributeCount::default(), |mut count, mesh| {
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match mesh {
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Mesh::Solid { buffers, .. } => {
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count.solids += 1;
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count.solid_vertices += buffers.vertices.len();
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count.indices += buffers.indices.len();
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}
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Mesh::Gradient { buffers, .. } => {
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count.gradients += 1;
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count.gradient_vertices += buffers.vertices.len();
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count.indices += buffers.indices.len();
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}
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}
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count
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})
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}
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/// A renderer capable of drawing a [`Mesh`].
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pub trait Renderer {
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/// Draws the given [`Mesh`].
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fn draw_mesh(&mut self, mesh: Mesh);
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}
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