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examples/gkurve: simplify fragment shader, use barycentric coordinates

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Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
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Stephen Gutekanst 2022-05-14 12:54:53 -07:00 • committed by Stephen Gutekanst
parent 8b46f46cf8
commit af608151e9
3 changed files with 40 additions and 136 deletions
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36
examples/gkurve/main.zig
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@ -12,27 +12,31 @@ const glfw = @import("glfw");
pub const Vertex = struct {
pos: @Vector(4, f32),
uv: @Vector(2, f32),
bary: @Vector(3, f32) = .{ 0, 0, 0 },
};
// Simple triangle
pub const vertices = [_]Vertex{
.{ .pos = .{ 0, 0.5, 0, 1 }, .uv = .{ 0.5, 1 } },
.{ .pos = .{ -0.5, -0.5, 0, 1 }, .uv = .{ 0, 0 } },
.{ .pos = .{ 0.5, -0.5, 0, 1 }, .uv = .{ 1, 0 } },
.{ .pos = .{ 0, 0.5, 0, 1 }, .uv = .{ 0.5, 1 }, .bary = .{ 0, 0, 1 } },
.{ .pos = .{ -0.5, -0.5, 0, 1 }, .uv = .{ 0, 0 }, .bary = .{ 1, 0, 0 } },
.{ .pos = .{ 0.5, -0.5, 0, 1 }, .uv = .{ 1, 0 }, .bary = .{ 0, 1, 0 } },
};
// TODO: Need to ask Ayush about this, ideally we have a square window in this example because it
// would mean our triangles are not being "stretched" out which would make debugging nicer.
// For some reason this doesn't compile atm.
// pub const options = mach.Engine.Options{ .width = 512, .height = 512 };
// The uniform read by the vertex shader, it contains the matrix
// that will move vertices
const VertexUniform = struct {
mat: zm.Mat,
};
// The uniform read by the fragment shader, the points are used
// to calculate the bezier curve, and more or less coincide with uvs
// (Vec4 for alignment)
const FragUniform = struct {
points: [3]@Vector(4, f32),
// TODO use an enum? Remember that it will be casted to u32 in wgsl
type: u32,
// Padding for struct alignment to 16 bytes (minimum in WebGPU uniform).
padding: @Vector(3, f32) = undefined,
};
// TODO texture and sampler, create buffers and use an index field
// in FragUniform to tell which texture to read
@ -69,6 +73,7 @@ pub fn init(app: *App, engine: *mach.Engine) !void {
const vertex_attributes = [_]gpu.VertexAttribute{
.{ .format = .float32x4, .offset = @offsetOf(Vertex, "pos"), .shader_location = 0 },
.{ .format = .float32x2, .offset = @offsetOf(Vertex, "uv"), .shader_location = 1 },
.{ .format = .float32x3, .offset = @offsetOf(Vertex, "bary"), .shader_location = 2 },
};
const vertex_buffer_layout = gpu.VertexBufferLayout{
.array_stride = @sizeOf(Vertex),
@ -151,29 +156,12 @@ pub fn init(app: *App, engine: *mach.Engine) !void {
var frag_uniform_mapped = frag_uniform_buffer.getMappedRange(FragUniform, 0, num_instances);
const tmp_frag_ubo = [_]FragUniform{
.{
// The points correspond to the left point, middle point, right point (when viewed regularly)
// in UV coordinates
.points = [_]@Vector(4, f32){
.{ 0, 0, 0, 0 },
.{ 0.5, 1, 0, 0 },
.{ 1, 0, 0, 0 },
},
.type = 1,
},
.{
.points = [_]@Vector(4, f32){
.{ 0, 0, 0, 0 },
.{ 0.5, 1, 0, 0 },
.{ 1, 0, 0, 0 },
},
.type = 0,
},
.{
.points = [_]@Vector(4, f32){
.{ 0, 0, 0, 0 },
.{ 0.5, 1, 0, 0 },
.{ 1, 0, 0, 0 },
},
.type = 2,
},
};