blob: 008d88a4d5b6eecd4ea488c1698f43f50929266e [file] [log] [blame] [edit]
struct Uniforms {
u_scale : vec2<f32>;
u_offset : vec2<f32>;
};
[[binding(0), group(0)]] var<uniform> uniforms : Uniforms;
struct VertexOutputs {
[[location(0)]] texcoords : vec2<f32>;
[[builtin(position)]] position : vec4<f32>;
};
[[stage(vertex)]] fn vs_main(
[[builtin(vertex_index)]] VertexIndex : u32
) -> VertexOutputs {
var texcoord = array<vec2<f32>, 3>(
vec2<f32>(-0.5, 0.0),
vec2<f32>( 1.5, 0.0),
vec2<f32>( 0.5, 2.0));
var output : VertexOutputs;
output.position = vec4<f32>((texcoord[VertexIndex] * 2.0 - vec2<f32>(1.0, 1.0)), 0.0, 1.0);
// Y component of scale is calculated by the copySizeHeight / textureHeight. Only
// flipY case can get negative number.
var flipY = uniforms.u_scale.y < 0.0;
// Texture coordinate takes top-left as origin point. We need to map the
// texture to triangle carefully.
if (flipY) {
// We need to get the mirror positions(mirrored based on y = 0.5) on flip cases.
// Adopt transform to src texture and then mapping it to triangle coord which
// do a +1 shift on Y dimension will help us got that mirror position perfectly.
output.texcoords = (texcoord[VertexIndex] * uniforms.u_scale + uniforms.u_offset) *
vec2<f32>(1.0, -1.0) + vec2<f32>(0.0, 1.0);
} else {
// For the normal case, we need to get the exact position.
// So mapping texture to triangle firstly then adopt the transform.
output.texcoords = (texcoord[VertexIndex] *
vec2<f32>(1.0, -1.0) + vec2<f32>(0.0, 1.0)) *
uniforms.u_scale + uniforms.u_offset;
}
return output;
}
[[binding(1), group(0)]] var mySampler: sampler;
[[binding(2), group(0)]] var myTexture: texture_2d<f32>;
[[stage(fragment)]] fn fs_main(
[[location(0)]] texcoord : vec2<f32>
) -> [[location(0)]] vec4<f32> {
// Clamp the texcoord and discard the out-of-bound pixels.
var clampedTexcoord =
clamp(texcoord, vec2<f32>(0.0, 0.0), vec2<f32>(1.0, 1.0));
if (!all(clampedTexcoord == texcoord)) {
discard;
}
var srcColor = textureSample(myTexture, mySampler, texcoord);
// Swizzling of texture formats when sampling / rendering is handled by the
// hardware so we don't need special logic in this shader. This is covered by tests.
return srcColor;
}