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examples/gkurve: adjust frag shader to show barycentric coordinates

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Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst 2022-05-21 12:40:29 -07:00
parent 2b2ba15332
commit ff5636c6f6
1 changed files with 13 additions and 16 deletions
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29
examples/gkurve/frag.wgsl
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@ -6,14 +6,13 @@ struct FragUniform {
@stage(fragment) fn main(
@location(0) uv: vec2<f32>,
@interpolate(linear) @location(1) bary: vec3<f32>,
@interpolate(linear) @location(1) bary: vec2<f32>,
@interpolate(flat) @location(2) triangle_index: u32,
) -> @location(0) vec4<f32> {
// Example 1: Visualize barycentric coordinates:
// return vec4<f32>(bary.x, bary.y, bary.z, 1.0);
// return vec4<f32>(0.0, bary.x, 0.0, 1.0); // bottom-left of triangle
// return vec4<f32>(0.0, bary.y, 0.0, 1.0); // bottom-right of triangle
// return vec4<f32>(0.0, bary.z, 0.0, 1.0); // top of triangle
// return vec4<f32>(bary.x, bary.y, 0.0, 1.0);
// return vec4<f32>(0.0, bary.x, 0.0, 1.0); // [1.0 (bottom-left vertex), 0.0 (bottom-right vertex)]
// return vec4<f32>(0.0, bary.y, 0.0, 1.0); // [1.0 (bottom-left vertex), 1.0 (top-right face)]
// Example 2: Render gkurve primitives
var inversion = -1.0;
@ -28,21 +27,19 @@ struct FragUniform {
inversion = 1.0;
}
// Gradients
let px = dpdx(bary.xy);
let py = dpdy(bary.xy);
// Gradients
let px = dpdx(bary.xy);
let py = dpdy(bary.xy);
// Chain rule
let fx = (2.0 * bary.x) * px.x - px.y;
let fy = (2.0 * bary.x) * py.x - py.y;
// Chain rule
let fx = (2.0 * bary.x) * px.x - px.y;
let fy = (2.0 * bary.x) * py.x - py.y;
// Signed distance
var dist = (bary.x * bary.x - bary.y) / sqrt(fx * fx + fy * fy);
// var dist = bary.z*bary.z - bary.y;
// Signed distance
var dist = (bary.x * bary.x - bary.y) / sqrt(fx * fx + fy * fy);
dist *= inversion;
dist /= 128.0;
dist /= 1.75;
dist /= 300.0;
// Border rendering.
if (dist > 0.0 && dist <= 0.1) { return vec4<f32>(1.0, 0.0, 0.0, 1.0); }