Draft fragment shader for rounded rectangles

wgpu/src/shader/quad.frag

@@ -1,9 +1,33 @@
 #version 450
 
 layout(location = 0) in vec4 v_Color;
+layout(location = 1) in vec2 v_Pos;
+layout(location = 2) in vec2 v_Scale;
 
 layout(location = 0) out vec4 o_Color;
 
-void main() {
-    o_Color = v_Color;
+float rounded(in vec2 frag_coord, in vec2 position, in vec2 size, float radius, float s)
+{
+    vec2 inner_size = size - vec2(radius, radius) * 2.0;
+    vec2 top_left = position + vec2(radius, radius);
+    vec2 bottom_right = top_left + inner_size;
+
+    vec2 top_left_distance = top_left - frag_coord;
+    vec2 bottom_right_distance = frag_coord - bottom_right;
+
+    vec2 distance = vec2(
+        max(max(top_left_distance.x, bottom_right_distance.x), 0),
+        max(max(top_left_distance.y, bottom_right_distance.y), 0)
+    );
+
+    float d = sqrt(distance.x * distance.x + distance.y * distance.y);
+
+    return 1.0 - smoothstep(radius - s, radius + s, d);
+}
+
+void main() {
+    o_Color = vec4(
+        v_Color.xyz,
+        v_Color.w * rounded(gl_FragCoord.xy, v_Pos, v_Scale, 5.0, 1.0)
+    );
 }

wgpu/src/shader/quad.vert

@@ -10,6 +10,8 @@ layout (set = 0, binding = 0) uniform Globals {
 };
 
 layout(location = 0) out vec4 o_Color;
+layout(location = 1) out vec2 o_Pos;
+layout(location = 2) out vec2 o_Scale;
 
 void main() {
     mat4 i_Transform = mat4(
@@ -20,5 +22,8 @@ void main() {
     );
 
     o_Color = i_Color;
+    o_Pos = i_Pos;
+    o_Scale = i_Scale;
+
     gl_Position = u_Transform * i_Transform * vec4(v_Pos, 0.0, 1.0);
 }