Split quad::Pipeline into core and compatibility

glow/src/shader/compatibility/quad.frag

@@ -0,0 +1,62 @@
+#version 100
+precision mediump float;
+
+uniform float u_ScreenHeight;
+
+varying vec4 v_Color;
+varying vec4 v_BorderColor;
+varying vec2 v_Pos;
+varying vec2 v_Scale;
+varying float v_BorderRadius;
+varying float v_BorderWidth;
+
+float _distance(in vec2 frag_coord, in vec2 position, in vec2 size, float radius)
+{
+    // TODO: Try SDF approach: https://www.shadertoy.com/view/wd3XRN
+    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), 0.0),
+        max(max(top_left_distance.y, bottom_right_distance.y), 0.0)
+    );
+
+    return sqrt(distance.x * distance.x + distance.y * distance.y);
+}
+
+void main() {
+    vec2 fragCoord = vec2(gl_FragCoord.x, u_ScreenHeight - gl_FragCoord.y);
+
+    float internal_border = max(v_BorderRadius - v_BorderWidth, 0.0);
+
+    float internal_distance = _distance(
+        fragCoord,
+        v_Pos + vec2(v_BorderWidth),
+        v_Scale - vec2(v_BorderWidth * 2.0),
+        internal_border
+    );
+
+    float border_mix = smoothstep(
+        max(internal_border - 0.5, 0.0),
+        internal_border + 0.5,
+        internal_distance
+    );
+
+    vec4 mixed_color = mix(v_Color, v_BorderColor, border_mix);
+
+    float d = _distance(
+        fragCoord,
+        v_Pos,
+        v_Scale,
+        v_BorderRadius
+    );
+
+    float radius_alpha =
+        1.0 - smoothstep(max(v_BorderRadius - 0.5, 0.0), v_BorderRadius + 0.5, d);
+
+    gl_FragColor = vec4(mixed_color.xyz, mixed_color.w * radius_alpha);
+}