Improve shader version selection

glow/src/shader/compatibility/quad.frag

@@ -1,5 +1,10 @@
-#version 100
+#ifdef GL_ES
+#ifdef GL_FRAGMENT_PRECISION_HIGH
+precision highp float;
+#else
 precision mediump float;
+#endif
+#endif
 
 uniform float u_ScreenHeight;
 
@@ -10,7 +15,7 @@ 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)
+float _distance(vec2 frag_coord, vec2 position, vec2 size, float radius)
 {
     // TODO: Try SDF approach: https://www.shadertoy.com/view/wd3XRN
     vec2 inner_size = size - vec2(radius, radius) * 2.0;

glow/src/shader/compatibility/quad.vert

@@ -1,5 +1,3 @@
-#version 100
-
 uniform mat4 u_Transform;
 uniform float u_Scale;
 

glow/src/shader/compatibility/triangle.frag

@@ -1,8 +0,0 @@
-#version 100
-precision mediump float;
-
-varying vec4 v_Color;
-
-void main() {
-    gl_FragColor = v_Color;
-}

glow/src/shader/compatibility/triangle.vert

@@ -1,13 +0,0 @@
-#version 100
-
-uniform mat4 u_Transform;
-
-attribute vec2 i_Position;
-attribute vec4 i_Color;
-
-varying vec4 v_Color;
-
-void main() {
-    v_Color = i_Color;
-    gl_Position = u_Transform * vec4(i_Position, 0.0, 1.0);
-}