1#version 310 es
2#extension GL_EXT_tessellation_shader : require
3#extension GL_EXT_gpu_shader5 : require
4
5layout(triangles, equal_spacing) in;
6
7layout(location = 0) in highp vec2 in_te_position[];
8
9layout(location = 0) out mediump vec4 in_f_color;
10
11precise gl_Position;
12
13void main(void) {
14  highp vec2 pos = gl_TessCoord.x * in_te_position[0] +
15                   gl_TessCoord.y * in_te_position[1] +
16                   gl_TessCoord.z * in_te_position[2];
17
18  highp float f =
19      sqrt(3.0 * min(gl_TessCoord.x, min(gl_TessCoord.y, gl_TessCoord.z))) *
20          0.5 +
21      0.5;
22  in_f_color = vec4(gl_TessCoord * f, 1.0);
23
24  // Offset the position slightly, based on the parity of the bits in the float
25  // representation.
26  // This is done to detect possible small differences in edge vertex positions
27  // between patches.
28  uvec2 bits = floatBitsToUint(pos);
29  uint numBits = 0u;
30  for (uint i = 0u; i < 32u; i++)
31    numBits +=
32        ((bits[0] << i) & 1u) + ((bits[1] << i) & 1u);
33  pos += float(numBits & 1u) * 0.04;
34
35  gl_Position = vec4(pos, 0.0, 1.0);
36}
37