Implement vertex shader

QTProject/subdivision-vertex.compute

 #version 430 core
 
+#define M_PI    3.14159265358979323846
+
 layout  (local_size_x  =  1)  in;
 
 struct Vertex {
@@ -25,4 +27,19 @@ layout(std430, binding=3) writeonly buffer Output {
 };
 
 void main(){
+    unsigned int size = offsets[gl_GlobalInvocationID.x + 1] - offsets[gl_GlobalInvocationID.x];
+
+    new_vertices[gl_GlobalInvocationID.x].norm = vec3(0.0f, 0.0f, 0.0f);
+    new_vertices[gl_GlobalInvocationID.x].uv = vec2(0.0f, 0.0f);
+
+    // FIXME: size or size - 1?
+    float t = 3.0f/8.0f + 2.0f/8.0f * cos(2.0f * M_PI / (float(size) - 1.0f));
+    float alpha = 5.0f/8.0f - t * t;
+
+    vec3 pos = vec3(0.0f, 0.0f, 0.0f);
+    for (unsigned int i = 1; i < size; i++) {
+        pos += vertices[indices[offsets[gl_GlobalInvocationID.x] + i]].pos;
+    }
+
+    new_vertices[gl_GlobalInvocationID.x].pos = (1.0f - alpha) * vertices[indices[offsets[gl_GlobalInvocationID.x]]].pos + alpha / (float(size) - 1) * pos;
 }