Peter M. Groen / dali-demo

// Vertex shader for a skybox

attribute mediump vec3 aPosition;  // DALi shader builtin
uniform   mediump mat4 uMvpMatrix; // DALi shader builtin

varying mediump vec3 vTexCoord;

void main()
{
  vTexCoord.x =  aPosition.x;
  vTexCoord.y = -aPosition.y; // convert to GL coords
  vTexCoord.z =  aPosition.z;

  mediump vec4 vertexPosition = vec4(aPosition, 1.0);
  vec4 clipSpacePosition = uMvpMatrix * vertexPosition;
  gl_Position = clipSpacePosition.xyww; // Writes 1.0, the maximum depth value, into the depth buffer.
                                        // This is an optimization to avoid running the fragment shader
                                        // for the pixels hidden by the scene's objects.
}