#version 460 core

// Our SSBO added in step 4
layout(std430, binding = 0) restrict readonly buffer vertexPullBuffer
{
	uint packedMeshData[]; // Contains packed data for our vertices
};

in uint _meshdat;
out vec2 UV;
out vec3 FragmentPos;
out vec3 Normal;

uniform mat4 MVP;
uniform mat4 modelPosition;


// Offsets for our vertices drawing this face
const vec3 facePositions[4] = vec3[4]
(
	vec3(0.0f, 0.0f, 1.0f),
	vec3(1.0f, 0.0f, 0.0f),
	vec3(1.0f, 0.0f, 1.0f),
	vec3(0.0f, 0.0f, 0.0f)

  //vec3( 0.5f,  0.5f,  0.5f), // 10 up
  //vec3( 0.5f,  0.5f, -0.5f),
  //vec3(-0.5f,  0.5f, -0.5f),
  //vec3(-0.5f,  0.5f,  0.5f)

);

// Winding order to access the face positions
int indices[6] = {0, 1, 2, 1, 0, 3};

vec3 unpack(int idx) {
  const int i = idx / 6;
  const uint packedData = packedMeshData[idx];
  const int currVertexID = idx % 6;

  // Unpack the data we retrieved
  const uint x = (packedData) & uint(255);
  const uint y = (packedData >> 8) & uint(255);
  const uint z = (packedData >> 16) & uint(255);

  // Apply the offsets for our face so we can form the 2 triangles
  return vec3(x, y, z) + facePositions[indices[currVertexID]];
}

void main()
{
  // Create a custom index to access the mesh data in the right order
  vec3 position = unpack(gl_VertexID);

  // Output our position
  gl_Position = vec4(position, 1.0);
  FragmentPos = vec3(modelPosition * vec4(position,1));
  UV = vec2(0,0.5);

  //vec3 B = unpack(gl_VertexID + 1) - position;
  //vec3 C = unpack(gl_VertexID + 2) - position;
  //vec3 n = cross(C,B);
  //Normal = normalize(n);
  Normal = vec3(0,1,0);
}