#version 450
#extension GL_KHR_vulkan_glsl : enable

layout(location = 0) in vec3 aVertexPos;
layout(location = 1) in vec2 aUV;
layout(location = 2) in vec3 aNormal;
layout(location = 3) in vec3 aTangent;
layout(location = 4) in mat4 worldTransform;
layout(location = 8) in uvec2 integerData;

layout(location = 0) out struct
{
  vec4 vertPos; // location 0
  vec2 uv; // location = 1
  vec4 normal; // location = 2
  vec4 worldPos; // location = 3 
  vec3 worldNormal; // location = 4 

} Out;

struct GenericData
{
  //! Delta time
  float dt;

  //! Elapsed time of the application
  float elapsedTime;

  //! Viewport width of the scene (excluding imgui, that means smaller than window)
  uint viewportWidth;

  //! Ditto but for height
  uint viewportHeight;
};

// material stuff
layout(location = 5) out struct
{
  int materialIndex;
  uint eid;
  uint lightLayerIndex;
  vec3 screenSpacePos;


} Out2;

layout(set = 1, binding = 0) uniform CameraData
{
  vec4 position; 
  mat4 vpMat;
  mat4 viewMat;
  mat4 projMat;
} cameraData;

layout (set = 0, binding = 0) uniform GenericDataBuffer
{
  GenericData data;
} genericDataBuffer;

void main()
{
  Out2.materialIndex = gl_InstanceIndex;
  Out2.eid             = integerData[0];
  Out2.lightLayerIndex = integerData[1];

  // for transforming gBuffer position and normal data
  mat4 modelViewMat = cameraData.viewMat * worldTransform;

  // gBuffer position will be in view space
  Out.vertPos = modelViewMat * vec4(aVertexPos, 1.0f);

  Out.worldPos = worldTransform * vec4 (aVertexPos, 1.0f);

  // uvs for texturing in fragment shader
  Out.uv = aUV;

  mat3 mvTransInv = mat3 (transpose(inverse(modelViewMat)));
  mat3 modelTransInv = mat3 (transpose(inverse(worldTransform)));

  // normals are also in view space
  Out.normal.rgb = mvTransInv * aNormal.rgb;
  Out.normal.rgb = normalize (Out.normal.rgb);
  Out.worldNormal = normalize (modelTransInv * aNormal);

  // Get center of object in world position
  vec4 worldPos = vec4(worldTransform[3][0], worldTransform[3][1], worldTransform[3][2], 1.0f);
  
  // transform to clip space
  worldPos = cameraData.vpMat * worldPos;
  worldPos.xyz /= worldPos.w;
  
  // transform to screen space
  worldPos.xy = ((worldPos.xy + vec2(1.0f)) * vec2 (0.5f)) * vec2 (genericDataBuffer.data.viewportWidth, genericDataBuffer.data.viewportHeight);  

  Out2.screenSpacePos = worldPos.xyz;

  // clip space for rendering
  gl_Position = cameraData.vpMat * worldTransform * vec4 (aVertexPos, 1.0f);
}