mixin PerCameraData
{
	code
	{
		cbuffer PerCamera
		{
			float3	 gViewDir;
			float3 	 gViewOrigin;
			float4x4 gMatViewProj;
			float4x4 gMatView;
			float4x4 gMatProj;
			float4x4 gMatInvProj;
			float4x4 gMatInvViewProj;
			
			// Special inverse view-projection matrix that had projection entries that affect z and w eliminated.
			// Used to transform a vector(clip_x, clip_y, view_z, view_w), where clip_x/clip_y are in clip space, 
			// and view_z/view_w in view space, into world space				
			float4x4 gMatScreenToWorld;
			
			// Transforms a location in NDC, to the location of the same pixel on the previous frame. Used for
			// determining camera movement for temporal filtering
			float4x4 gNDCToPrevNDC;			
			
			// Converts device Z to world Z using this formula: worldZ = (1 / (deviceZ + y)) * x
			float2 	 gDeviceZToWorldZ;
			float2	 gNDCZToWorldZ;
			float2 	 gNDCZToDeviceZ;
			
			// x - near plane distance, y - far plane distance
			float2	 gNearFar;
			
			// xy - Viewport offset in pixels
			// zw - Viewport width & height in pixels
			int4 	 gViewportRectangle;
			
			// xy - (Viewport size in pixels / 2) / Target size in pixels
			// zw - (Viewport offset in pixels + (Viewport size in pixels / 2) + Optional pixel center offset) / Target size in pixels
			float4 	 gClipToUVScaleOffset;	
			float	gAmbientFactor;
		}
		
		/** Converts Z value in range [0,1] into Z value in view space. */
		float convertFromDeviceZ(float deviceZ)
		{
			// Note: Convert to MAD form
			return gDeviceZToWorldZ.x / (deviceZ + gDeviceZToWorldZ.y);
		}
		
		/** Converts Z value in range [0,1] into Z value in view space. */
		float4 convertFromDeviceZ(float4 deviceZ)
		{
			// Note: Convert to MAD form
			return gDeviceZToWorldZ.x / (deviceZ + gDeviceZToWorldZ.y);
		}		
		
		/** Converts Z value from view space to NDC space. */
		float convertToNDCZ(float viewZ)
		{
			return -gNDCZToWorldZ.y + (gNDCZToWorldZ.x / viewZ);
		}
				
		/** Converts Z value from NDC space to device Z value in range [0, 1]. */
		float NDCZToDeviceZ(float ndcZ)
		{
			return (ndcZ + gNDCZToDeviceZ.y) * gNDCZToDeviceZ.x;
		}
		
		/** Converts Z value from device range ([0, 1]) to NDC space. */
		float DeviceZToNDCZ(float deviceZ)
		{
			return deviceZ / gNDCZToDeviceZ.x - gNDCZToDeviceZ.y;
		}
		
		/** Converts position in NDC to UV coordinates mapped to the screen rectangle. */ 
		float2 NDCToUV(float2 ndcPos)
		{
			return ndcPos.xy * gClipToUVScaleOffset.xy + gClipToUVScaleOffset.zw;
		}
		
		/** Converts position in UV coordinates mapped to screen rectangle to NDC coordinates. */
		float2 UVToNDC(float2 uvPos)
		{
			return (uvPos - gClipToUVScaleOffset.zw) / gClipToUVScaleOffset.xy;
		}
		
		/** Converts position in UV coordinates mapped to the screen, to screen coordinates in pixels. */
		uint2 UVToScreen(float2 uv)
		{
			return (uint2)(uv * (float2)gViewportRectangle.zw - ((float2)gViewportRectangle.xy));
		}
		
		/** Converts position in NDC to screen coordinates in pixels. */
		uint2 NDCToScreen(float2 ndcPos)
		{
			float2 uv = NDCToUV(ndcPos);
			return UVToScreen(uv);
		}
		
		/** Converts position in NDC to world space. */
		float3 NDCToWorld(float2 ndcPos, float depth)
		{
			// x, y are now in clip space, z, w are in view space
			// We multiply them by a special inverse view-projection matrix, that had the projection entries that effect
			// z, w eliminated (since they are already in view space)
			// Note: Multiply by depth should be avoided if using ortographic projection
			float4 mixedSpacePos = float4(ndcPos.xy * -depth, depth, 1);
			float4 worldPosition4D = mul(gMatScreenToWorld, mixedSpacePos);
			
			return worldPosition4D.xyz / worldPosition4D.w;
		}
	};
};