Function FormatTexture

Chapter_14/src/Textures.cpp:80–140

* Compute the aligned memory required for the texture. * Add texels to the texture if either dimension is not a factor of 4 (required for BC7 compressed formats). */

	 * Add texels to the texture if either dimension is not a factor of 4 (required for BC7 compressed formats).
	 */
	bool FormatTexture(TextureData& texture, DirectX::XMFLOAT2& uvAdjustment)
	{
		// BC7 compressed textures require 4x4 texel blocks
		// Add texels to the texture if its original dimensions aren't factors of 4
		if (texture.width % 4 != 0 || texture.height % 4 != 0)
		{
			// Get original row stride
			UINT originalWidth = texture.width;
			UINT rowSize = (texture.width * texture.stride);
			UINT numRows = texture.height;

			// Align the new texture to 4x4
			texture.width = ALIGN(4, texture.width);
			texture.height = ALIGN(4, texture.height);

			UINT alignedRowSize = (texture.width * texture.stride);
			UINT size = alignedRowSize * texture.height;

			// Figure out uv adjustment needed due to padding (we want UVs to point to the area where original unpadded texture is)
			uvAdjustment.x = float(originalWidth) / float(texture.width);
			uvAdjustment.y = float(numRows) / float(texture.height);

			// Copy the original texture into the new one
			size_t offset = 0;
			size_t alignedOffset = 0;
			UINT8* texels = new UINT8[size];

			for (UINT row = 0; row < numRows; row++)
			{
				memcpy(&texels[alignedOffset], &texture.texels[offset], rowSize);
				
				// Fill empty space in the aligned row with border pixel value
				for (UINT i = 0; i < texture.width - originalWidth; i++) {
					memcpy(&texels[alignedOffset + rowSize + (i * UINT(texture.stride))], &texels[alignedOffset + rowSize - texture.stride], texture.stride);
				}

				alignedOffset += alignedRowSize;
				offset += rowSize;
			}
			
			// Copy last row values into new rows
			UINT lastRowOffset = alignedOffset - alignedRowSize;
			for (UINT row = 0; row < texture.height - numRows; row++)
			{
				memcpy(&texels[alignedOffset], &texels[lastRowOffset], alignedRowSize);

				alignedOffset += alignedRowSize;
				offset += rowSize;
			}

			// Release the memory of the original texture
			UnloadTextureData(texture);
			texture.texels = texels;
		}

		// Compute the texture's aligned memory size
		texture.rowPitch = (texture.width * texture.stride);
		texture.texelBytes = (texture.rowPitch * UINT64(texture.height));