A simple programmable soft rendering toy constructed based on Direct3D concepts. It can be used as a demonstration of how 3D graphics devices work.

Warning: some features are still to be fixed.

Direct3D uses a graphics pipeline to process graphics. The stages is visualized as the graph below:

In this project, these "blocks" are implemented:

• Memory Resources
• Input Assembler
• Vertex Shader
• Rasterizer
• Pixel Shader
• Output Merger (depth test and blending)

Due to a clear design, the rest of the "blocks" can also be inserted if you want to.

This project's code base is much larger than tinyrenderer, because this project implemented some advanced features:

• More realistic pipeline. Every stage is separated from the others. The shaders you write behave the same as real shaders. So in a shader, you cannot access anything outside the shader. And for the graphics device, it requires only a few things (see IVertexShaderInput and IPixelShaderInput), exactly matching Direct3D's requirements.
• Culling and clipping.
  • Back face culling: Drops triangles according to their orientation (clockwise, counterclockwise). It is used to speed up the performance.
  • Clipping (TBF): Znear and Zfar / X-Y
• Blending. Proper blending is necessary for correctly rendering overlapped pixels with transparency.

The rendering pipeline in OpenGL is similar to that in Direct3D. But there is a major difference in coordinate systems. In Direct3D, the transformed vertex coordinates (X, Y, Z) in the CVV range from -1 to 1, and, traditionally, the input should use a left-hand coordinate system. OpenGL, on the other hand, requires the coordinate values ranging from 0 to 1, and uses a right-hand coordinate system.

The Unlicense