3D Rendering Pipeline

Each of these stages are pipelines in themselves. The slowest stage determine the rendering speed.

Application

• Driven by the software and so is implemented in software.
• May contain: collision detections, animations, keyboard input, morphing, etc.
• At the end of this stage, the geometry to be rendered is fed to the next stage.

Geometry

• Implemented in software or hardware depending on architecture.
• Responsible for the majority of per-polygon and per-vertex operations.
• Deals with: projections, transforms, lighting, etc.
• Computes what is to be drawn, how things are to be drawn, and where things are to be drawn.

Rasterizer

• Assigns correct colors to the pixels, a process referred to as rasterization or scan conversion.
• Information for each pixel is stored in a color buffer.
• For high permformance, this stage must be implemented in hardware.
• Double buffering is generally used using a front and back buffer.
• A Z-buffer (or depth buffer) is used to determine visibility.
• Other buffers may be used to affect the color: alpha channel stores opacity values, stencil buffer, etc
• A frame buffer may refer to all the buffers together or may just refer to the color and z-buffer together.
• More recently, an accumulation buffer is used to average images such as for anti-aliasing, or for creating motion blur.