Shader Series – Camera Motion Blur

Entry Number 2 in the MonoGame Shader Series I'm writing. This covers the implementation of camera motion blur in Metric Racer.

Motion blur is a key effect in racing games to convey speed and movement. This tutorial walks through the shader implementation and how to integrate it into your game engine.

Why Motion Blur?

Motion blur is essential in racing games because it:

• **Conveys Speed**: Creates a sense of velocity and fast-paced action
• **Reduces Aliasing**: Temporal filtering helps smooth jagged edges
• **Improves Immersion**: Makes the player feel the acceleration
• **Visual Polish**: Adds professional cinematic quality

Implementation Approach

The effect is achieved through:

1. Sampling the screen buffer multiple times

2. Slight offsets based on camera velocity

3. Weighted blending of samples

4. Performance optimization using downsample passes

Performance Considerations

• Use ping-pong rendertargets to avoid redundant reads
• Downsampling before blur significantly reduces bandwidth
• Cache velocity calculations to avoid redundant math
• Use lower resolution for motion vectors on slower hardware

The final result creates a dynamic streaking effect that makes Metric Racer feel faster and more dynamic when moving through the track.