This document discusses techniques for rendering realistic rain effects in real-time city environments. It describes generating multiple rain layers, rendering raindrops and splashes, simulating dynamic water puddles, and depicting effects of rain on surfaces like glass including moving droplets, foggy lights, and windshield wipers. The goal is to create an immersive experience of driving in the rain within a virtual city.

1. Artist-Directable Real-Time
Rain Rendering in City
Environments (2/2)

4. 3.5.1 View-dependent streaky
reflection rendering

5. 3.5.2 Dynamic reflections for a
reflective taxi

6. 3.6 Rendering rain
• Rainfall consists of specially distributed
water drops falling at high velocity.
• As the raindrops fall through the
environment, they create the perception
of motion blur and generate ripples and
splashes in the puddles.

7. 3.6.1 Rendering multiple layers
of rain with a post-processing
composite effect

8. • Multiple layers of rain
• Rain appearance
• Raindrop transparency
• Compositing rain via blending

9. 3.6.2 Raindrop Particles Rain

10. 3.6.3 Rendering raindrop
splashes(1/2)

11. 3.6.3 Rendering raindrop
splashes (2/2)

12. 3.7 GPU-Based water simulation
for dynamic puddle rendering

14. Water puddles integration

15. Puddle Placement and Depth

16. Creating Swirling Water Puddle

17. 3.8 Raindrop movement and
rendering on glass surfaces in
real time

18. Droplet movement/
Droplet rendering

19. 3.8.1 Foggy lights in the street

20. 3.8.3 Traffic light illumination

21. 3.8.4 Rendering Misty Rain
Halos on Objects

22. 3.8.5 Taxi windshield wipers
effect for wiping off the
droplets

23. CONCLUSIONS