WILLIAM MOSS ADVANCED RENDERING COURSE PROJECT DECEMBER 4 TH, 2008 Real-time rendering of water and bubbles

Desired Effects Water  Local reflections  Refraction  External Lighting  Fresnel Effect Bubbles  Refraction  External Lighting (specular highlight)

Water Effects

Local Reflection Model water surface as a mirror  Reflect the scene over the rest water height  Clip  Render to a texture

Refraction Model water surface as a plane  Clip everything below water surface  Scale along vertical direction by 1 / 1.33  Render to a texture

Texture to Surface Find screen position of undisplaced water surface position  Offset by the normal scaled by surface displacement  Lookup in the texture  tex2D(textureMap, screenPos.xy – displacement * normal.xz);

External Lighting Simple Phong model for specular highlights  Assume light is coming from infinitely far away (as in the sun)

Fresnel Effect Probability a photon is reflected or transmitted  Dependent on the incident angle  Formula is expensive, implemented as a 1D texture lookup

Bubble Effects

Refraction Model bubble as one sided hemisphere  Refract the ray from the eye  Calculate the intersection with the ground plane  Lookup in a texture

External Lighting Simple Phong model for specular highlights  Assume light is coming from infinitely far away (as in the sun)

Results Runs at ~30-40fps on my laptop Shaders written in NVidia Cg