WILLIAM MOSS

A DVA N C E D R EN D E R I N G C O U R S E P R O J E C TD EC E M B E R 4 T H , 2 0 0 8

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 laptopShaders written in NVidia Cg