1. SNOW ACCUMULATION AND
GENERATION
Yuanhui

2. MAIN PARTS
 Particle Rendering for Snow Generation
 Shadow Mapping for Snow Accumulation
 Fog Effect

3. SNOW ACCUMULATION
 Rendering Depth Map
 From the view of the sky with orthographic camera
 Render depth values to texture

4. SNOW ACCUMULATION
 Rendering Object
 Shadow testing: not exposed when depth larger than
depth map value
 Read depth map value
 VL = Ms * Mp * Mv * Mm * V
 VL projected vertex from light source
 Ms scale matrix (-1, 1) to (0, 1)
 Mp light source projection
 Mv light source view from world
 Mm model to world
 V vertices

5. SNOW ACCUMULATION
 Incline Coefficient
 dot(Y, normal)
http://http.download.nvidia.com/developer/SDK/Individual_Samples/
DEMOS/Direct3D9/src/SnowAccumulation/Docs/SnowAccumulation.pdf

6. SNOW GENERATION
 Random Position
 Particles Rendering
 glEnable(GL_POINT_SPRITE)
 glEnable(GL_VERTEX_PROGRAM_POINT_SIZE)
 gl_PointSize
 GL_POINTS
 Particle Animation
 calculate alpha (vertex shader)

7. FOG EFFECT
http://www.ozone3d.net/tutorials/glsl_fog/p02.php

8. REFERENCE
 http://http.download.nvidia.com/developer/SDK/Indi
vidual_Samples/DEMOS/Direct3D9/src/SnowAccu
mulation/Docs/SnowAccumulation.pdf
 https://graphics.stanford.edu/wikis/cs248-11-
winter/CS_248%3A_Interactive_Computer_Graphic
s?action=AttachFile&do=get&target=OpenGLParticl
es.pdf
 http://www.ozone3d.net/tutorials/glsl_fog
 http://www.opengl-tutorial.org/intermediate-
tutorials/tutorial-16-shadow-mapping/

9. THANKS!