Parallax Voxel Ray Marcher

Project in High Performance Computer Graphics (3rd place) at LTH by Theodor Lundqvist, Jiuming Zeng and Jintao Yu.

Video: https://youtu.be/21KFuvCqHIU (10000+ views)

Paper: Parallax Voxel Ray Marcher.pdf

                         

Some personal notes:

Grid Traversal

• FVTA Algorithm: Efficient voxel traversal algorithm for ray casting through a grid.
  Paper (Amanatides & Woo)

Mesh to Voxel Conversion

• Convert mesh models into voxel grids:
  • David Stutz's mesh voxelizer (GitHub)
  • Drububu online voxelizer (OBJ export)

Voxel Ray Marching

• Teardown-style voxel rendering:
  • YouTube: How Teardown Does Destruction
• Parallax voxel raymarching:
  • YouTube
• Distance fields:
  • Fast on GPU but can still be slower than grid-based methods
  • YouTube: Distance Fields Explained

Atomontage Engine

• Highly optimized voxel engine supporting dynamic updates and intersections:
  • Overview
  • Rendering approach
  • Advanced techniques

Fragment Shader Techniques

• Depth Handling in Voxel Rendering:
  • Early depth test must be disabled when depth is modified in the fragment shader.
  • Use the conservative_depth extension:
    • OpenGL: Conservative Depth
    • Shader declaration example:

      layout (depth_less) out float gl_FragDepth;

    • This declares that fragments will always move closer than their original depth (e.g. when rendering backfaces).

Cool Shader Examples

• Impressive real-time voxel rendering:
  • Shadertoy: Voxel Cone Tracing
  • Shadertoy: Soft Voxel Global Illumination
  • Shadertoy: Sparse Voxel Rendering