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Accelerated Stereoscopic Rendering using GPU. WSCG'2008. François de Sorbier - Université Paris-Est France February 2008. Problematic. Two-pass rendering Computational time doubled. Introduction. 2. Hypothesis. Shared attributes on vertices Colour Geometry etc
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Accelerated Stereoscopic Renderingusing GPU WSCG'2008 François de Sorbier - Université Paris-Est France February 2008
WSCG'2008 - February 2008 Problematic • Two-pass rendering • Computational time doubled Introduction 2
WSCG'2008 - February 2008 Hypothesis • Shared attributes on vertices • Colour • Geometry • etc • Use graphical processor • Duplicate the geometry • Transformations according to the viewpoint • Geometry Shaders Introduction 3
WSCG'2008 - February 2008 Outline • Geometry shaders • Our algorithm • Results • Conclusions 4
WSCG'2008 - February 2008 Geometry Shader VERTEX SHADER GEOMETRY SHADER RASTERIZATION FRAGMENT SHADER FRAMEBUFFER Geometry shaders 5
WSCG'2008 - February 2008 Example Input primitive Output primitives Geometry shaders 6
WSCG'2008 - February 2008 Geometry Shader Our method overview View 1 View 2 Our Algorithm 7
WSCG'2008 - February 2008 Images generation • Fragment shaders processing • Fragment's origin • Rendering buffer selection (Multiple Render Targets) • Standard operations • Rendering into two textures • Using FrameBuffer Object • MRT + FBO involve constraints Our Algorithm 8
WSCG'2008 - February 2008 Constraints • No separated depth buffer • Use painter algorithm on objects • Back Face Culling • Have to render a fragment into the two buffers • Colour and alpha set to 0 • Mix function for blending Our Algorithm 9
WSCG'2008 - February 2008 Our Algorithm 10
WSCG'2008 - February 2008 Improvement hypothesis ? Our Algorithm 11
WSCG'2008 - February 2008 Algorithm • Get depth map • Transmit vertices' position with duplicated geometry (GS) • Apply our own depth test (FS) • Get correct position in the depth map • Comparison with current fragment depth Our Algorithm 12
WSCG'2008 - February 2008 Our Algorithm 13
WSCG'2008 - February 2008 Results • nVidia GeForce 8800 GTX • 80.000 triangles Results 14
WSCG'2008 - February 2008 Conclusions • Limitations • “home made” depth test • Advantages • Only one rendering pass • Reduces computational time • First release of geometry shader Conclusion 15
WSCG'2008 - February 2008 Extensions • Depth test enhancement • Separated depth buffers? • Algorithm? • Autostereoscopic screens • Up to 8 views (first results) Conclusion 16
Thank you! francois.desorbier@univ-paris-est.fr WSCG'2008 - February 2008 17