Non-Photorealistic Rendering Techniques for a Game Engine
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Transcript of Non-Photorealistic Rendering Techniques for a Game Engine
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Non-Photorealistic Rendering Techniques for a Game Engine
COMP 238 Final Project
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Remember NPR Quake?
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
How did they do it?
• “grep”-ed the Quake source code for OpenGL calls
• Pulled them out into one source file
• Added dynamic loading support
• Started coding different visual styles
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
How about a “cartoon” look?• Silhouettes• Creases• Shading• Shadows• Walls
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Silhouettes
Flip the normals and extend the edges of backfacing polygons.
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Creases (1)
Add thin quadrilaterals at each edge, forming an angle with the polygon.
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Creases (2)
• It actually works!
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Shadows
• The function is there, but it’s never called :(.
• Just draw a projection of each model on a horizontal plane (not always correct, but works out pretty well).
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Cartoon-style shading
• 1D texture• coordinate at
vertex = amount of light received
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Walls
• No lighting information available, so…
• Replace with “hand-drawn” texture.
• Add charcoal style for lines (one thick line and several jittered thin lines).
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Result
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Bibliography
• [1] Alex Mohr, Michael Gleicher: "Non-Invasive, Interactive, Stylized Rendering". The 2001 ACM Symposium on Interactive 3D Graphics.
• [2] Ramesh Raskar: "Hardware Support for Non-photorealistic Rendering", Eurographics 2001.
• [3] Bert Freudenberg, Maic Masuch, Thomas Strothotte: "Walk-Through Illustrations: Frame-Coherent Pen-and-Ink Style in a Game Engine", Siggraph/Eurographics Graphics Hardware, LA, 2001.
• [4] Adam Lake, Carl Marshall, Mark Harris, Marc Blackstein: "Hardware Support for Non-photorealistic Rendering", Siggraph/Eurographics Graphics Hardware, LA, 2001.
• [5] Jeff Lander: "Shades of Disney: Opaquing a 3D World", Game Developer Magazine, March 2000.