non-photorealistic rendering techniques for a game engine
DESCRIPTION
COMP 238 Final Project. Non-Photorealistic Rendering Techniques for a Game Engine. Remember NPR Quake?. 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. - PowerPoint PPT PresentationTRANSCRIPT
The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Non-Photorealistic Rendering Techniques for a Game Engine
COMP 238 Final Project
The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Remember NPR Quake?
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
The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
How about a “cartoon” look?• Silhouettes• Creases• Shading• Shadows• Walls
The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Silhouettes
Flip the normals and extend the edges of backfacing polygons.
The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Creases (1)
Add thin quadrilaterals at each edge, forming an angle with the polygon.
The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Creases (2)
• It actually works!
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).
The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Cartoon-style shading
• 1D texture• coordinate at
vertex = amount of light received
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).
The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL
Adrian Ilie
Result
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.