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Shadows
GPU Shadow Volume Construction for Nonclosed Meshes |  |
Abstract: This article presents a method of rendering shadow volumes without requiring a two-manifold, closed mesh.
Perspective Shadow Maps | |
Abstract: Perspective shadow maps are very similar to standard shadow maps, but are distorted such that regions close to the camera have higher resolution than distant regions. This article describes the details of perspective shadow maps, demonstrates how they are generated, and discusses how typical pitfalls can be avoided.
Combined Depth and ID-Based Shadow Buffers | |
Abstract: This article describes a hybrid approach that combines the techniques of both depth and ID-based shadow buffers, exploiting the advantages of both methods. This approach allows for self-shadowing and supports up to 42,875 unique IDs.
Carving Static Shadows into Geometry
Abstract: This article describes a method of carving hard shadows directly into static geometry to create crisp, hard scene shadows that are consistent with the look of the stencil shadows typically used for characters. After the carving process, each resulting polygon is marked as either "in light" or "in shadow" for later rendering. This saves the overhead of rendering full shadow volumes for every detail in a scene, resulting in significant fill-rate savings. Additionally, we will briefly discuss how to dynamically cast shadows on moving objects using low-resolution proxy shadow volumes.
Adjusting Real-Time Lighting for Shadow Volumes and Optimized Meshes
Abstract: Lighting an entire mesh is well understood and presents no real, unexpected artifacts. However, when more complex rendering systems optimize the number of polygons being rendered, like backface-culling from the light's point of view, lighting artifacts are introduced. When culling is done based on face normals and lighting is done based on vertex normals, some adjustments are required. The same applies to self-shadowing meshes that use stencil shadow volumes, since the shadow volumes are extruded based on face normals. Additionally, bump mapping needs even further adjustment, because the normal has nothing to do with the geometric shape of the mesh. This article explores these problems and presents a solution that is accomplished entirely in the pixel shader.
Practical Shadows: Out of the Demo and Into the Engine
Abstract: There are many shadowing algorithms available, such as blob shadows, shadow maps of various types, projective shadow maps, and stencil volume shadows. But they all have limitations, some of them work on some platforms and not others, each is appropriate for different situations. This lecture introduces each method and briefly discusses their major features and limitations. It then explores how to mix and match the various methods in a practical large-world engine on real console hardware. The lecture is mainly about the tricks and tips, where corners can be cut, when to use each technique, and the efficiency and scalability of each. The emphasis is using these methods in a practical game with large, complex and unconstrained scenes, rather than simply writing a technology demo.
Computing Optimized Shadow Volumes for Complex Data Sets
Abstract: In this article, we describe a method for computing the exact front cap geometry visible from a given static light source. This is the exact geometry that is visible from the light's point of view, and it is useful for calculating shadow volumes. Previous work has been done on this topic; however, most methods suffer from either infinte recursion (with complex polygonal models) or fail to solve for cyclically overlapping polygons. The method presented here also works for scenes that have intersecting polygons.
A Modified Phong-Blinn Light Model for Shadowed Areas  |  |
Tony Barrera (Barrera Kristiansen AB), Anders Hast (Creative Media Lab, University of Gävle), and Ewert Bengtsson (Center for Image Analysis, Uppsala University)
Graphics Programming Methods, 2003. |
Abstract:
True Volumetric Shadows | |
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The Mechanics of Robust Stencil Shadows
Abstract: This article presents the intricacies of the entire stencil shadow algorithm and covers every mathematical detail of its efficient implementation.
Self-Shadowing Characters
Abstract: This article presents a projective texture approachk, which enables self-shadowing of convex subsections of characters in real time. After breaking the character into convex subsections, the subsections are rendered into a texture with varying alpha values from teh point of view of the light source. When the character is rendered from the viewer's point-of-view, this texture is projected back onto the convex subsegments of the character, simulating the occlusion of each subsegment with respect to the light source. Being map based rather than stencil-volume based, this technique requires no additional work to be compatible with higher-order surface tessellation techniques.
Practical Priority Buffer Shadows
Abstract: This article presents a set of techniques to improve the utility of "priority buffers". Along the way, we will explore other shadow techniques, and close by discussing how to create useful hybrid techniques.
Ground-Plane Shadows | |
Abstract:
Real-Time Shadows on Complex Objects | |
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Inside Direct3D: Stencil Buffers
Abstract: Many 3D games and simulations on the market use cinema-quality special effects to add to their dramatic impact. Stencil buffers can create effects such as composites, decals, dissolves, fades, outlines, silhouettes, swipes, and shadows. Stencil buffers determine whether the pixels in an image are drawn. This means your software can "mask" portions of the rendered image so that they aren't displayed.
Real-Time Shadow Casting Using Shadow Volumes
Abstract: Despite the rich colors, intricate textures, and dazzling effects in today's games, the human brain still notices that something is missing, and that something might just be shadows. Running with this idea, Jason Bestimt and Bryant Freitag discuss real-time dynamic shadowing using shadow volumes, presenting techniques and code listings for creating accurate shadows in 3D environments.
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