Method for rendering shadows on a graphical display
First Claim
1. A method for rendering a shadow in a computer graphics display system which generates three-dimensional information that is expressive of three-dimensional solid objects therein which cast and receive the shadow, wherein the method comprises the steps of:
- (a) generating a three-dimensional shadow casting object having a shape attribute defining a corresponding shape and a three-dimensional shadow receiving object having at least one appearance attribute defining a corresponding appearance;
(b) generating a light source so that the shadow casting object is at least partially illuminated and oriented so as to cast the shadow at least partially onto the shadow receiving object, to thereby generate a shadow polygon also having a shape attribute and corresponding shape derived from the shadow casting object;
(c) combining the shape attribute of the shadow region and the at least one appearance attribute of the shadow receiving object to enable the shadow polygon to have an appearance of the shadow receiving object; and
(d) utilizing shading algorithms to render the shadow region.
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Accused Products
Abstract
A method for rendering a shadow cast from an object illuminated by at least one light source onto at least another object on a graphical computer display. The preferred embodiment enables the rendering of accurate and realistic shadows in real-time, consequently providing a realistic view of three-dimensional objects in two dimensions. The shadow can also provide more visual clues than are otherwise available from ambient light sources. In this way, more visual information is provided to an observer.
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Citations
32 Claims
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1. A method for rendering a shadow in a computer graphics display system which generates three-dimensional information that is expressive of three-dimensional solid objects therein which cast and receive the shadow, wherein the method comprises the steps of:
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(a) generating a three-dimensional shadow casting object having a shape attribute defining a corresponding shape and a three-dimensional shadow receiving object having at least one appearance attribute defining a corresponding appearance; (b) generating a light source so that the shadow casting object is at least partially illuminated and oriented so as to cast the shadow at least partially onto the shadow receiving object, to thereby generate a shadow polygon also having a shape attribute and corresponding shape derived from the shadow casting object; (c) combining the shape attribute of the shadow region and the at least one appearance attribute of the shadow receiving object to enable the shadow polygon to have an appearance of the shadow receiving object; and (d) utilizing shading algorithms to render the shadow region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A method for rendering a shadow in a computer graphics display system which generates three-dimensional information that is expressive of three-dimensional solid objects therein which cast and receive the shadow, wherein the method comprises the steps of:
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(a) generating a three-dimensional shadow casting object optionally having a texture map and a three-dimensional shadow receiving object optionally having a texture map; (b) generating a light source so that the shadow casting object is at least partially illuminated and oriented so as to cast the shadow at least partially over the shadow receiving object; (c) disabling light source illumination calculations where the shadow is cast over the shadow receiving object to thereby generate a shadow region; and (d) utilizing shading algorithms to render the shadow region.
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31. A method for rendering a shadow in a computer graphics display system which generates three-dimensional information that is expressive of three-dimensional solid objects therein which cast and receive the shadow, wherein the method comprises the steps of:
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(a) generating a three-dimensional shadow casting object having a texture map and a three-dimensional shadow receiving object having a texture map; (b) generating a light source so that the shadow casting object is at least partially illuminated and oriented so as to cast the shadow at least partially over the shadow receiving object to thereby generate a shadow polygon; (c) generating a shadow shape from a copy of the shadow casting object texture map; (d) coupling the shadow shape to vertices of the shadow polygon; (e) causing the shadow shape to inherit all colors of the shadow receiving object; (f) applying the shadow casting object texture map as a composite mask over shadow receiving object to complete the shadow; and (g) utilizing shading hardware to render the shadow.
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32. A computer graphics system for rendering a shadow on a computer graphics display system which generates three-dimensional information that is expressive of three-dimensional solid objects therein which cast and receive the shadow, wherein the system is comprised of:
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a display means for displaying a three-dimensional shadow casting object, a three-dimensional shadow receiving object, a light source and a shadow extending from the shadow casting object so as to at least partially obscure the shadow receiving object; a processing means for calculating attributes of the shadow casting object, the shadow receiving object, the light source and the shadow, where the processing means includes separate illumination calculating means for determining how the light source illuminates the shadow casting object and the shadow receiving object; and shadow rendering means for rendering the shadow after the processing means has determined the shape of the shadow.
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Specification