Graphics pipeline for rendering graphics
A graphics pipeline ( 20 ) for rendering graphics receives texture data ( 22 ) and vertex data ( 23 ). The texture data ( 22 ) define rectangular texture maps ( 24 ), which are axis-aligned in texture space. The vertex data ( 23 ) describe output quadrilaterals ( 25 ) in screen space. A rasterizer ( 27 ) rasterizes the input rectangle ( 24 ) by determining which texels are inside the input rectangle ( 24 ). A mapper ( 28 ) maps the texels inside the input rectangle ( 24 ) onto the output quadrilaterals ( 25 ). The mapping is performed by calculating screen space output coordinates from the texture space grid coordinates of the texels. For the calculation an equation is used comprising at least one linear combination of the texture space grid coordinates of the texels inside the input rectangles ( 24 ) and at least one product of real powers of the texture space grid coordinates of the texels inside the input rectangles ( 24 ).
1. A graphics pipeline for rendering graphics using forward texture mapping, the pipeline comprising:
an input for receiving texture data and vertex data, the texture data defining texture maps in a texture space, each texture map comprising texels associated with texture space grid coordinates (u g ,v g ), the vertex data comprising texture space input coordinates (u r ,v r ) of input rectangles and screen space input coordinates (x h r ,y h r ,w h r ) of output quadrilaterals, the input rectangles being axis-aligned in the texture space, each one of the input rectangles being associated with a corresponding one of the output quadrilaterals;
a rasterizer for receiving the texture space input coordinates of the input rectangles and for providing the texture space grid coordinates of the texels inside the input rectangles; and
a mapper for mapping the texels inside the input rectangles onto the output quadrilaterals, the mapping being performed by calculating screen space output coordinates (x c ,y c ) from the texture space grid coordinates of the texels and the screen space input coordinates of the output quadrilaterals using a mapping function comprising at least one linear combination of the texture space grid coordinates of the texels inside the input rectangles, and at least one product of real powers (u g n v g m n,mεR) of the texture space grid coordinates of the texels inside the input rectangles;
wherein the graphics pipeline renders graphics using forward texture mapping.
2. A graphics pipeline as claimed in claim 1 , wherein the real powers are natural powers.
3. A graphics pipeline as claimed in claim 2 , wherein the natural powers are equal to one.
4. A graphics pipeline as claimed in claim 1 , further comprising a screen space resampler for splatting a color of each one of the texels onto pixel positions surrounding the screen space output coordinates which are calculated from the texture space grid coordinates of the corresponding one of the texels.
5. A method for rendering graphics using forward texture mapping to be displayed on a display, the method comprising:
receiving, using an input, texture data and vertex data, the texture data defining texture maps in a texture space, each texture map comprising texels associated with texture space grid coordinates (u g ,v g ), the vertex data comprising texture space input coordinates (u r ,y r ) of input rectangles and screen space input coordinates (x h r ,y h r ,w h r ) of output quadrilaterals, the input rectangles being axis-aligned in the texture space, each one of the input rectangles being associated with a corresponding one of the output quadrilaterals;
providing, using a rasterizer, the texture space grid coordinates of the texels inside the input rectangles from the texture space input coordinates of the input rectangles; and
mapping, using a mapper, the texels inside the input rectangles onto the output quadrilaterals, the mapping being performed by calculating screen space output coordinates (x c ,y c ) from the texture space grid coordinates of the texels and the screen space input coordinates of the output quadrilaterals using a mapping function comprising at least one linear combination of the texture space grid coordinates of the texels inside the input rectangles, and at least one product of real powers (u g n v g m n,mεR) of the texture space grid coordinates of the texels inside the input rectangles;
wherein the graphics are rendered using forward texture mapping.
6. A computer comprising a graphics pipeline as claimed in claim 1 .
7. A device for displaying graphics, the device comprising:
a graphics pipeline as claimed in claim 1 , and
a display for displaying the graphics rendered by the pipeline.
8. The graphics pipeline as claimed in claim 1 wherein the screen space input coordinates (x h r ,y h r ,w h r ) is a product of a mapping coefficient matrix and a column vector.
9. The graphics pipeline as claimed in claim 8 wherein the mapping coefficients are determined as a function of texture space input coordinates of an input rectangle, and screen space output coordinates of an output quadrilateral.
10. The graphics pipeline as claimed in claim 8 wherein the column vector comprises the texture space grid coordinates of the texels inside the input matrix, a product of real powers of the texture space grid coordinates of the texels inside the input matrix, and a constant element.
11. The graphics pipeline as claimed in claim 2 wherein the screen space input coordinates (x h r ,y h r ,w h r ) is a product of a mapping coefficient matrix and a column vector.
12. The graphics pipeline as claimed in claim 11 wherein the mapping coefficients are determined as a function of texture space input coordinates of an input rectangle, and screen space output coordinates of an output quadrilateral.
13. The graphics pipeline as claimed in claim 11 wherein the column vector comprises the texture space grid coordinates of the texels inside the input matrix, a product of real powers of the texture space grid coordinates of the texels inside the input matrix, and a constant element.
14. The graphics pipeline as claimed in claim 3 wherein the screen space input coordinates (x h r ,y h r ,w h r ) is a product of a mapping coefficient matrix and a column vector.
15. The graphics pipeline as claimed in claim 14 wherein the mapping coefficients are determined as a function of texture space input coordinates of an input rectangle, and screen space output coordinates of an output quadrilateral.
16. The graphics pipeline as claimed in claim 14 wherein the column vector comprises the texture space grid coordinates of the texels inside the input matrix, a product of real powers of the texture space grid coordinates of the texels inside the input matrix, and a constant element.
17. The graphics pipeline as claimed in claim 4 wherein the screen space input coordinates (x h r ,y h r ,w h r ) is a product of a mapping coefficient matrix and a column vector.
18. The graphics pipeline as claimed in claim 17 wherein the column vector comprises the texture space grid coordinates of the texels inside the input matrix, a product of real powers of the texture space grid coordinates of the texels inside the input matrix, and a constant element.
19. The method of claim 5 wherein the screen space input coordinates (x h r ,y h r ,w h r ) is a product of a mapping coefficient matrix and a column vector.
20. The method of claim 19 wherein the column vector comprises the texture space grid coordinates of the texels inside the input matrix, a product of real powers of the texture space grid coordinates of the texels inside the input matrix, and a constant element.