Texture mapping for computer graphics display controller system

• US 5,097,427 A
• Filed: 03/26/1991
• Issued: 03/17/1992
• Est. Priority Date: 07/06/1988
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Voorhies, Douglas A., Lathrop, Olin G., Kirk, David B.
• Primary Examiner(s): Herndon, Heather R.
• Application Number:
  US07/679,152
• Time in Patent Office: 357 Days
• Field of Search: 364/518, 364/521, 364/522, 340/703, 340/721, 340/747, 340/750, 340/701, 340/707
• US Class Current: 345/587
• CPC Class Codes: G06T 15/50 Lighting effects

Abstract

Texture mapping apparatus includes a memory for storing input texture values, interpolators for generating illumination values for sets of display pixels, elements for addressing the memory to generate output texture values, and logic elements for combining the output texture values and the illumination values to generate display color values for each pixel.

Claims

1. In a computer graphics display controller system for processing first electrical signals to generate electrical display signals to display an image of an object on an electrical display element, the image being defined by electrical display signals corresponding to selected display pixels of the image, the improvement comprising

texture mapping apparatus comprising

A. illumination signal generating means, including electrical logic elements, responsive to selected addresses corresponding to selected display pixels, for generating electrical illumination signals representative of illumination values corresponding to respective ones of said display pixel addresses,

B. texture index signal generating means, including electrical logic elements, responsive to said selected pixel addresses, for generating an electrical texture index signal representative of a texture index value for each said selected pixel address, each said texture index value being associated with a respective texture value for each said selected pixel address, said electrical texture signals being storable in an electrical storage element including a texture table addressable by said texture index signals,

said texture index signal generating means including texture index signal interpolation elements for interpolating initial texture index signals to generate further texture index signals, said initial texture index signals corresponding to initial pixel addresses and said further texture index signals corresponding to further pixel addresses,

C. electrical combining means, including combinatorial logic elements, in electrical communication with said illumination signal means and said texture index signal generating means, responsive to said illumination signals and said texture signals, for electrically combining respective ones of said illumination signals and said texture signals to generate electrical display signals corresponding to said selected pixels, for application to the display element to display the image, and

D. electrical output means, in electrical communication with said electrical combining means, and electrically connectable to the display device, for transmitting said electrical display signals to the display device to display said image representative of an object.

2. Apparatus according to claim 1, wherein said illumination value means includes illumination value interpolation means for interpolating initial illumination values to generate further illumination values.

3. Apparatus according to claim 2, wherein said polynomial logic means includes means for calculating polynomials of less than or equal to order two.

4. Apparatus according to claim 3, wherein said polynomial logic means includes incremental evaluation means for executing incremental evaluation of said polynomials.

5. Apparatus according to claim 4, wherein said incremental evaluation means includes forward differencing means for evaluating said selected polynomials.

6. Apparatus according to claim 3, wherein said polynomial logic means includes non-incremental evaluation means for executing non-incremental evaluation of said selected polynomials.

7. Apparatus according to claim 6, wherein said non-incremental evaluation means includes means for executing direct evaluation of said selected polynomials.

8. Apparatus according to claim 6, wherein said non-incremental evaluation means includes means for executing spline functions utilizing values of selected control points.

9. Apparatus according to claim 1, wherein said illumination value means and said polynomial logic means collectively include at least one interpolator means for (i) interpolating said illumination values during selected operational periods and (ii) interpolating said texture index values during other operational periods.

10. In a computer graphics display controller system for processing first electrical signals to generate electrical display signals to display an image of an object on a display element, the image being defined by electrical display signals corresponding to selected display pixels of the image, the improvement comprising

texture mapping apparatus comprising

A. illumination signal generating means, including electrical logic elements, responsive to selected addresses corresponding to selected display pixels, for generating electrical illumination signals representative of illumination values corresponding to respective ones of said display pixel addresses,

B. texture table means including an electrical storage element for storing texture signals representative of texture values, said texture table means being addressable by electrical texture index signals, said texture index signals being representative of values of polynomial functions of said selected pixel addresses, said texture table means further including

interpolation means, including electrical interpolator elements, for interpolating first texture index signals representative of initial values of said polynomial functions to generate further texture index signals representative of further values of said polynomial functions, said initial values of said polynomial functions corresponding to initial display pixel addresses and said further values of said polynomial functions corresponding to further display pixel addresses, and

electrical mip-map storage means for retrievably storing indexed, differently scaled mappings of said testures signals, said differently scaled mappings being selected by at least one of said signals representative of interpolated values of said polynomial functions,

C. electrical combining means, including combinatorial logic elements, in electrical communication with said illumination signal means and said texture table means, for electrically combining respective ones of said illumination signals and said texture signals associated with a selected one of said differently scaled mappings to generate display signals corresponding to said selected pixels, for application to the display element to display the image, and

D. output means, in electrical communication with said electrical combining means, and electrically connectable to the display device, for transmitting said electrical display signals to the display device to display said image representative of an object.

11. In a computer graphics display controller system for processing first electrical signals to generate digital electrical display signals to display an image of an object on a display element, the image being defined by electrical display signals corresponding to selected display pixels of the image, the improvement comprising

texture mapping apparatus comprising

A. illumination signal generating means, including logic elements, responsive to selected addresses corresponding to selected display pixels, for generating electrical illumination signals representative of illumination values corresponding to respective ones of said display pixel addresses,

B. texture table means, including an electrical storage element for storing texture signals, said texture table storage means being addressable by electrical texture index signals having values representative of polynomial functions of said selected pixel addresses, said texture table means including

electrical mip-map storage means for retrievably storing indexed, differently scaled mappings of said texture signals, said differently scaled mapping being selected by at least one of said texture index signals,

C. electrical combining means, including combinatorial logic elements, in electrical communication with said illumination signal means and said texture table means, for electrically combining respective ones of said illumination signals and said texture signals associated with a selected one of said differently scaled mappings to generate display signals corresponding to said selected pixels, for application to the display element to display the image,

D. partial derivative means, including electrical logic elements, in electrical communication with said texture table means, for generating electrical signals representative of partial derivatives of said at least one texture index signal with respect to said selected pixel addresses, and

F. scaling means, including electrical logic elements, in electrical communication with said partial derivative means and said texture table means, for selecting, responsive to said signals representative of partial derivatives, one of said mappings of said texture values for transmitting texture values to said combining means, and

G. output means, in electrical communication with said electrical combining means, and electrically connectable to the display device, for transmitting said electrical display signals to the display device to display said image representative of an object.

12. Apparatus according to claim 11, wherein said texture table means includes limiting means for selectively limiting the range of differently scaled mappings selectable by values of at least one said partial derivative.