Computer graphics system and method for texture mapping using triangular interpolation

A method for texture mapping in a computer graphics system, comprising the steps of:

• (1) mapping a pixel from an image space to a sample point in a texture space;
• (2) identifying three texels in said texture space forming a triangular region enclosing said sample point;
• and
• (3) calculating a texture related value of said pixel mapped to said sample point in said texture space by triangular interpolating on corresponding texture related values of said three texels.

A computer graphics method, comprising the steps of:

• (1) mapping a pixel from an image space to a sample point in a texture space, said sample point having coordinates (si+sf, ti+tf);
• (2) identifying three texels in said texture space forming a triangular region enclosing said sample point;
• (3) determining whether said triangular region represents a lower region or an upper region;
• (4) if said triangular region represents a lower region, then calculating a texture related value of said pixel mapped to said sample point by triangular interpolating on corresponding texture related values of said three texels according to a first equation:
• texture related value=texel›s,t!+(texel›s+1,t!-texel›s,t!) * sf+(texel›s,t+1!-texel›s,t!) * tf;
• (5) if said triangular region represents an upper region, then calculating a texture related value of said pixel mapped to said sample point by triangular interpolating on corresponding texture related values of said three texels according to a second equation:
• ##EQU9## (6) storing said texture related value calculated in step (4) or step (5) in a frame buffer;
• and
• (7) transferring said texture related value from said frame buffer to a video display device for display to a user.

A computer graphics system, comprising:

• a frame buffer;
• a texture mapping module, coupled to said frame buffer, to construct an image and to store said image in said frame buffer;
• a video display device;
• and
• a video interface, coupled to said frame buffer and said video display device, to retrieve said image from said frame buffer and to display said retrieved image on said video display device;
• wherein said texture mapping module comprises:
• mapping means for mapping a pixel from an image space to a sample point in a texture space;
• texel identifying means for identifying three texels in said texture space forming a triangular region enclosing said sample point;
• and
• calculating means for calculating a texture related value of said pixel mapped to said sample point in said texture space by triangular interpolating on corresponding texture related values of said three texels, said texture related value being a portion of said image.

A texture mapping module in a computer graphics system, said texture mapping module comprising:

• means for mapping a pixel from an image space to a sample point in a texture space, said sample point having coordinates (si+sf, ti+tf);
• means for identifying three texels in said texture space forming a triangular region enclosing said sample point;
• region determining means for determining whether said triangular region represents a lower region or an upper region;
• means for calculating a texture related value of said pixel mapped to said sample point by triangular interpolating on corresponding texture related values of said three texels according to a first equation if said triangular region represents a lower region:
• texture related value=texel›s,t!+(texel›s+1,t!-texel›s,t!) * sf+(texel›s,t+1!-texel›s,t!) * tf;
• and
• means for calculating a texture related value of said pixel mapped to said sample point by triangular interpolating on corresponding texture related values of said three texels according to a second equation if said triangular region represents a lower region:
• ##EQU11##

A computer program product comprising a computer useable medium having computer program logic recorded thereon for enabling a processor in a computer system to perform texture mapping using triangular interpolation, said computer program logic comprising:

• means for enabling said processor to map a pixel from an image space to a sample point in a texture space, said sample point having coordinates (si+sf, ti+tf);
• means for enabling said processor to identify three texels in said texture space forming a triangular region enclosing said sample point;
• region determining means for enabling said processor to determine whether said triangular region represents a lower region or an upper region;
• means for enabling said processor to calculate a texture related value of said pixel mapped to said sample point by triangular interpolating on corresponding texture related values-of said three texels according to a first equation if said triangular region represents a lower region:
• texture related value=texel›s,t!+(texel›s+1,t!-texel›s,t!) * sf+(texel›s,t+1!-texel›s,t!) * tf;
• and
• means for enabling said processor to calculate a texture related value of said pixel mapped to said sample point by triangular interpolating on corresponding texture related values of said three texels according to a second equation if said triangular region represents a lower region:
• ##EQU12##