Achromatic lighting in a graphics system and method

A method of generating graphics images comprising:

• defining at least one per-vertex lighting function;
• using the lighting function to calculate at least one parameter other than color or opacity to be used in a subsequent modification of a color or opacity;
• and
• rendering an image based at least in part on the calculated parameter;
• wherein said lighting function calculates a negative parameter for back lighting.

A method of cartoon lighting comprising:

• using a lighting function to generate at least one color or opacity value;
• converting said at least one color or opacity value to at least one texture coordinate;
• using said texture coordinate in at least one texture mapping operation;
• and
• using the results of said texture mapping operation to modify the color or opacity of at least one visible surface in a dynamically generated cartoon image.

A method of cartoon lighting comprising:

• using a lighting function to generate at least one color or opacity value;
• converting said color or opacity value to at least one texture coordinate;
• using said texture coordinate in at least one texture mapping operation;
• and
• using the results of said texture mapping operation to modify the color or opacity of at least one visible surface in a dynamically generated cartoon image;
• wherein said texture coordinate can range negatively to define cartoon backlighting.

A graphics system comprising:

• a lighting data pipeline comprising at least first and second channels, said lighting data pipeline receiving per-vertex information and lighting definitions;
• and calculating lit vertex parameters in response to said per-vertex and lighting definitions;
• a texture unit coupled to said lighting data pipeline, said texture unit being responsive to at least one texture coordinate, said texture unit performing at least one texture mapping operation using at least one of said lighting data pipeline outputs as said at least one texture coordinate;
• and
• a blender coupled to said lighting data pipeline and said texture unit, said blender blending chromatic and/or opacity information obtained from said lighting data pipeline with texels obtained from said texture unit to provide a rendered image.