Efficient bump mapping using height maps
View Patent ↗A method for generating bump map data substantially in real time for use in a 3-dimensional computer graphics system. Data is received which defines an area to which a texture is to be applied. Texture data to apply to the area is also received. This data includes surface height data. A set of partially overlapping samples of texture data are then filtered and surface tangent vectors derived therefrom. A bump map surface normal is then derived from the tangent vectors.
1. A method for generating bump map data substantially in real time for use in a 3-dimensional computer graphics system comprising the steps of:
receiving data defining an area to which a texture is to be applied, using a data receiver;
receiving texture data to apply to the area, the texture data including surface height data, using a texture data receiver;
filtering each of a set of partially overlapping samples of the texture data, using a filter, the filtering step including a step of using bi-quadratic B-splines to model height surfaces from the surface height data;
deriving surface tangent vectors from the filtered samples, using a surface tangent vector generator; and
deriving a bump map surface normal from the surface tangent vectors, using a bump map surface normal generator.
2. The method according to claim 1 , wherein the tangent vectors are defined in local tangent space.
3. The method according to claim 1 , wherein the filtering step includes the step of using existing hardware in the color channels of the 3-dimensional graphics system to filter the overlapping samples of the texture data.
4. The method according to claim 1 , wherein the filtering step is modified with blending factors.
5. An apparatus for generating bump map data substantially in real time for use in a 3-dimensional computer graphics system comprising:
means for receiving data defining an area to which a texture is to be applied;
means for receiving texture data to apply to the area, the texture data including surface height data;
means for filtering each of a set of partially overlapping samples of the texture data, including means to use bi-quadratic B-splines to model height surfaces from the surface height data;
means for deriving surface tangent vectors from the filtered samples, with the surface tangent vectors being defined in local tangent space; and
means for deriving a bump map surface normal from the surface tangent vectors.
6. The apparatus according to claim 5 , wherein the filtering means includes means for using existing hardware in color channels of the 3-dimensional graphics system to filter the overlapping samples of the texture data.
7. The apparatus according to claim 5 , wherein the filtering means is modified for filtering with blending factors.
8. A method for generating bump map data for use in a 3-dimensional computer graphics system comprising the steps of:
receiving data defining an area to which a texture is to be applied, using a data receiver;
receiving texture data to apply to the area, the texture data including surface height data, using a texture data receiver;
filtering each of a set of partially overlapping samples of the texture data, using a filter, so as to model a height surface based on the surface height data;
deriving surface tangent vectors from the filtered samples, using a surface tangent vector generator; and
deriving a bump map surface normal from the surface tangent vectors, using a bump map surface normal generator.