Environment mapping
View Patent ↗A system and method for environment mapping determines a computer-generated object's reflective appearance, based upon position and orientation of a camera with respect to the object's location. An embodiment of the present invention is implemented as a real-time environment mapping for polygon rendering, however, the scope of the invention covers other rendering schemes. According to one embodiment of the present invention, a vector processing unit (VPU) uses a modified reflection formula—r=e−(e·(n+e o ))(n+e o )/(1−nz)=e−(e·[nx, ny, nz−1])[nx, ny, nz−1]/(1−nz), wherein e o =[0,0,−1], and nx, ny, and nz are the components of the surface normal vector n—to compute reflective properties of an object.
1. A system for environment mapping of a surface of a reflective object, the system comprising:
memory to store a reflection formula that substitutes a pseudo-normal vector for a normal vector at a point on the surface, and wherein the pseudo-normal vector is defined as bisecting an observation vector directed to an observer and the normal vector;
a vector processing unit that computes reflection vectors based on the reflection formula; and
a graphics processing unit that renders the reflective object in an image based on-the computed reflection vectors.
2. The system of claim 1 , wherein the reflection formula is r =e−(e·[nx, ny, nz −1])[nx, ny, nz−1]/(1 −nz), and where nx, ny, and nz are components of the normal vector n at a point on the surface, and e is an observation vector directed from the point on the surface to the observer.
3. The system of claim 1 , wherein the observation vector is a unit observation vector with a magnitude of 1.
4. The system of claim 1 , wherein the normal vector is a unit normal vector with a magnitude of 1.
5. The system of claim 1 , wherein the reflection formula is r =e−(e·(n+e0))(n+e0)/(1−nz), and where n is the normal vector at a point on the surface, e is an observation vector directed from the point to the observer, and e 0 is coordinate [0,0,−1] directly in front of the observer.
6. The system of claim 1 , wherein the vector processing unit generates texture coordinates (s,t) based on a computed reflection vector.
7. The system of claim 6 , wherein the graphics processing unit that renders the reflective object in an image is further based on the generated texture coordinates.
8. The system of claim 1 , wherein the graphics processing unit renders the reflective object in an image in real-time.
9. A method for displaying an image of a reflective object, comprising:
selecting a vertex on a surface of a reflective object;
determining a normal vector of the selected vertex;
determining an observation vector directed to an observer;
generating a reflection vector using a reflection formula based on a pseudo-normal vector, wherein the pseudo-normal vector bisects the normal vector and the observation vector;
computing texture coordinates based on the generated reflection vector; and
preparing the image of the reflective object for display on a display device based upon the computed texture coordinates.
10. The method of claim 9 , wherein the reflection formula substitutes the pseudo-normal vector for the normal vector in a regular environment reflection projection formula of r =e−2(e·n)n, where n is the normal vector at a point on the surface, and e is an observation vector directed from the point to the observer.
11. The method of claim 9 , wherein the observation vector is computed.
12. The method of claim 9 , wherein the observation vector is received from memory.
13. The method of claim 9 , wherein the observation vector is received from registers.