Hardware accelerated simulation of atmospheric scattering

1. A method comprising:

calculating a view ray for a pixel of a graphical scene, wherein the calculating is conducted by a software module;

sending parameters of the view ray to a hardware texture unit;

selecting a plurality of sample locations along the view ray based on the parameters;

comparing the plurality of sample locations to a shadow texture to obtain a corresponding plurality of illumination values;

summing the plurality of illumination values to obtain an illumination of the view ray, wherein the selecting, comparing and summing are conducted by the hardware texture unit; and

sending the illumination to the software module.

2. The method of claim 1 , wherein the parameters of the view ray include a three-dimensional initial position, a three-dimensional set of gradients, a ray length, and a number of samples to be evaluated.

3. The method of claim 1 , further including weighting the plurality of illumination values.

4. The method of claim 1 , further including fetching portions of the shadow texture from a graphics memory based on the parameters of the view ray.

5. The method of claim 1 , wherein the illumination indicates an illumination percentage for the view ray.

6. The method of claim 1 , further including rendering the pixel based on the illumination of the view ray, wherein the rendering is conducted by the software module.

7. A system comprising:

a hardware texture unit having logic to:

receive parameters of a view ray for a pixel of a graphical scene,

determine an illumination of the view ray,

select a plurality of sample locations along the view ray based on the parameters,

compare the plurality of sample locations to a shadow texture to obtain a corresponding plurality of illumination values, and

sum the plurality of illumination values to obtain the illumination of the view ray.

8. The system of claim 7 , wherein the parameters of the view ray are to include a three-dimensional initial position, a three-dimensional set of gradients, and a ray length.

9. The system of claim 8 , wherein the parameters of the view ray are to further include a number of samples to be evaluated.

10. The system of claim 7 , wherein the hardware texture unit further includes logic to weight the plurality of illumination values.

11. The system of claim 7 , further including a graphics memory coupled to the hardware texture unit, the graphics memory to store the shadow texture and the hardware texture unit to include logic to fetch portions of the shadow texture from the graphics memory based on the parameters of the view ray.

12. The system of claim 7 , wherein the hardware texture unit includes logic to receive the parameters of the view ray from a software module.

13. The system of claim 7 , wherein the hardware texture unit includes logic to send the illumination of the view ray to a software module.

14. The system of claim 7 , wherein the illumination is to indicate an illumination percentage for the view ray.

15. A non-transitory computer readable storage medium comprising a set of stored instructions which, if executed by a processor, cause a computer to:

calculate a view ray for a pixel of a graphical scene;

send parameters of the view ray to a hardware texture unit; and

receive an illumination of the view ray from the hardware texture unit,

wherein the parameters of the view ray are to include a three-dimensional initial position, a three-dimensional set of gradients, and a ray length.

16. The medium of claim 15 , wherein the parameters of the view ray are to further include a number of samples to be evaluated.

17. The medium of claim 15 , wherein the instructions, if executed, further cause a computer to render the pixel based on the illumination of the view ray.

18. The medium of claim 15 , wherein the illumination is to indicate an in-scatter illumination percentage for the view ray.