Shadow casting

Hi ,
My model needs to cast and receive shadows. How do I do this. Do I have to test each polygon with every other polygon and calculate the shadow polygon. My models generally have about 5,000 polygons and if I have to do the test i mentioned it would be very very slow to render the image. With 2 or more lights it will be a dead slow.
Please help me in getting started.



You can try shadow buffers, shadow volumes, ground plane shadows, etc. There are examples on nvidia’s dev site on the shadow buffers and volumes. Somewhere on this site is a tutorial on using the stencil buffer to make simple ground plane shadows which i think are about the easiest but only cast a shadow on the ground. Personally i like shadow volumes the best, but they are not exactly the easiest shadowing technique to use either. Well to get working correctly and without shadow errors.