Submitted by , posted on 08 September 1999

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this is a screen shot of a software renderer i am making from scratch, it is an example of the polygon rasterizer scan line interleaving (SLI) capabilities. this is very cool, easy to do, and can yield 2x or 3x performance with little visual quality loss. my current texture mapper is all coded in C and i used no papers, docs, web sites or anything, just started with algebraic equations and went from there, it actually isn't that hard once you get into it, the hard part is going to be getting exact accuracy, what i mean is now when you zoom into two polys that are adjacently mapped, the texture is off and doesn't line up correctly all the time at the crease, maybe due to round off errors, but i am almost sure it is some design error by me, if any body has some general tips for this problem please tell me about them.

i will be very interested in seeing how SLI will work in an actual game, but that will be a couple more months before i have good content and engine to test with. also, i might release the source code in the future, but not until i get everything completed with the rasterizer.

some specifics about my t mapper so far:
  • outer loop is all floating point
  • inner loop is all integer ops, currently 6 adds, 2 shifts, 2 ands, 2 assignments
  • currently affine mapped, but at huge angles there seems to be NO distortion, don't know why? but i like it!
  • y clipping per polygon, and x clipping per scan line
  • hacked bilinear filtering (this is more ops then in above)
  • texture can be any size power of 2, width and height can be different
  • texture is tileable
  • arbitrary SLI
  • email me with any questions, comments, or advise!
    james bryant

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