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OleKaiwalker

Shadow Volume + Vertex Program

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Hey, Why dosn''t this vertex program work? It''s supposed to extrude the vertices, if the w-component is 0 It computes the extrusion via this pos = pos * pos.w + (pos * l.w - l * pos.w) * (1 - pos.w) I didn''t borhter to include the pos * l.w part, since my lights always has a w-component of 1.0f! Anyone got any ideas? !!ARBvp1.0 # Vertex Input ATTRIB vPos = vertex.position; # Local Input #PARAM light = program.local[0]; PARAM light = {0, 5, 0, 1}; # Modelview Projection Matrix PARAM mvp[4] = {state.matrix.mvp}; # Extrude Position TEMP pos, posMultW, lMultW, posSubL, posSubLMultW, w; SUB w, 1, vPos.w; MUL posMultW, vPos, vPos.w; MUL lMultW, light, vPos.w; SUB posSubL, vPos, lMultW; MUL posSubLMultW, posSubL, w; ADD pos, posMultW, posSubLMultW; # Transform Vertex Position Into Clip Space TEMP clipSpace; DP4 clipSpace.x, mvp[0], pos; DP4 clipSpace.y, mvp[1], pos; DP4 clipSpace.z, mvp[2], pos; DP4 clipSpace.w, mvp[3], pos; PARAM yellow = {1, 1, 0, 0}; MOV result.color, yellow; MOV result.position, clipSpace; END

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copy/paste:

"!!ARBvp1.0\r\n"
"\r\n"
"ATTRIB pos = vertex.position;"
"PARAM mvp[4] = { state.matrix.mvp };"
"PARAM lightpos = program.local[4];"
"TEMP p,a;"

"MOV a.xyz, lightpos;"
"MAD p, pos.w, lightpos, -a;"
"ADD p.xyz, p, pos;"

"DP4 result.position.x, mvp[0], p;"
"DP4 result.position.y, mvp[1], p;"
"DP4 result.position.z, mvp[2], p;"
"DP4 result.position.w, mvp[3], p;"
""
"
END");


This should work.
Notice the difference from the NVidia prog. Theirs has a precision problem!

[edited by - baskuenen on November 16, 2003 5:28:30 PM]

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