| 1 |
greg |
1.1 |
{
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| 2 |
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Calculation of 2d picture coordinates.
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| 3 |
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Picture is projected onto xy plane with lower left corner at origin.
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| 4 |
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| 5 |
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A1 - Ratio of height to width for tiles.
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| 6 |
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A2 - Average red value for fadered or grey for fadegrey
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| 7 |
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A3 - Average green value for fadegreen
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| 8 |
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A4 - Average blue value for fadeblue
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| 9 |
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A2, A3, A4 - Chroma key color for mixpict
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| 10 |
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}
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| 11 |
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{ straight coordinates }
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| 12 |
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pic_u = Px;
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| 13 |
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pic_v = Py;
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| 14 |
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{ picture aspect ratio }
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| 15 |
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pic_aspect = if(arg(0)-.5, arg(1), 1);
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{ compute borders for mixture }
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| 17 |
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inpic = if(and(pic_u, and(pic_v,
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| 18 |
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if(pic_aspect-1, and(1-pic_u,pic_aspect-pic_v),
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| 19 |
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and(1/pic_aspect-pic_u,1-pic_v) ) ) ), 1, 0);
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| 20 |
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{ chroma-key mixing }
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| 21 |
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chroma_sum`P = A2 + A3 + A4;
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| 22 |
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chroma_tol`P = 0.02 * chroma_sum`P;
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| 23 |
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intol`P(a,b) : and(a-b+chroma_tol`P, b-a+chroma_tol`P);
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| 24 |
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ischroma`P(r,g,s) = if(FTINY-chroma_sum`P, .001-s,
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if(.001-s, -1,
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and(intol`P(r*chroma_sum`P,A2*s),intol`P(g*chroma_sum`P,A3*s))
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| 27 |
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) );
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| 28 |
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infore(r,g,b) = if(inpic-.5, if(ischroma`P(r,g,r+g+b), 0, 1), 0);
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| 29 |
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{ standard tiling }
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tile_u = mod(pic_u,max(1,1/pic_aspect));
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tile_v = mod(pic_v,max(1,pic_aspect));
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| 32 |
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{ tiling with inversion matching }
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match_u = tri(pic_u,max(1,1/pic_aspect));
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match_v = tri(pic_v,max(1,pic_aspect));
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| 35 |
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{ brick-type staggering }
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| 36 |
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stag_u = if(pic_aspect-1,
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| 37 |
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frac(if(frac(pic_v/pic_aspect/2)-.5,pic_u,pic_u+.5)),
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| 38 |
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mod(if(frac(pic_v/2)-.5,pic_u,pic_u+.5/pic_aspect),
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| 39 |
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1/pic_aspect));
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| 40 |
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stag_v = tile_v;
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| 41 |
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{ fade colors for distant viewing }
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| 42 |
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fadered(r,g,b) = fade(r, A2, T*.1);
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| 43 |
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fadegreen(r,g,b) = fade(g, A3, T*.1);
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| 44 |
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fadeblue(r,g,b) = fade(b, A4, T*.1);
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| 45 |
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fadegrey(r,g,b) = fade(grey(r,g,b), A2, T*.1);
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