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/* Copyright (c) 1995 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* pmapgen.c: general routines for 2-D perspective mappings. |
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* These routines are independent of the poly structure, |
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#define TOLERANCE 1e-13 |
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#define ZERO(x) ((x)<TOLERANCE && (x)>-TOLERANCE) |
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#define X(i) quad[i][0] /* quadrilateral x and y */ |
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#define Y(i) quad[i][1] |
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#define X(i) qdrl[i][0] /* quadrilateral x and y */ |
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#define Y(i) qdrl[i][1] |
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/* |
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* pmap_quad_rect: find mapping between quadrilateral and rectangle. |
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* The correspondence is: |
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* |
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* quad[0] --> (u0,v0) |
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* quad[1] --> (u1,v0) |
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* quad[2] --> (u1,v1) |
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* quad[3] --> (u0,v1) |
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* qdrl[0] --> (u0,v0) |
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* qdrl[1] --> (u1,v0) |
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* qdrl[2] --> (u1,v1) |
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* qdrl[3] --> (u0,v1) |
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* |
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* This method of computing the adjoint numerically is cheaper than |
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* computing it symbolically. |
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*/ |
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pmap_quad_rect(u0, v0, u1, v1, quad, QR) |
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pmap_quad_rect(u0, v0, u1, v1, qdrl, QR) |
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double u0, v0, u1, v1; /* bounds of rectangle */ |
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double quad[4][2]; /* vertices of quadrilateral */ |
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double QR[3][3]; /* quad->rect transform (returned) */ |
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double qdrl[4][2]; /* vertices of quadrilateral */ |
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double QR[3][3]; /* qdrl->rect transform (returned) */ |
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{ |
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int ret; |
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double du, dv; |
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double RQ[3][3]; /* rect->quad transform */ |
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double RQ[3][3]; /* rect->qdrl transform */ |
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du = u1-u0; |
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dv = v1-v0; |
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} |
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/* first find mapping from unit uv square to xy quadrilateral */ |
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ret = pmap_square_quad(quad, RQ); |
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ret = pmap_square_quad(qdrl, RQ); |
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if (ret==PMAP_BAD) return PMAP_BAD; |
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/* concatenate transform from uv rectangle (u0,v0,u1,v1) to unit square */ |
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* pmap_square_quad: find mapping between unit square and quadrilateral. |
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* The correspondence is: |
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* |
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* (0,0) --> quad[0] |
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* (1,0) --> quad[1] |
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* (1,1) --> quad[2] |
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* (0,1) --> quad[3] |
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* (0,0) --> qdrl[0] |
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* (1,0) --> qdrl[1] |
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* (1,1) --> qdrl[2] |
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* (0,1) --> qdrl[3] |
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*/ |
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pmap_square_quad(quad, SQ) |
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register double quad[4][2]; /* vertices of quadrilateral */ |
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register double SQ[3][3]; /* square->quad transform */ |
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pmap_square_quad(qdrl, SQ) |
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register double qdrl[4][2]; /* vertices of quadrilateral */ |
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register double SQ[3][3]; /* square->qdrl transform */ |
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{ |
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double px, py; |
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