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adjust coords in wide_line() to be conformant

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This commit is contained in:
Brian 2007-10-23 11:38:17 -06:00
parent 112a1580f6
commit be04999982
1 changed files with 47 additions and 8 deletions
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55
src/mesa/pipe/draw/draw_wide_prims.c
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@ -100,17 +100,56 @@ static void wide_line( struct draw_stage *stage,
const float dx = FABSF(pos0[0] - pos2[0]);
const float dy = FABSF(pos0[1] - pos2[1]);
/*
* Draw wide line as a quad (two tris) by "stretching" the line along
* X or Y.
* XXX For AA lines, the quad corners have to be computed in a
* more sophisticated way.
*/
/* need to tweak coords in several ways to be conformant here */
if (dx > dy) {
pos0[1] -= half_width;
pos1[1] += half_width;
pos2[1] -= half_width;
pos3[1] += half_width;
/* x-major line */
pos0[1] = pos0[1] - half_width - 0.25;
pos1[1] = pos1[1] + half_width - 0.25;
pos2[1] = pos2[1] - half_width - 0.25;
pos3[1] = pos3[1] + half_width - 0.25;
if (pos0[0] < pos2[0]) {
/* left to right line */
pos0[0] -= 0.5;
pos1[0] -= 0.5;
pos2[0] -= 0.5;
pos3[0] -= 0.5;
}
else {
/* right to left line */
pos0[0] += 0.5;
pos1[0] += 0.5;
pos2[0] += 0.5;
pos3[0] += 0.5;
}
}
else {
pos0[0] -= half_width;
pos1[0] += half_width;
pos2[0] -= half_width;
pos3[0] += half_width;
/* y-major line */
pos0[0] = pos0[0] - half_width + 0.25;
pos1[0] = pos1[0] + half_width + 0.25;
pos2[0] = pos2[0] - half_width + 0.25;
pos3[0] = pos3[0] + half_width + 0.25;
if (pos0[1] < pos2[1]) {
/* top to bottom line */
pos0[1] -= 0.5;
pos1[1] -= 0.5;
pos2[1] -= 0.5;
pos3[1] -= 0.5;
}
else {
/* bottom to top line */
pos0[1] += 0.5;
pos1[1] += 0.5;
pos2[1] += 0.5;
pos3[1] += 0.5;
}
}
tri.det = header->det; /* only the sign matters */