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GRAPHICS: Simplify trig usage in primitives

Combined if statements and simplified trig.

cos(atan2(y,x)) = x / sqrt(x^2 + y^2) and
sin(atan2(y,x)) = y / sqrt(x^2 + y^2).
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dafioram committed Sep 8, 2018
1 parent 5d77ade commit a66e661df194963d4e649d122c33255e05a2e588
Showing with 7 additions and 12 deletions.
  1. +7 −12 graphics/primitives.cpp
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@@ -121,19 +121,16 @@ void drawThickLine2(int x1, int y1, int x2, int y2, int thick, int color, void (
if (dy <= dx) {
/* More-or-less horizontal. use wid for vertical stroke */
/* Doug Claar: watch out for NaN in atan2 (2.0.5) */
/* 2.0.12: Michael Schwartz: divide rather than multiply;
TBB: but watch out for /0! */
double ac = cos(atan2((double)dy, (double)dx));
if (ac != 0) {
wid = thick / ac;
if (dx != 0 && thick != 0) {
double ac_recip = 1/dx * sqrt(dx * dx + dy * dy); // 1 / cos(atan2((double)dy, (double)dx));
wid = thick * ac_recip;
} else {
wid = 1;
}
if (wid == 0) {
wid = 1;
}
d = 2 * dy - dx;
incr1 = 2 * dy;
incr2 = 2 * (dy - dx);
@@ -185,14 +182,12 @@ void drawThickLine2(int x1, int y1, int x2, int y2, int thick, int color, void (
/* More-or-less vertical. use wid for horizontal stroke */
/* 2.0.12: Michael Schwartz: divide rather than multiply;
TBB: but watch out for /0! */
double as = sin(atan2((double)dy, (double)dx));
if (as != 0) {
wid = thick / as;
if (dy != 0 && thick != 0) {
double as_recip = 1/dy * sqrt(dx * dx + dy * dy); // 1 / sin(atan2((double)dy, (double)dx));
wid = thick * as_recip;
} else {
wid = 1;
}
if (wid == 0)
wid = 1;
d = 2 * dx - dy;
incr1 = 2 * dx;

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