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https://github.com/UpsilonNumworks/Upsilon.git
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2778ccea11
The screen size used to be defined by the framebuffer size, this was weird, the creen size can be defined in the makefile if needed (in order to have different one for different targets) Change-Id: Ie294fba5f6cf5e942b4b35847ae8ccd18d3ddf85
61 lines
1.4 KiB
C
61 lines
1.4 KiB
C
#include <kandinsky/line.h>
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#include <kandinsky/pixel.h>
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#include <assert.h>
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void KDDrawLine(KDPoint p1, KDPoint p2, KDColor c) {
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// Find the largest gap
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KDPoint left, right;
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if (p2.x > p1.x) {
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left = p1;
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right = p2;
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} else {
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left = p2;
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right = p1;
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}
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KDPoint top, bottom;
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if (p2.y > p1.y) {
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top = p1;
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bottom = p2;
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} else {
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top = p2;
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bottom = p1;
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}
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assert(right.x >= left.x);
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assert(bottom.y >= top.y);
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KDCoordinate deltaX = 2*(right.x - left.x);
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KDCoordinate deltaY = 2*(bottom.y - top.y);
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KDPoint p, alwaysTranslate, conditionalTranslate;
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KDCoordinate scanLength, error, minusError, plusError;
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if (deltaX >= deltaY) {
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p = left;
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scanLength = right.x - left.x;
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error = right.x - left.x;
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minusError = deltaY;
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plusError = deltaX;
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alwaysTranslate = KDPointMake(1,0);
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conditionalTranslate = KDPointMake(0, (right.y >= left.y ? 1 : -1));
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} else {
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p = top;
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scanLength = bottom.y - top.y;
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error = bottom.y - top.y;
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minusError = deltaX;
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plusError = deltaY;
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alwaysTranslate = KDPointMake(0,1);
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conditionalTranslate = KDPointMake((bottom.x >= top.x ? 1 : -1), 0);
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}
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KDCoordinate scanCounter = 0;
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while (scanCounter++ < scanLength) {
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KDSetPixel(p, c);
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p = KDPointTranslate(p, alwaysTranslate);
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error = error - minusError;
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if (error <= 0) {
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p = KDPointTranslate(p, conditionalTranslate);
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error = error + plusError;
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}
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}
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}
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