1 files changed, 44 insertions, 0 deletions
diff --git a/FrameRender/P_LineSegment.c b/FrameRender/P_LineSegment.c
new file mode 100644
index 0000000..f2236ff
--- /dev/null
+++ b/FrameRender/P_LineSegment.c
@@ -0,0 +1,44 @@
+#include "P_LineSegment.h"
+#include "PixelCallback.h"
+#include <math.h>
+#include <stdlib.h>
+#include <string.h>
+
+void rotatePoint(i32* x, i32* y, double angle) {
+	i32 xR = *x * cos(angle) + *y * sin(angle);
+	i32 yR = - *x * sin(angle) + *y * cos(angle);
+	*x = xR;
+	*y = yR;
+}
+
+void LineSegment_callback(LineSegment* self, struct PixelContext* fc) {
+	/* IDK if this is the most efficient, online results seem
+	 * to do more complicated calculations.
+	 * Center coordianates around aX,aY
+	 * Then unrotate bX,bY and x,y relative to 0,0 (aX,aY),
+	 * so that bX,bY lies on the horizontal axis.
+	 * Now the line is flat from 0,0 to the "right" (increasing x).
+	 */
+	i32 x = fc->x - self->aX, y = fc->y - self->aY;
+	i32 bX = self->bX - self->aX, bY = self->bY - self->aY;
+
+	double phi = atan2(bY, bX);
+	rotatePoint(&y, &x, -phi);
+	rotatePoint(&bY, &bX, -phi);
+
+	if (0 <= x && x <= bX &&
+	    -(i32)self->width / 2 <= y && y <= self->width / 2)
+	{
+		ARGB_merge(&fc->pixel, self->color);
+	}
+}
+
+PixelCallback* LineSegment_setup(LineSegment obj) {
+	PixelCallback* pca = malloc(sizeof(struct PixelCallback));
+
+	pca->callback = (PixelCallback_callback)LineSegment_callback;
+	pca->callback_self = malloc(sizeof(obj));
+	memcpy(pca->callback_self, &obj, sizeof(obj));
+
+	return pca;
+}