An attempt to implement thick line drawing.

svn-id: r29639

1 files changed, 55 insertions, 0 deletions

diff --git a/graphics/primitives.cpp b/graphics/primitives.cpp
index 9fdcb13b7b..85a0383ea9 100644
--- a/graphics/primitives.cpp
+++ b/graphics/primitives.cpp
@@ -64,4 +64,59 @@ void drawLine(int x0, int y0, int x1, int y1, int color, void (*plotProc)(int, i
 	}
 }
 
+
+// FIXME: This is a limited version of thick line drawing
+// it draws striped lines at some angles. Better algorithm could
+// be found here:
+//
+//   http://homepages.enterprise.net/murphy/thickline/index.html
+//
+// Feel free to replace it with better implementation
+void drawThickLine(int x0, int y0, int x1, int y1, int thickness, int color, void (*plotProc)(int, int, int, void *), void *data) {
+	const bool steep = ABS(y1 - y0) > ABS(x1 - x0);
+
+	if (steep) {
+		SWAP(x0, y0);
+		SWAP(x1, y1);
+	}
+
+	float dx = x1 - x0;
+	float dy = y1 - y0;
+	float d = sqrtf(dx * dx + dy * dy);
+
+	if (!d)
+        return;
+
+	int thickX = (int)((float)thickness * dy / d / 2);
+	int thickY = (int)((float)thickness * dx / d / 2);
+
+	const int delta_x = ABS(x1 - x0);
+	const int delta_y = ABS(y1 - y0);
+	const int delta_err = delta_y;
+	int x = x0;
+	int y = y0;
+	int err = 0;
+
+	const int x_step = (x0 < x1) ? 1 : -1;
+	const int y_step = (y0 < y1) ? 1 : -1;
+
+	if (steep)
+		drawLine(y - thickY, x + thickX, y + thickY, x - thickX, color, plotProc, data);
+	else
+		drawLine(x - thickX, y + thickY, x + thickX, y - thickY, color, plotProc, data);
+
+	while (x != x1) {
+		x += x_step;
+		err += delta_err;
+		if (2 * err > delta_x) {
+			y += y_step;
+			err -= delta_x;
+		}
+		if (steep)
+			drawLine(y - thickY, x + thickX, y + thickY, x - thickX, color, plotProc, data);
+		else
+			drawLine(x - thickX, y + thickY, x + thickX, y - thickY, color, plotProc, data);
+	}
+}
+
 }	// End of namespace Graphics