Function Tile_GetDirection

src/tile.c:342–396

* Get to direction to follow to go from \a from to \a to. * * @param from The origin. * @param to The destination. * @return The direction. */

 * @return The direction.
 */
int8 Tile_GetDirection(tile32 from, tile32 to)
{
	static const uint16 orientationOffsets[] = {0x40, 0x80, 0x0, 0xC0};
	static const int32 directions[] = {
			0x3FFF, 0x28BC, 0x145A, 0xD8E,  0xA27, 0x81B, 0x6BD, 0x5C3,  0x506, 0x474, 0x3FE, 0x39D,  0x34B, 0x306, 0x2CB, 0x297,
			0x26A,  0x241,  0x21D,  0x1FC,  0x1DE, 0x1C3, 0x1AB, 0x194,  0x17F, 0x16B, 0x159, 0x148,  0x137, 0x128, 0x11A, 0x10C
	};

	int32 dx;
	int32 dy;
	uint16 i;
	int32 gradient;
	uint16 baseOrientation;
	bool invert;
	uint16 quadrant = 0;

	dx = to.x - from.x;
	dy = to.y - from.y;

	if (abs(dx) + abs(dy) > 8000) {
		dx /= 2;
		dy /= 2;
	}

	if (dy <= 0) {
		quadrant |= 0x2;
		dy = -dy;
	}

	if (dx < 0) {
		quadrant |= 0x1;
		dx = -dx;
	}

	baseOrientation = orientationOffsets[quadrant];
	invert = false;
	gradient = 0x7FFF;

	if (dx >= dy) {
		if (dy != 0) gradient = (dx << 8) / dy;
	} else {
		invert = true;
		if (dx != 0) gradient = (dy << 8) / dx;
	}

	for (i = 0; i < lengthof(directions); i++) {
		if (directions[i] <= gradient) break;
	}

	if (!invert) i = 64 - i;

	if (quadrant == 0 || quadrant == 3) return (baseOrientation + 64 - i) & 0xFF;

	return (baseOrientation + i) & 0xFF;
}

/**
 * Move to the given orientation looking from the current position.