Cleanup, add scanline mask builder

PortabilityLayer/LinePlotter.cpp

@@ -0,0 +1,101 @@
+#include "LinePlotter.h"
+#include "Vec2i.h"
+
+#include <assert.h>
+
+namespace PortabilityLayer
+{
+	LinePlotter::LinePlotter()
+		: m_point(0, 0)
+		, m_endPoint(0, 0)
+		, m_dx(0)
+		, m_dy(0)
+		, m_err(0)
+		, m_xIncrPos(true)
+		, m_yIncrPos(true)
+		, m_xMove(PlotDirection_Exhausted)
+		, m_yMove(PlotDirection_Exhausted)
+		, m_xyMove(PlotDirection_Exhausted)
+	{
+	}
+
+	PlotDirection LinePlotter::PlotNext()
+	{
+		if (m_point == m_endPoint)
+			return PlotDirection_Exhausted;
+
+		bool movedX = false;
+		const int32_t err2 = 2 * m_err;
+		if (err2 >= m_dy)
+		{
+			m_err += m_dy;
+			m_point.m_x += m_xIncrPos ? 1 : -1;
+			movedX = true;
+		}
+
+		if (err2 <= m_dx)
+		{
+			m_err += m_dx;
+			m_point.m_y += m_yIncrPos ? 1 : -1;
+
+			if (movedX)
+				return m_xyMove;
+			else
+				return m_yMove;
+		}
+		else
+		{
+			assert(movedX);
+			return m_xMove;
+		}
+	}
+
+	const Vec2i &LinePlotter::GetPoint() const
+	{
+		return m_point;
+	}
+
+	void LinePlotter::Reset(const Vec2i &pointA, const Vec2i &pointB)
+	{
+		m_dx = pointB.m_x - pointA.m_x;
+		if (m_dx < 0)
+			m_dx = -m_dx;
+
+		m_dy = pointB.m_y - pointA.m_y;
+		if (m_dy > 0)
+			m_dy = -m_dy;
+
+		m_xIncrPos = (pointA.m_x < pointB.m_x);
+		m_yIncrPos = (pointA.m_y < pointB.m_y);
+
+		m_err = m_dx + m_dy;
+
+		m_point = pointA;
+		m_endPoint = pointB;
+
+		if (m_xIncrPos)
+		{
+			if (m_yIncrPos)
+				m_xyMove = PlotDirection_PosX_PosY;
+			else
+				m_xyMove = PlotDirection_PosX_NegY;
+
+			m_xMove = PlotDirection_PosX_0Y;
+		}
+		else
+		{
+			if (m_yIncrPos)
+				m_xyMove = PlotDirection_NegX_PosY;
+			else
+				m_xyMove = PlotDirection_NegX_NegY;
+
+			m_xMove = PlotDirection_NegX_0Y;
+		}
+
+
+		if (m_yIncrPos)
+			m_yMove = PlotDirection_0X_PosY;
+		else
+			m_yMove = PlotDirection_0X_NegY;
+	}
+}