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