103 lines
2.1 KiB
C++
103 lines
2.1 KiB
C++
#include "Rasterizer.h"
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#include <Vector2.h>
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#include "Color.h"
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#include <cmath>
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#include <cstdint>
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namespace Rasterizer
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{
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using namespace Math;
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using namespace RenderData;
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void Rasterizer::DrawLineHorizontal(const Vector2Int v0, const Vector2Int v1, const Color color)
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{
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Vector2Int start = v0, end = v1;
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if (v0.x > v1.x)
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{
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start = v1;
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end = v0;
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}
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int32_t dx = end.x - start.x;
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int32_t dy = end.y - start.y;
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int32_t dir = dy < 0 ? -1 : 1;
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dy *= dir;
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if (dx == 0) return;
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int32_t y = start.y;
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int32_t p = 2 * dy - dx;
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for (int32_t x = start.x; x <= end.x; x++)
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{
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frameBuffer->set_pixel(x, y, color.to_rgba());
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// 当 p >= 0 时，取上方像素点
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if (p >= 0)
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{
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y += dir;
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p -= 2 * dx;
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}
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// 当 p < 0 时，取下方像素点
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p += 2 * dy;
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}
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}
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void Rasterizer::DrawLineVertical(const Vector2Int v0, const Vector2Int v1, const Color color)
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{
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Vector2Int start = v0, end = v1;
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if (v0.y > v1.y)
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{
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start = v1;
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end = v0;
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}
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int32_t dx = end.x - start.x;
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int32_t dy = end.y - start.y;
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int32_t dir = dx < 0 ? -1 : 1;
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dx *= dir;
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if (dy == 0) return;
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int32_t x = start.x;
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int32_t p = 2 * dx - dy;
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for (int32_t y = start.y; y <= end.y; y++)
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{
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frameBuffer->set_pixel(x, y, color.to_rgba());
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// 当 p >= 0 时，取上方像素点
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if (p >= 0)
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{
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x += dir;
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p -= 2 * dy;
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}
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// 当 p < 0 时，取下方像素点
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p += 2 * dx;
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}
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}
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/// <summary>
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/// 在给定的起始点和结束点之间绘制一条线段，并使用指定的颜色填充
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/// </summary>
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/// <param name="v0">直线顶点 1</param>
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/// <param name="v1">直线顶点 2</param>
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/// <param name="color">绘制的颜色</param>
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/// <remarks>
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/// bresenham 画线算法
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/// </remarks>
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void Rasterizer::DrawLine(const Vector2Int v0, const Vector2Int v1, const Color color)
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{
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int32_t x0 = v0.x, y0 = v0.y;
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int32_t x1 = v1.x, y1 = v1.y;
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if (std::abs(x1 - x0) > std::abs(y1 - y0))
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{
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DrawLineHorizontal(v0, v1, color);
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}
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else
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{
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DrawLineVertical(v0, v1, color);
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}
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}
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}
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