[游戏开发]【C++】 UV 转 RGB 生成风力图

风力图样式是这样的：

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我用的海流的数据，绘制海流的流线，但我的数据是海流的U分量和V分量，做了UV转RG的转换，B为0，?代码如下：

void UV2RG(float fU, float fV, int &nR, int &nG)
{
	double dPI = 3.1415926;
	//流向
	float direction = (float)((((float)atan2(fU, fV)) * 180 / dPI));
	if (direction < 0)
		direction = 360 + direction;
	
	if (direction >= 0.0f && direction < 45.0f)
	{
		nR = 127 + 127 * (direction / (45 - 0));
		nG = 255;
	}
	else if (direction >= 45.0f && direction < 135.0f)
	{
		nR = 255;
		nG = 255 - 255 * ((direction-45) / (135 - 45));
	}
	else if (direction >= 135.0f && direction < 225.0f)
	{
		nR = 255 - 255 * ((direction - 135) / (225 - 135));
		nG = 0;
	}
	else if (direction >= 225.0f && direction < 315.0f)
	{
		nR = 0;
		nG = 0 + 255 * ((direction - 225) / (315 - 225));
	}
	else if (direction >= 315.0f && direction < 360.0f)
	{
		nR = 127 * ((direction - 315) / (360 - 315));
		nG = 255;
	}
}

最终绘制出图片效果如下：

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