C++ 的颜色图库将给定值转换为红色、绿色和蓝色值

Question

我正在寻找一个颜色图库，它将给定值转换为红色、绿色和蓝色值。类似于matlab的colormap功能[1]。最好是 C++ 语言。

[1] http://www.mathworks.com/help/techdoc/ref/颜色图.html

Answer 1

我个人认为这对于一个库来说太简单了，我自己实现了它，他们是 C++ 中的示例（您可以查找维基百科以获取数学解释）：

/* 
* Computes the color gradiant
* color: the output vector 
* x: the gradiant (beetween 0 and 360)
* min and max: variation of the RGB channels (Move3D 0 -> 1)
*/

void GroundColorMix(double* color, double x, double min, double max)
{
   /*
    * Red = 0
    * Green = 1
    * Blue = 2
    */
    double posSlope = (max-min)/60;
    double negSlope = (min-max)/60;

    if( x < 60 )
    {
        color[0] = max;
        color[1] = posSlope*x+min;
        color[2] = min;
        return;
    }
    else if ( x < 120 )
    {
        color[0] = negSlope*x+2*max+min;
        color[1] = max;
        color[2] = min;
        return;
    }
    else if ( x < 180  )
    {
        color[0] = min;
        color[1] = max;
        color[2] = posSlope*x-2*max+min;
        return;
    }
    else if ( x < 240  )
    {
        color[0] = min;
        color[1] = negSlope*x+4*max+min;
        color[2] = max;
        return;
    }
    else if ( x < 300  )
    {
        color[0] = posSlope*x-4*max+min;
        color[1] = min;
        color[2] = max;
        return;
    }
    else
    {
        color[0] = max;
        color[1] = min;
        color[2] = negSlope*x+6*max;
        return;
    }
}