将浮点数转换为 RGB 向量 [英] Convert a floating point number to RGB vector

问题描述

我需要用opengl渲染几个立方体，每个立方体的颜色取决于立方体中心的磁场，但我不知道如何将浮点数转换成QVector3D 或 glm::vec3 (RGB).

而且我可以在0到1之间转换float数组的范围，我需要知道如何将磁场数组转换为RGB来定义颜色数组.

解决方案

如果我理解正确，那么您想用 RGB 颜色表示 [0.0, 1.0] 范围内的浮点值.
我建议将该值转换为

对于完整范围，转换为:

float value = ...;//范围 [0.0, 1.0] 内的值浮动 H = 值；浮动 R = fabs(H * 6.0f - 3.0f) - 1.0f;浮动 G = 2.0f - 晶圆厂(H * 6.0f - 2.0f)；浮动 B = 2.0f - 晶圆厂(H * 6.0f - 4.0f)；glm::vec3 颜色(std::max(0.0, std::min(1.0, R))std::max(0.0, std::min(1.0, G))std::max(0.0, std::min(1.0, B)));

如果你不想要完整的范围，例如，如果你想使用从红色到蓝色的范围，那么value必须被缩放:

float H = value * 2.0f/3.0f;

I need to render a couple of cubes by opengl, and the color of every cube depends on the the magnetic field at the center of cube, but I don't know how to convert the float number into the QVector3D or glm::vec3 (RGB).

And I can convert the range of the float array between 0 and 1， I need to know how to convert the magnetic field array to RGB to define the color array.

解决方案

If I understand correctly, then you want to represent a floating point value in the range [0.0, 1.0], by a RGB color.
I recommend to transform the value to the HSV color range.

For the full range the conversion is:

float value = ...; // value in range [0.0, 1.0]

float H = value;
float R = fabs(H * 6.0f - 3.0f) - 1.0f;
float G = 2.0f - fabs(H * 6.0f - 2.0f);
float B = 2.0f - fabs(H * 6.0f - 4.0f);  

glm::vec3 color( 
    std::max(0.0, std::min(1.0, R))
    std::max(0.0, std::min(1.0, G))
    std::max(0.0, std::min(1.0, B)));

If you don't want the full range, for example, if you want to use the range from red to blue, then value has to be scaled:

float H = value * 2.0f/3.0f;

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