OpenGL颜色矩阵 [英] OpenGL Color Matrix

问题描述

如何获得OpenGL颜色矩阵变换？

How do I get the OpenGL color matrix transforms working?

我修改了一个只绘制三角形的示例程序，并添加了一些颜色矩阵代码如果我可以改变三角形的颜色，但它似乎不工作。

I've modified a sample program that just draws a triangle, and added some color matrix code to see if I can change the colors of the triangle but it doesn't seem to work.

    static float theta = 0.0f;
glClearColor( 1.0f, 1.0f, 1.0f, 1.0f );
glClearDepth(1.0);
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glPushMatrix();
glRotatef( theta, 0.0f, 0.0f, 1.0f );
glMatrixMode(GL_COLOR);

GLfloat rgbconversion[16] = 
{
	0.0f, 0.0f, 0.0f, 0.0f,
	0.0f, 0.0f, 0.0f, 0.0f,
	0.0f, 0.0f, 0.0f, 0.0f,
	0.0f, 0.0f, 0.0f, 0.0f
};
glLoadMatrixf(rgbconversion);
glMatrixMode(GL_MODELVIEW);

glBegin( GL_TRIANGLES );
glColor3f( 1.0f, 0.0f, 0.0f ); glVertex3f( 0.0f, 1.0f , 0.5f);
glColor3f( 0.0f, 1.0f, 0.0f ); glVertex3f( 0.87f, -0.5f, 0.5f );
glColor3f( 0.0f, 0.0f, 1.0f ); glVertex3f( -0.87f, -0.5f, 0.5f );
glEnd();
glPopMatrix();

据我所知，我加载的颜色矩阵应该将三角形更改为黑色，但它似乎没有工作。是否有我缺少的东西？

As far as I can tell, the color matrix I'm loading should change the triangle to black, but it doesn't seem to work. Is there something I'm missing?

推荐答案

颜色矩阵只适用于像素传输操作，如glDrawPixels，加速当前硬件。然而，使用片段着色器实现颜色矩阵真的很容易。你可以把你的矩阵作为一个统一的mat4，然后多用 gl_FragColor

The color matrix only applies to pixel transfer operations such as glDrawPixels which aren't hardware accelerated on current hardware. However, implementing a color matrix using a fragment shader is really easy. You can just pass your matrix as a uniform mat4 then mulitply it with gl_FragColor

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