如何读取opengl中像素的颜色 [英] How do I read the color of a pixel in opengl

问题描述

我正在尝试读取像素的颜色。但由于某种原因它不起作用



这里的代码：

I am trying to read the color of a pixel. but for some reason it doesn't work

HERE'S THE CODE :

ModelClassObject.UseShader(SelectionRender.GetShaderProgram());
			glUniformMatrix4fv(SelectionRender.GetUnifromModelID(), 1, GL_FALSE, glm::value_ptr(Model));
			glUniformMatrix4fv(SelectionRender.GetUnifromProjectionID(), 1, GL_FALSE, glm::value_ptr(Projection));
			glUniformMatrix4fv(SelectionRender.GetUniformView(), 1, GL_FALSE, glm::value_ptr(Camera.CalculateViewMatrix()));
			ModelClassObject.DrawTriangles();
			glFlush();
			glFinish();
			glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
			unsigned char data[3];
			glReadPixels(0, winHeight, winWidth, winHeight, GL_RGB, GL_UNSIGNED_BYTE, data);
			std::cout 
				<< "  R  "
				<< data[0]
				<< "  G  "
				<< data[1]
				<< "  B  "
				<< data[2] 
				<< std::endl;

输出：

data [0] = 0xcc

数据[1] = 0xcc

数据[2] = 0xcc



我尝试过： < br $> b $ b

我无法弄清楚出了什么问题...

OUTPUT :
data[0] = 0xcc
data[1] = 0xcc
data[2] = 0xcc

What I have tried:

I can't figure out what's wrong...

推荐答案

我认为第二个参数是错误的。这是函数的原型：

I think the second parameter is wrong. Here is the prototype of the function:

void glReadPixels( GLint x, 
       GLint y, 
       GLsizei width, 
       GLsizei height, 
       GLenum format, 
       GLenum type, 
       GLvoid* data );

前两个参数是开始阅读的位置。第二个参数y也应该是0，但肯定不是winHeight，因为这将是一个无效的值。 y参数最多可以是winHeight-1。

The first two parameters are the location to begin reading. The second parameter, y, should probably be 0 also but certainly not winHeight because that would be an invalid value. The y parameter can be winHeight-1 at most.

感谢您的快速响应，

我启用了十六进制。我禁用它并且它有效

Thanks for the quick response,
I had the hexadecimal enabled. I disabled it and it worked

这篇关于如何读取opengl中像素的颜色的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！