C++ 如何在 OpenGL 中使用 alpha 透明度？
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How to use alpha transparency in OpenGL?
提问by H-H
Here's my code:
这是我的代码：
void display(void);
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGBA);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable( GL_BLEND );
glutInitWindowSize(600,600);
glutInitWindowPosition(200,50);
glutCreateWindow("glut test");
glutDisplayFunc(display);
glutMainLoop();
return 0;
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
glPointSize(8);
glBegin(GL_POINTS);
glColor4f(.23,.78,.32,1.0);
glVertex2f(0,0);
glColor4f(.23,.78,.32,0.1);
glVertex2f(0.1,0);
glEnd();
glFlush();
}
The problem is that these two points appear identical (even when I set the alpha to 0). Is there something I missed to enable alpha transparency?
问题是这两个点看起来相同（即使我将 alpha 设置为 0）。我错过了启用 alpha 透明度的功能吗？
采纳答案by Andrew Keith
Just a guess, but could it be that you dont have a background color ? So, when your rendering the second vertex which has alpha 0.1, there is no background to compute the proper color ? Just a guess, been years since i used opengl.
只是一个猜测，但可能是你没有背景颜色？那么，当您渲染具有 alpha 0.1 的第二个顶点时，没有背景来计算正确的颜色？只是一个猜测，自从我使用 opengl 已经好几年了。
回答by Goz
have you glEnable'd alpha blending? And have you set up your blend parameters? You can't just set the alpha you need to setup various other parameters in OpenGL.
你有glEnable'd alpha混合吗？您是否设置了混合参数？您不能只设置在 OpenGL 中设置各种其他参数所需的 alpha。
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable( GL_BLEND );
