[GLSL]求助:怎样写gl_FragColor ?

Jedimaster

我知道可以混合颜色

c1 = texture2D(tex1,gl_TexCoord[0]);
c2 = texture2D(tex2,gl_TexCoord[1]);
比如gl_FragColor = (c1+c2)*0.5;

可是这是体现的却是混合的效果

如果我在程序里已经给一个多边形绑定上不同的坐标
glBegin(GL_QUADS);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 0.0, 1.0);glMultiTexCoord2fARB(GL_TEXTURE1_ARB, 0.0, 1.0);
glVertex3f(0.0f,0.0f,0.0f);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 0.0, 0.0);glMultiTexCoord2fARB(GL_TEXTURE1_ARB, 0.0, 0.0);
glVertex3f(1.0f,0.0f,0.0f);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 1.0, 0.0);glMultiTexCoord2fARB(GL_TEXTURE1_ARB, 1.0, 0.0);
glVertex3f(1.0f,1.0f,0.0f);
glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 1.0, 1.0);glMultiTexCoord2fARBglVertex3f(0.0f,1.0f,0.0f);
glEnd();

现在我想显示2个正方形，用不同的纹理，程序也是很好写的

但是，gl_FragColor怎么写？难道还是c1+c2？这个不可能吧

求助达人，谢谢 [em1] [em1]