opengl-es - OpenGL，GL_MODULATE和多重纹理

Question

我已经成功绘制了多纹理多边形，但是不幸的是，整个纹理区域仅使用了覆盖纹理的第一个像素。

以下是纹理(GL_TEXTURE0和GL_TEXTURE1):



结果是这样的:

仅使用顶部的红色像素。我尝试过仅在顶部放置一个1x1蓝色像素，并且使用蓝色覆盖层得到相同的结果。

我的代码:

glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glDisableClientState(GL_COLOR_ARRAY);

const CGPoint vertices[] = {
    ccp(0,0),
    ccp(100,0),
    ccp(0,100),
    ccp(100,100),
};

// This will flip the image for us as well
const CGPoint coordinates[] = {
    ccp(0,1),
    ccp(1,1),
    ccp(0,0),
    ccp(1,0),
};

// Config multitextures
glClientActiveTexture(GL_TEXTURE0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, icon.name);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE); 
glTexCoordPointer(2, GL_FLOAT, 0, coordinates);
glEnable(GL_TEXTURE_2D);

glClientActiveTexture(GL_TEXTURE1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, overlay.name);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glTexCoordPointer(2, GL_FLOAT, 0, coordinates);
glEnable(GL_TEXTURE_2D);

GLubyte points = 4;

// Draw the square
glVertexPointer(2, GL_FLOAT, 0, vertices);
glDrawArrays(GL_TRIANGLE_STRIP, 0, points);

// Revert back
glActiveTexture(GL_TEXTURE1);
glDisable(GL_TEXTURE_2D);

// glClientActiveTexture(GL_TEXTURE0); // breaks multitexturing
glActiveTexture(GL_TEXTURE0);
glEnable(GL_TEXTURE_2D);

glEnableClientState(GL_COLOR_ARRAY);

这是OpenGL问题，但是有兴趣的人可以在这里找到iOS项目:http://dl.dropbox.com/u/33811812/cocos2d/OpenGLTest.zip

编辑:
从红皮书:

If you are multitexturing and you use glTexCoord*(), you are setting the texture coordinates for the first texture unit. In other words, using glTexCoord*() is equivalent to using glMultiTexCoord* (GL_TEXTURE0,...)

关于如何传递坐标数组的任何提示吗？ OpenGL ES 1.1不支持glBegin()等。

Answer 1

最后!解决的办法是我必须做三件事:

在glTexCoordPointer

之前，将glClientActiveTexture(GL_TEXTURE *)用作0和1

对每个纹理也使用glEnableClientState(GL_TEXTURE_COORD_ARRAY)以及

还原回glClientActiveTexture(GL_TEXTURE0)以避免与进一步绘制产生冲突

这是有效的代码:

glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glDisableClientState(GL_COLOR_ARRAY);

const CGPoint vertices[] = {
    ccp(0,0),
    ccp(100,0),
    ccp(0,100),
    ccp(100,100),
};

// This will flip the image for us as well
const CGPoint coordinates[] = {
    ccp(0,1),
    ccp(1,1),
    ccp(0,0),
    ccp(1,0),
};

// Config multitextures
glClientActiveTexture(GL_TEXTURE0);
glActiveTexture(GL_TEXTURE0);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glBindTexture(GL_TEXTURE_2D, icon.name);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE); 
glTexCoordPointer(2, GL_FLOAT, 0, coordinates);
glEnable(GL_TEXTURE_2D);

glClientActiveTexture(GL_TEXTURE1);
glActiveTexture(GL_TEXTURE1);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glBindTexture(GL_TEXTURE_2D, overlay.name);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glTexCoordPointer(2, GL_FLOAT, 0, coordinates);
glEnable(GL_TEXTURE_2D);

GLubyte points = 4;

// Draw the square
glVertexPointer(2, GL_FLOAT, 0, vertices);
glDrawArrays(GL_TRIANGLE_STRIP, 0, points);

// Revert back
glActiveTexture(GL_TEXTURE1);
glDisable(GL_TEXTURE_2D);

glClientActiveTexture(GL_TEXTURE0);
glActiveTexture(GL_TEXTURE0);
glEnable(GL_TEXTURE_2D);

glEnableClientState(GL_COLOR_ARRAY);

结果是: