如何在iOS的SceneKit中的OpenGL SL着色器中使用多个纹理？

Question

我有一个包含以下两个变量的文件：

uniform highp sampler2D textureImage1;
uniform highp sampler2D textureImage2;

在我的代码中，我使用以下方法将图像绑定到这些图像：

[myNode.geometry.firstMaterial handleBindingOfSymbol:@"textureImage1" usingBlock:^(unsigned int programID, unsigned int location, SCNNode *renderedNode, SCNRenderer *renderer) {
    glBindTexture(GL_TEXTURE_2D, texture1.name);
}];

[myNode.geometry.firstMaterial handleBindingOfSymbol:@"textureImage2" usingBlock:^(unsigned int programID, unsigned int location, SCNNode *renderedNode, SCNRenderer *renderer) {
    glBindTexture(GL_TEXTURE_2D, texture2.name);
}];

奇怪的是，这两个纹理都出现了第一张图像。

每个碎片文件只能使用一种纹理吗？

这是iOS 8。

Answer 1

如果我这样做，它将起作用：

[myNode.geometry.firstMaterial handleBindingOfSymbol:@"textureImage1" usingBlock:^(unsigned int programID, unsigned int location, SCNNode *renderedNode, SCNRenderer *renderer) {
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture1.name);
    glUniform1i(location, 0);
}];

[myNode.geometry.firstMaterial handleBindingOfSymbol:@"textureImage2" usingBlock:^(unsigned int programID, unsigned int location, SCNNode *renderedNode, SCNRenderer *renderer) {
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, texture2.name);
    glUniform1i(location, 1);
}];