opengl es 2.0 android c ++ glGetTexImage替代

Question

在Windows上进行测试时，代码按预期工作，但在android glGetTexImage上不存在api，还有另一种方法可以从OpenGL获取所有像素，而无需在创建纹理之前将其缓存？

这是代码：

void Texture::Bind(int unit)
{
    glActiveTexture(GL_TEXTURE0 + unit);
    glBindTexture(GL_TEXTURE_2D, mTextureID);
}

GLubyte* Texture::GetPixels()
{
    Bind();

    int data_size = mWidth * mHeight * 4;

    GLubyte* pixels = new GLubyte[mWidth * mHeight * 4];

    glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);

    return pixels;
}

Answer 1

glGetTexImage在OpenGL ES中不存在。
在OpenGL ES中，您必须将纹理附加到帧缓冲区，并通过以下方式从帧缓冲区中读取颜色平面：glReadPixels

Bind();
int data_size = mWidth * mHeight * 4;
GLubyte* pixels = new GLubyte[mWidth * mHeight * 4];

GLuint textureObj = ...; // the texture object - glGenTextures  

GLuint fbo;
glGenFramebuffers(1, &fbo); 
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureObj, 0);

glReadPixels(0, 0, mWidth, mHeight, GL_RGBA, GL_UNSIGNED_BYTE, pixels);

glBindFramebuffer(GL_FRAMEBUFFER, 0);
glDeleteFramebuffers(1, &fbo);