HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 217

Chapter 7 G glGetTexImage glGetTexImage glGetTexImage: return a texture image. C Specification void glGetTexImage( GLenum target, GLint level, GLenum format, GLenum type, GLvoid *pixels) Parameters target level format type pixels Specifies which texture is to be obtained. GL_TEXTURE_1D and GL_TEXTURE_2D are accepted. Specifies the level-of-detail number of the desired image. Level 0 is the base image level. Level n is the nth mipmap reduction image. Specifies a pixel format for the returned data. The supported formats are GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA. Specifies a pixel type for the returned data. The supported types are GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT, and GL_FLOAT. Returns the texture image. Should be a pointer to an array of the type specified by type. Description glGetTexImage returns a texture image into pixels. target specifies whether the desired texture image is one specified by glTexImage1D (GL_TEXTURE_1D) or by glTexImage2D (GL_TEXTURE_2D). level specifies the level-of-detail number of the desired image. format and type specify the format and type of the desired image array. See the reference pages glTexImage1D and glDrawPixels for a description of the acceptable values for the format and type parameters, respectively. To understand the operation of glGetTexImage, consider the selected internal four-component texture image to be an RGBA color buffer the size of the image. The semantics of glGetTexImage are then identical to those of glReadPixels called with the same format and type, with x and y set to 0, width set to the width of the texture image (including border if one was specified), and height set to 1 for 1D images, or to the height of the texture image (including border if one was specified) for 2D images. Because the internal texture image is an RGBA image, pixel formats GL_COLOR_INDEX, GL_STENCIL_INDEX, and GL_DEPTH_COMPONENT are not accepted, and pixel type GL_BITMAP is not accepted. 217