HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 78

C glCopyTexImage2D Description glCopyTexImage2D defines a two-dimensional texture image with pixels from the current GL_READ_BUFFER. The screen-aligned pixel rectangle with lower left corner at (x, y) and with a width of width + 2 × border and a height of height + 2 × border defines the texture array at the mipmap level specified by level. internalFormat specifies the internal format of the texture array. The pixels in the rectangle are processed exactly as if glCopyPixels had been called, but the process stops just before final conversion. At this point all pixel component values are clamped to the range [0, 1] and then converted to the texture's internal format for storage in the texel array. Pixel ordering is such that lower x and y screen coordinates correspond to lower s and t texture coordinates. If any of the pixels within the specified rectangle of the current GL_READ_BUFFER are outside the window associated with the current rendering context, then the values obtained for those pixels are undefined. Notes glCopyTexImage2D is available only if the GL version is 1.1 or greater. Texturing has no effect in color index mode. 1, 2, 3, and 4 are not accepted values for internalFormat. The GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT16_EXT, GL_DEPTH_COMPONENT24_EXT, and GL_DEPTH_COMPONENT32_EXT values of internalFormat may be used. An image with height or width of 0 indicates a NULL texture. Errors • GL_INVALID_ENUM is generated if target is not GL_TEXTURE_2D. • GL_INVALID_VALUE is generated if level is less than 0. • GL_INVALID_VALUE may be generated if level is greater than log2 max, where max is the returned value of GL_MAX_TEXTURE_SIZE. • GL_INVALID_VALUE is generated if width or height is less than 0, greater than 2 + GL_MAX_TEXTURE_SIZE, or if width or height cannot be represented as 2k + 2 × border for some integer k. • GL_INVALID_VALUE is generated if border is not 0 or 1. • GL_INVALID_VALUE is generated if internalFormat is not one of the allowable values. • GL_INVALID_OPERATION is generated if glCopyTexImage2D is executed between the execution of glBegin and the corresponding execution of glEnd. 78 Chapter 3