HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 437

T glTexImage1D If an application wants to store the texture at a certain resolution or in a certain format, it can request the resolution and format with internalformat. The GL will choose an internal representation that closely approximates that requested by internalformat, but it may not match exactly. (The representations specified by GL_LUMINANCE, GL_LUMINANCE_ALPHA, GL_RGB, and GL_RGBA must match exactly. The numeric values 1, 2, 3, and 4 may also be used to specify the preceding representations.) Use the GL_PROXY_TEXTURE_1D target to try out a resolution and format. The implementation will update and recompute its best match for the requested storage resolution and format. To query this state, call glGetTexLevelParameter. If the texture cannot be accommodated, texture state is set to 0. A one-component texture image uses only the red component of the RGBA color extracted from pixels. A two-component image uses the R and A values. A three-component image uses the R, G, and B values. A four-component image uses all of the RGBA components. Notes Texturing has no effect in color index mode. The texture image can be represented by the same data formats as the pixels in a glDrawPixels command, except that GL_STENCIL_INDEX and GL_DEPTH_COMPONENT cannot be used. glPixelStore and glPixelTransfer modes affect texture images in exactly the way they affect glDrawPixels. The format value GL_DEPTH_COMPONENT and internalformat values GL_DEPTH_COMPONENT16_EXT, GL_DEPTH_COMPONENT24_EXT, and GL_DEPTH_COMPONENT32_EXT may only be used if the GL_EXT_shadow extension is supported. GL_PROXY_TEXTURE_1D may only be used if the GL version is 1.1 or greater. Internal formats other than 1, 2, 3, or 4 may only be used if the GL version is 1.1 or greater. In GL version 1.1 or greater, pixels may be a null pointer. In this case texture memory is allocated to accommodate a texture of width width. You can then download subtextures to initialize the texture memory. The image is undefined if the program tries to apply an uninitialized portion of the texture image to a primitive. Errors • GL_INVALID_ENUM is generated if target is not GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D. • GL_INVALID_ENUM is generated if format is not an accepted format constant. Format constants other than GL_STENCIL_INDEX and GL_DEPTH_COMPONENT are accepted. • GL_INVALID_ENUM is generated if type is not a type constant. • GL_INVALID_ENUM is generated if type is GL_BITMAP and format is not GL_COLOR_INDEX. • GL_INVALID_VALUE is generated if level is less than 0. Chapter 18 437