fglGetTexImage(3G)
fglGetTexImage - return a texture image
As shipped in IRIX 6.5.19. Last changed in IRIX 6.5.15.
NAME fglGetTexImage - return a texture image FORTRAN SPECIFICATION SUBROUTINE fglGetTexImage( INTEGER*4 target, INTEGER*4 level, INTEGER*4 format, INTEGER*4 type, CHARACTER*8 pixels ) PARAMETERS target Specifies which texture is to be obtained. GL_TEXTURE_1D, GL_TEXTURE_2D, GL_DETAIL_TEXTURE_2D_SGIS, and GL_TEXTURE_3D are accepted. level 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. format Specifies a pixel format for the returned data. The supported formats are GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_BGR, GL_RGBA, GL_BGRA, GL_ABGR_EXT, GL_LUMINANCE, and GL_LUMINANCE_ALPHA. type 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, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, and GL_UNSIGNED_INT_2_10_10_10_REV. pixels Returns the texture image. Should be a pointer to an array of the type specified by type. DESCRIPTION fglGetTexImage returns a texture image into pixels. target specifies whether the desired texture image is one specified by fglTexImage1D (GL_TEXTURE_1D), fglTexImage2D (GL_TEXTURE_2D or GL_DETAIL_TEXTURE_2D_SGIS), or fglTexImage3D (GL_TEXTURE_3D). 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 fglTexImage1D and fglDrawPixels for a description of the acceptable values for the format and type parameters, respectively. To understand the operation of fglGetTexImage, consider the selected internal four-component texture image to be an RGBA color buffer the size of the image. The semantics of fglGetTexImage are then identical to those of fglReadPixels, with the exception that no pixel transfer operations are performed, when 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. (Similar considerations apply to 3D images, though there is no direct analogy with fglReadPixels.) 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. If the selected texture image does not contain four components, the following mappings are applied. Single-component textures are treated as RGBA buffers with red set to the single-component value, green set to 0, blue set to 0, and alpha set to 1. Two-component textures are treated as RGBA buffers with red set to the value of component zero, alpha set to the value of component one, and green and blue set to 0. Finally, three-component textures are treated as RGBA buffers with red set to component zero, green set to component one, blue set to component two, and alpha set to 1. To determine the required size of pixels, use fglGetTexLevelParameter to determine the dimensions of the internal texture image, then scale the required number of pixels by the storage required for each pixel, based on format and type. Be sure to take the pixel storage parameters into account, especially GL_PACK_ALIGNMENT. NOTES If an error is generated, no change is made to the contents of pixels. If type is set to GL_UNSIGNED_BYTE_3_3_2_EXT, GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT, GL_UNSIGNED_INT_8_8_8_8_EXT, or GL_UNSIGNED_INT_10_10_10_2_EXT and the EXT_packed_pixels extension is not supported then a GL_INVALID_ENUM error is generated. GL_ABGR_EXT is part of the EXT_abgr extension and GL_DETAIL_TEXTURE_2D_SGIS is part of the SGIS_detail_texture extension. The types GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, GL_UNSIGNED_INT_2_10_10_10_REV, and the formats GL_BGR, and GL_BGRA are available only if the GL version is 1.2 or greater. ERRORS GL_INVALID_ENUM is generated if target, format, or type is not an accepted value. GL_INVALID_VALUE is generated if level is less than 0. GL_INVALID_VALUE may be generated if level is greater than log max, where 2 max is the returned value of GL_MAX_TEXTURE_SIZE. GL_INVALID_OPERATION is generated if fglGetTexImage is executed between the execution of fglBegin and the corresponding execution of fglEnd. GL_INVALID_OPERATION is returned if type is one of GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5, or GL_UNSIGNED_SHORT_5_6_5_REV and format is not GL_RGB. GL_INVALID_OPERATION is returned if type is one of GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, or GL_UNSIGNED_INT_2_10_10_10_REV, and format is not GL_RGBA, GL_BGRA or GL_ABGR_EXT. GL_INVALID_OPERATION is generated when the SGIX_subsample extension is supported, and the pixel storage mode GL_PACK_SUBSAMPLE_RATE_SGIX is not GL_PIXEL_SUBSAMPLE_4444_SGIX, and the width of the texture image is not a multiple of 2, or format is not a 3 or 4 component format, or type is a packed pixels type. ASSOCIATED GETS fglGetTexLevelParameter with argument GL_TEXTURE_WIDTH fglGetTexLevelParameter with argument GL_TEXTURE_HEIGHT fglGetTexLevelParameter with argument GL_TEXTURE_DEPTH_EXT fglGetTexLevelParameter with argument GL_TEXTURE_BORDER fglGetTexLevelParameter with argument GL_TEXTURE_INTERNALFORMAT fglGet with arguments GL_PACK_ALIGNMENT and others MACHINE DEPENDENCIES RealityEngine, RealityEngine2, and VTX systems do not support color matrix transformations on images as they are loaded to or read back from texture memory. RealityEngine, RealityEngine2, and VTX systems do not support convolving texture images as they are retrieved from texture memory. The EXT_packed_pixels extension is not supported on RealityEngine, RealityEngine2, and VTX systems. The SGIX_subsample and SGIX_resample extensions are supported only on Octane2 VPro systems. Applying the GL_PIXEL_SUBSAMPLE_2424_SGIX subsample rate is accelerated for direct immmediate mode transfers when the format is GL_RGB or GL_RGBA, and the type is GL_UNSIGNED_BYTE or GL_UNSIGNED_SHORT. SEE ALSO fglDrawPixels, fglReadPixels, fglTexEnv, fglTexGen, fglTexImage1D, fglTexImage2D, fglTexImage3D, fglTexSubImage1D, fglTexSubImage2D, fglTexSubImage3D, fglTexParameter