glCopyTexSubImage2DEXT(3G)
glCopyTexSubImage2DEXT - copy pixels into a 2D texture subimage
As shipped in IRIX 6.5.22. Last changed in IRIX 6.5.15.
NAME glCopyTexSubImage2DEXT - copy pixels into a 2D texture subimage C SPECIFICATION void glCopyTexSubImage2DEXT( GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint x, GLint y, GLsizei width, GLsizei height ) PARAMETERS target The target texture. Must be GL_TEXTURE_2D or GL_DETAIL_TEXTURE_2D_SGIS. level The level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image. xoffset A texel offset in the x direction within the texture array. yoffset A texel offset in the y direction within the texture array. x The x coordinate of the lower-left corner of the pixel rectangle to be transferred to the texture array. y The y coordinate of the lower-left corner of the pixel rectangle to be transferred to the texture array. width The width of the texture subimage. height The height of the texture subimage. DESCRIPTION glCopyTexSubImage2DEXT replaces a rectangular portion of a two- dimensional texture image with pixels from the current GL_READ_BUFFER (rather than from main memory, as is the case for glTexSubImage2DEXT). The screen-aligned pixel rectangle with lower-left corner at (x, y) having width width and height height replaces the portion of the texture array with x indices xoffset through xoffset+width-1, inclusive, and y indices yoffset through yoffset+height-1, inclusive, at the mipmap level specified by level. (But see the paragraph about GL_INTERLACE_SGIX below). 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. The destination rectangle in the texture array may not include any texels outside the texture array as it was originally specified. It is not an error to specify a subtexture with zero width or height, but such a specification has no effect. If any of the pixels within the specified rectangle of the current GL_READ_BUFFER are outside the read window associated with the current rendering context, then the values obtained for those pixels are undefined. When GL_INTERLACE_READ_INGR is enabled, every other row of the source pixel rectangle is read. The height of the source pixel rectangle is equivalent to 2xheight. Only rows (y+0,y+2,...) of the source are used to define the rows of the texture subimage that are affected by the copy. When GL_INTERLACE_SGIX is enabled, source pixels are written to every other row in the texture subimage, rather than to every successive row. The height of the subimage is equivalent to 2xheight. Rows (yoffset+0,yoffset+2,...) of the destination texture are affected, while rows (yoffset+1,yoffset+3,...) are not modified. A complete video frame may be assembled in texture memory by invoking glCopyTexSubImage2DEXT on two consecutive video fields, with yoffset values that differ by one. NOTES glCopyTexSubImage2DEXT is part of the EXT_copy_texture extension, GL_INTERLACE_SGIX is part of the SGIX_interlace extension, and GL_INTERLACE_READ_INGR is part of the INGR_interlace_read extension. See glIntro for more information about using extensions. ERRORS GL_INVALID_ENUM is generated when target is not one of the allowable values. GL_INVALID_VALUE is generated if level is less than zero or greater than log (max), where max is the returned value of GL_MAX_TEXTURE_SIZE. 2 GL_INVALID_VALUE is generated if xoffset<-TEXTURE_BORDER, (xoffset+width)>(TEXTURE_WIDTH-TEXTURE_BORDER), yoffset<-TEXTURE_BORDER, or (yoffset+interlacexheight)>(TEXTURE_HEIGHT-TEXTURE_BORDER). Where TEXTURE_WIDTH, TEXTURE_HEIGHT, and TEXTURE_BORDER are the state values of the texture image being modified, and interlace is 1 if GL_INTERLACE_SGIX is disabled and 2 otherwise. Note that TEXTURE_WIDTH and TEXTURE_HEIGHT include twice the border width. GL_INVALID_VALUE is generated if width or height is negative. GL_INVALID_OPERATION is generated when the texture array has not been defined by a previous glTexImage2D (or equivalent) operation. GL_INVALID_OPERATION is generated if glCopyTexSubImage2DEXT is executed between the execution of glBegin and the corresponding execution of glEnd. ASSOCIATED GETS glGetTexImage 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 support glCopyTexSubImage2D and glCopyTexSubImage2DEXT with the following restrictions: 1. Only level 0 is supported; other levels result in a GL_INVALID_VALUE error. 2. The texel offsets and the dimensions of the subimage must be multiples of 32; otherwise a GL_INVALID_VALUE error is generated. 3. If glCopyTexSubImage2D or glCopyTexSubImage2DEXT is used when a GLX video source is the read drawable (see glXMakeCurrentReadSGI), the X offset and Y offset must both be 0 and the subimage width must be 768; otherwise a GL_INVALID_VALUE error is generated. 4. GL_INTERLACE_SGIX is not supported (see glEnable). On InfiniteReality systems, there is a performance benefit when the width of the image to be transferred to texture memory is a multiple of 8. Texture borders are not supported on InfiniteReality systems. Applications should use borderless textures and GL_CLAMP_TO_EDGE_SGIS wrap mode. On High Impact and Maximum Impact systems, if the right side of the image to be transferred to texture memory is not the right side of the texture, then its index must be a multiple of 32, where index = xoffset+width. Otherwise it will generate a GL_INVALID_VALUE error. The SGIX_interlace extension is supported only on InfiniteReality systems, on RealityEngine, RealityEngine2, and VTX systems, on Octane2 VPro systems, and on O2 systems. The INGR_interlace_read extension is supported only on Octane2 VPro systems, and on O2 systems. On O2 systems, when the current read drawable is a DM pbuffer, using glCopyTexSubImage2D or glCopyTexSubImage2DEXT to copy into a full texture image whose dimensions and format match those of the pbuffer causes a copy-by-reference. This has performance advantages, especially for video-generated DMbuffers, because it provides a DMA path for updating textures. Following the copy, rendering to the pbuffer or otherwise modifying the DMbuffer, will directly affect texture memory. However, this behavior is essentially an unspecified side-effect of the implementation on O2, and cannot be used on other systems. SEE ALSO glTexImage2D, glTexSubImage2DEXT, glCopyPixels.