glTexSubImage2DEXT(3G)
glTexSubImage2DEXT - specify a two-dimensional texture subimage
As shipped in IRIX 6.5. First release of IRIX 6.5.
NAME glTexSubImage2DEXT - specify a two-dimensional texture subimage C SPECIFICATION void glTexSubImage2DEXT( GLenum target, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid *pixels ) PARAMETERS target Specifies the target texture. Must be GL_TEXTURE_2D or GL_DETAIL_TEXTURE_2D_SGIS. level Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image. xoffset Specifies a texel offset in the x direction within the texture array. yoffset Specifies a texel offset in the y direction within the texture array. width Specifies the width of the texture subimage. height Specifies the height of the texture subimage. format Specifies the format of the pixel data. The following symbolic values are accepted: GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA, GL_ABGR_EXT, GL_LUMINANCE, GL_LUMINANCE_ALPHA, and GL_DEPTH_COMPONENT. type Specifies the data type of the pixel data. The following symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT, GL_FLOAT, 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, and GL_UNSIGNED_INT_10_10_10_2_EXT. pixels Specifies a pointer to the image data in memory. DESCRIPTION Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is enabled. Two-dimensional texturing is enabled and disabled using glEnable and glDisable with argument GL_TEXTURE_2D. glTexSubImage2DEXT redefines a contiguous subregion of an existing two- dimensional texture image. The texels referenced by pixels replace the portion of the existing texture array with x indices xoffset and xoffset+width-1, inclusive, and y indices yoffset and yoffset+height-1, inclusive (But, see discussion of GL_INTERLACE_SGIX below). This region may not include any texels outside the range of 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. When GL_INTERLACE_SGIX is disabled, then counting from zero, each Nth texel from pixels is assigned to texture array indices [i,j], where i = xoffset+(N mod width) and j = yoffset+((N div width) mod height). If GL_INTERLACE_SGIX is enabled, then every other row of the destination texture is skipped. That is, the destination row for texel N is yoffset+2((N div width) mod height). A complete video frame may be assembled in texture memory by invoking glTexSubImage2DEXT on two consecutive video fields, with yoffset values that differ by one. NOTES Texturing has no effect in color index mode. glPixelStore and glPixelTransfer modes affect texture images in exactly the way they affect glDrawPixels. glTexSubImage2DEXT is part of the EXT_subtexture extension. 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. See glIntro for more information on using extensions. ERRORS GL_INVALID_ENUM is generated when target is not one of the allowable values. GL_INVALID_OPERATION is generated when the texture array has not been defined by a previous glTexImage2D operation. 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 width < -TEXTURE_BORDER or if height < -TEXTURE_BORDER, where TEXTURE_BORDER is the border width of the texture array. 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_ENUM is generated when format is not an accepted format constant. GL_INVALID_ENUM is generated when 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_OPERATION is generated if glTexSubImage2DEXT is executed between the execution of glBegin and the corresponding execution of glEnd. ASSOCIATED GETS glGetTexImage glIsEnabled with argument GL_TEXTURE_2D 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 images as they are loaded into texture memory. 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. RealityEngine, RealityEngine2, and VTX systems do not support histogram or minmax operations on images as they are being loaded into texture memory. The SGIX_interlace extension is supported only on InfiniteReality systems, on RealityEngine, RealityEngine2, and VTX systems, and on O2 systems. The EXT_packed_pixels extension is not supported on RealityEngine, RealityEngine2, and VTX systems. On RealityEngine, RealityEngine2, and VTX systems, glTexSubImage2D and glTexSubImage2DEXT are supported with the following restrictions: 1. Performance is significantly better if the texture subimage X offset, Y offset, width and height are multiples of 32. 2. glTexSubImage2D and glTexSubImage2DEXT may be used only with a texture that was created using glTexImage2D with a NULL texture image. 3. glTexSubImage2D and glTexSubImage2DEXT may not be used with a mipmap texture. Only level 0 is supported. 4. Only the following texel format and type combinations are supported: GL_LUMINANCE and GL_UNSIGNED_BYTE, GL_LUMINANCE and GL_UNSIGNED_SHORT, GL_LUMINANCE_ALPHA and GL_UNSIGNED_BYTE, GL_LUMINANCE_ALPHA and GL_UNSIGNED_SHORT, GL_RGB and GL_UNSIGNED_BYTE and GL_RGBA and GL_UNSIGNED_BYTE. Any other combination of format and type will result in a GL_INVALID_ENUM error. 5. Using glTexSubImage2D or glTexSubImage2DEXT in conjunction with pixel mapping results in a GL_INVALID_OPERATION error (see glPixelTransfer and glPixelMap). 6. glTexSubImage2D and glTexSubImage2DEXT may not be used in display lists or when rendering remotely. 7. GL_INTERLACE_SGIX is not supported (see glEnable). 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. SEE ALSO glDrawPixels, glFog, glPixelStore, glPixelTransfer, glTexEnv, glTexGen, glTexImage2D, glTexParameter.