glTexSubImage2D

Name

glTexSubImage2D - specify a two-dimensional texture subimage

C Specification

void glTexSubImage2D(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.
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 of the pixel data. The following symbolic values are accepted: GL_ALPHA, GL_RGB, GL_RGBA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA.
type: Specifies the data type of the pixel data. The following symbolic values are accepted: GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_4_4_4_4, and GL_UNSIGNED_SHORT_5_5_5_1.
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. To enable and disable two-dimensional texturing, call glEnable and glDisable with argument GL_TEXTURE_2D. Two-dimensional texturing is initially disabled.

glTexSubImage2D 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. 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.

Notes

glPixelStore affects texture images in exactly the way it affects glTexImage2D.

glTexSubImage2D specifies a two-dimensional sub texture for the currently bound texture, specified with glBindTexture and current texture unit, specified with glActiveTexture.

Errors

GL_INVALID_ENUM is generated if target is not GL_TEXTURE_2D.

GL_INVALID_OPERATION is generated if the texture array has not been defined by a previous glTexImage2D or glCopyTexImage2D operation.

GL_INVALID_VALUE is generated if level is less than 0.

GL_INVALID_VALUE may be generated if level is greater than log₂max, where max is the returned value of GL_MAX_TEXTURE_SIZE.

GL_INVALID_VALUE is generated if xoffset < - b, xoffset + width > (w - b) , yoffset < - b, or yoffset + height > (h - b) , where w is the texture width, h is the texture height, and b is the border of the texture image being modified. Note that w and h include twice the border width.

GL_INVALID_VALUE is generated if width or height is less than 0.

GL_INVALID_ENUM is generated if format is not an accepted constant.

GL_INVALID_ENUM is generated if type is not a type constant.

GL_INVALID_OPERATION is generated if type is GL_UNSIGNED_SHORT_5_6_5 and format is not GL_RGB.

GL_INVALID_OPERATION is generated if type is one of GL_UNSIGNED_SHORT_4_4_4_4, or GL_UNSIGNED_SHORT_5_5_5_1 and format is not GL_RGBA.

Associated Gets

glGet with argument GL_MAX_TEXTURE_SIZE

Copyright

This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.