Parameters

Description

glGenerateMipmap generates mipmaps for the texture attached to target of the active texture unit. For cube map textures, a GL_INVALID_OPERATION error is generated if the texture attached to target is not cube complete.

Mipmap generation replaces texel array levels ${\mathit{level}}_{\mathrm{base}}+1$ through $\mathit{q}$ with arrays derived from the ${\mathit{level}}_{\mathrm{base}}$ array, regardless of their previous contents. All other mimap arrays, including the ${\mathit{level}}_{\mathrm{base}}$ array, are left unchanged by this computation.

The internal formats of the derived mipmap arrays all match those of the ${\mathit{level}}_{\mathrm{base}}$ array. The contents of the derived arrays are computed by repeated, filtered reduction of the ${\mathit{level}}_{\mathrm{base}}$ array. For two-dimensional texture arrays, each layer is filtered independently.

Errors

GL_INVALID_ENUM is generated if target is not one of the accepted texture targets.

GL_INVALID_OPERATION is generated if target is GL_TEXTURE_CUBE_MAP and the texture bound to the GL_TEXTURE_CUBE_MAP target of the active texture unit is not cube complete.

GL_INVALID_OPERATION is generated if the ${\mathit{level}}_{\mathrm{base}}$ array is stored in a compressed internal format.

GL_INVALID_OPERATION is generated if the ${\mathit{level}}_{\mathrm{base}}$ array was not specified with an unsized internal format or a sized internal format that is both color-renderable and texture-filterable.

Examples

GLuint texture_id;
glGenTextures(1, &texture_id);
glBindTexture(GL_TEXTURE_2D, texture_id);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

// texture_data is the source data of your texture, in this case
// its size is sizeof(unsigned char) * texture_width * texture_height * 4
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texture_width, texture_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, texture_data);
glGenerateMipmap(GL_TEXTURE_2D); // Unavailable in OpenGL 2.1, use gluBuild2DMipmaps() instead

glBindTexture(GL_TEXTURE_2D, 0);

Tutorials

Songho - OpenGL Frame Buffer Object (FBO)
open.gl - Textures Objects and Parameters
opengl-tutorial.org - Tutorial 5 : A Textured Cube

API Version Support

See Also

glTexImage2D, glBindTexture, glGenTextures

Copyright

Copyright © 2010-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. https://opencontent.org/openpub/.