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glGenerateMipmap

Name

glGenerateMipmap — generate mipmaps for a specified texture target

C Specification

void glGenerateMipmap( GLenum target);
 

Parameters

target

Specifies the target to which the texture whose mimaps to generate is bound. target must be GL_TEXTURE_2D, GL_TEXTURE_3D, GL_TEXTURE_2D_ARRAY or GL_TEXTURE_CUBE_MAP.

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 level base + 1 through q with arrays derived from the level base array, regardless of their previous contents. All other mimap arrays, including the level base array, are left unchanged by this computation.

The internal formats of the derived mipmap arrays all match those of the level base array. The contents of the derived arrays are computed by repeated, filtered reduction of the level 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 level base array is stored in a compressed internal format.

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

Examples

Create a texture object with linear mipmaps and edge clamping.
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() insteads.

glBindTexture(GL_TEXTURE_2D, 0);

API Version Support

OpenGL ES API Version
Function Name 2.0 3.0 3.1
glGenerateMipmap
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