Gambas Documentation
Application Repository
Code Snippets
Compilation & Installation
Components
gb
gb.args
gb.cairo
gb.chart
gb.clipper
gb.complex
gb.compress
gb.crypt
gb.data
gb.db
gb.db.form
gb.db.mysql
gb.db.odbc
gb.db.postgresql
gb.db.sqlite2
gb.db.sqlite3
gb.dbus
gb.dbus.trayicon
gb.debug
gb.desktop
gb.desktop.gnome.keyring
gb.desktop.x11
gb.eval
gb.eval.highlight
gb.form
gb.form.dialog
gb.form.editor
gb.form.htmlview
gb.form.mdi
gb.form.print
gb.form.stock
gb.form.terminal
gb.gmp
gb.gsl
gb.gtk
gb.gtk.opengl
gb.gtk3
gb.gtk3.opengl
gb.gtk3.webview
gb.gui
gb.gui.opengl
gb.gui.qt
gb.gui.qt.ext
gb.gui.qt.opengl
gb.gui.qt.webkit
gb.gui.trayicon
gb.gui.webview
gb.hash
gb.highlight
gb.image
gb.image.effect
gb.image.imlib
gb.image.io
gb.inotify
gb.jit
gb.libxml
gb.logging
gb.map
gb.markdown
gb.media
gb.media.form
gb.memcached
gb.mime
gb.mysql
gb.ncurses
gb.net
gb.net.curl
gb.net.pop3
gb.net.smtp
gb.openal
gb.opengl
gb.opengl.glsl
gb.opengl.glu
Glu
AUTO_LOAD_MATRIX
BeginCurve
BeginSurface
BeginTrim
Build1DMipmaps
Build2DMipmaps
ClearColor
Color
CULLING
Cylinder
DeleteNurbsRenderer
Disk
DISPLAY_MODE
EndCurve
EndSurface
EndTrim
ErrorString
FILL
FLAT
INSIDE
INVALID_ENUM
INVALID_VALUE
LINE
LookAt
NewNurbsRenderer
NewQuadric
NONE
NURBS_MODE
NurbsCurve
NurbsProperty
NurbsSurface
Ortho2D
OUT_OF_MEMORY
OUTSIDE
PARAMETRIC_TOLERANCE
PartialDisk
Perspective
PickMatrix
POINT
Project
QuadricDrawStyle
QuadricNormals
QuadricOrientation
QuadricTexture
SAMPLING_METHOD
SAMPLING_TOLERANCE
SILHOUETTE
SMOOTH
Sphere
U_STEP
UnProject
UnProject4
V_STEP
GluNurb
GluQuadric
gb.opengl.sge
gb.openssl
gb.option
gb.pcre
gb.pdf
gb.poppler
gb.qt4
gb.qt4.ext
gb.qt4.opengl
gb.qt4.webkit
gb.qt4.webview
gb.qt5
gb.qt5.ext
gb.qt5.opengl
gb.qt5.webkit
gb.qt5.webview
gb.qt6
gb.qt6.ext
gb.qt6.opengl
gb.qt6.webview
gb.report
gb.report2
gb.scanner
gb.sdl
gb.sdl.sound
gb.sdl2
gb.sdl2.audio
gb.settings
gb.signal
gb.term
gb.test
gb.util
gb.util.web
gb.v4l
gb.vb
gb.web
gb.web.feed
gb.web.form
gb.web.gui
gb.xml
gb.xml.html
gb.xml.rpc
gb.xml.xslt
Controls pictures
Deprecated components
Developer Documentation
Development Environment Documentation
Documents
Error Messages
Gambas Playground
How To's
Language Index
Language Overviews
Last Changes
Lexicon
README
Search the wiki
To Do
Topics
Tutorials
Wiki License
Wiki Manual

Glu.Build2DMipmaps (gb.opengl.glu)

Static Function Build2DMipmaps ( Image As Image ) As Integer

Builds a two-dimensional mipmap.

Parameters

Image

Specifies the Image from which the mipmaps will be generated.
Mismatched markup: </dl> against <dd>

Description

Glu.Build2DMipmaps builds a series of prefiltered two-dimensional texture maps of decreasing resolutions called a mipmap. This is used for the antialiasing of texture-mapped primitives.

A return value of zero indicates success, otherwise a GLU error code is returned (see Glu.ErrorString).

Initially, the width and height of the Image are checked to see if they are a power of 2. If not, a copy of the Image, is scaled up or down to the nearest power of 2. This copy will be used for subsequent mipmapping operations described below. (If width or height of the Image is exactly between powers of 2, then the copy will be scale upwards.)

Then, proxy textures (see Gl.TexImage2D) are used to determine if the implementation can fit the requested texture. If not, both dimensions are continually halved until it fits. (If the OpenGL version is (<= 1.0, both maximum texture dimensions are clamped to the value returned by Gl.GetIntegerv with the argument Glu.MAX_TEXTURE_SIZE.)

Next, a series of mipmap levels is built by decimating a copy of the Image in half along both dimensions until size 1 × 1 is reached. At each level, each texel in the halved mipmap level is an average of the corresponding four texels in the larger mipmap level. (In the case of rectangular images, the decimation will ultimately reach an N × 1 or 1 × N configuration. Here, two texels are averaged instead.)

Gl.TexImage2D is called to load each of these mipmap levels. Level 0 is a copy of data. The highest level is log 2 max width height . For example, if width is 64 and height is 16 and the implementation can store a texture of this size, the following mipmap levels are built: 64 × 16 , 32 × 8 , 16 × 4 , 8 × 2 , 4 × 1 , 2 × 1 , and 1 × 1 These correspond to levels 0 through 6, respectively.

See the Gl.TexImage1D reference page for a description of the acceptable values for format parameter. See the Gl.DrawPixels reference page for a description of the acceptable values for type parameter.

Notes

Note that there is no direct way of querying the maximum level. This can be derived indirectly via Gl.GetTexLevelParameter. First, query for the width and height actually used at level 0. (The width and height may not be equal to width and height respectively since proxy textures might have scaled them to fit the implementation.) Then the maximum level can be derived from the formula log 2 max width height .

Formats Glu.BGR, and Glu.BGRA, and types Glu.UNSIGNED_BYTE_3_3_2, Glu.UNSIGNED_BYTE_2_3_3_REV, Glu.UNSIGNED_SHORT_5_6_5, Glu.UNSIGNED_SHORT_5_6_5_REV, Glu.UNSIGNED_SHORT_4_4_4_4, Glu.UNSIGNED_SHORT_4_4_4_4_REV, Glu.UNSIGNED_SHORT_5_5_5_1, Glu.UNSIGNED_SHORT_1_5_5_5_REV, Glu.UNSIGNED_INT_8_8_8_8, Glu.UNSIGNED_INT_8_8_8_8_REV, Glu.UNSIGNED_INT_10_10_10_2, and Glu.UNSIGNED_INT_2_10_10_10_REV are only available if the GL version is 1.2 or greater and if the GLU version is 1.3 or greater.

Errors

Glu.INVALID_VALUE is returned if width or height is < 1.

Glu.INVALID_ENUM is returned if internalFormat, format, or type is not legal.

Glu.INVALID_OPERATION is returned if type is Glu.UNSIGNED_BYTE_3_3_2 or Glu.UNSIGNED_BYTE_2_3_3_REV and format is not Glu.RGB.

Glu.INVALID_OPERATION is returned if type is Glu.UNSIGNED_SHORT_5_6_5 or Glu.UNSIGNED_SHORT_5_6_5_REV and format is not Glu.RGB.

Glu.INVALID_OPERATION is returned if type is Glu.UNSIGNED_SHORT_4_4_4_4 or Glu.UNSIGNED_SHORT_4_4_4_4_REV and format is neither Glu.RGBA nor Glu.BGRA.

Glu.INVALID_OPERATION is returned if type is Glu.UNSIGNED_SHORT_5_5_5_1 or Glu.UNSIGNED_SHORT_1_5_5_5_REV and format is neither Glu.RGBA nor Glu.BGRA.

Glu.INVALID_OPERATION is returned if type is Glu.UNSIGNED_INT_8_8_8_8 or Glu.UNSIGNED_INT_8_8_8_8_REV and format is neither Glu.RGBA nor Glu.BGRA.

Glu.INVALID_OPERATION is returned if type is Glu.UNSIGNED_INT_10_10_10_2 or Glu.UNSIGNED_INT_2_10_10_10_REV and format is neither Glu.RGBA nor Glu.BGRA.

See also

Glu.Build1DMipmapLevels, Glu.Build2DMipmapLevels, Glu.Build3DMipmapLevels, Glu.Build3DMipmaps, Glu.ErrorString, Gl.GetTexImage, Gl.GetTexLevelParameter, Gl.TexImage3D

See original documentation on OpenGL website