NAME
SoGLBigImage -
The SoGLBigImage class is used to handle 2D OpenGL textures of any
size.
SYNOPSIS
#include <include/Inventor/misc/SoGLBigImage.h>
Inherits SoGLImage.
Public Member Functions
SoGLBigImage ()
virtual void unref (SoState *state=NULL)
virtual SoType getTypeId (void) const
virtual void setData (const SbImage *image, const Wrap wraps=REPEAT,
const Wrap wrapt=REPEAT, const float quality=0.5f, const int
border=0, SoState *createinstate=NULL)
virtual void setData (const SbImage *image, const Wrap wraps, const
Wrap wrapt, const Wrap wrapr, const float quality=0.5f, const int
border=0, SoState *createinstate=NULL)
int initSubImages (const SbVec2s &subimagesize) const
void handleSubImage (const int idx, SbVec2f &start, SbVec2f &end,
SbVec2f &tcmul)
void applySubImage (SoState *state, const int idx, const float quality,
const SbVec2s &projsize)
SbBool exceededChangeLimit (void)
virtual SoGLDisplayList * getGLDisplayList (SoState *state)
Static Public Member Functions
static SoType getClassTypeId (void)
static int setChangeLimit (const int limit)
static void initClass (void)
Protected Member Functions
virtual void unrefOldDL (SoState *state, const uint32_t maxage)
Detailed Description
The SoGLBigImage class is used to handle 2D OpenGL textures of any
size.
This class is internal. To enable/disable big-image texture handling
you should use the SoTextureScalePolicy node.
The technique used is the following: split the texture into x*y equal
size blocks. All these subtextures are of size 2^n, and are typically
quite small (256x256 or smaller). Each triangle is clipped, based on
the texture coordinates, into several smaller triangles. The triangles
will then be guaranteed to use only one subtexture. Then the triangles
are projected onto the screen, and the maximum projected size for each
subtexture is calculated. Subtextures outside the viewport will be
culled. Each subtexture is then sampled down to a 2^n value close to
the projected size, and a GL texture is created with this size. This GL
texture is used when rendering triangles that are clipped into that
subtexture.
Mipmapping is disabled for SoGLBigImage. Aliasing problems shouldn’t
occur because the projected size of the texture is calculated on the
fly. When mipmapping is enabled, the amount of texture memory used is
doubled, and creating the texture object is much slower, so we avoid
this for SoGLBigImage.
Be aware that this class is an extension for Coin, and it is not
available in the original SGI Open Inventor v2.1 API.
Since:
Coin 2.0
Constructor & Destructor Documentation
SoGLBigImage::SoGLBigImage (void) Constructor.
Member Function Documentation
void SoGLBigImage::unref (SoState * state = NULL) [virtual] This class has
a private destuctor since we want users to supply the current GL state
when deleting the image. This is to make sure gl texture objects are
freed as soon as possible. If you supply NULL to this method, the gl
texture objects won’t be deleted until the next time an GLRenderAction
is applied in the image’s cache context(s).
Reimplemented from SoGLImage.
SoType SoGLBigImage::getClassTypeId (void) [static] Returns the type id for
this class.
Reimplemented from SoGLImage.
SoType SoGLBigImage::getTypeId (void) const [virtual] Returns the type id
for an SoGLImage instance.
Reimplemented from SoGLImage.
void SoGLBigImage::setData (const SbImage * image, const Wrap wraps =
REPEAT, const Wrap wrapt = REPEAT, const float quality = 0.5f, const
int border = 0, SoState * createinstate = NULL) [virtual] Convenience
2D wrapper function around the 3D setData().
Reimplemented from SoGLImage.
void SoGLBigImage::setData (const SbImage * image, const Wrap wraps, const
Wrap wrapt, const Wrap wrapr, const float quality = 0.5f, const int
border = 0, SoState * createinstate = NULL) [virtual] Sets the data for
this GL image. Should only be called when one of the parameters have
changed, since this will cause the GL texture object to be recreated.
Caller is responsible for sending legal Wrap values. CLAMP_TO_EDGE is
only supported on OpenGL v1.2 implementations, and as an extension on
some earlier SGI implementations (GL_SGIS_texture_edge_clamp).
For now, if quality > 0.5 when created, we create mipmaps, otherwise a
regular texture is created. Be aware, if you for instance create a
texture with texture quality 0.4, and then later try to apply the
texture with a texture quality greater than 0.5, the texture object
will be recreated as a mipmap texture object. This will happen only
once though, of course.
If border != 0, the OpenGL texture will be created with this border
size. Be aware that this might be extremely slow on most PC hardware.
Normally, the OpenGL texture object isn’t created until the first time
it is needed, but if createinstate is != NULL, the texture object is
created immediately. This is useful if you use a temporary buffer to
hold the texture data. Be careful when using this feature, since the
texture data might be needed at a later stage (for instance to create a
texture object for another context). It will not be possible to create
texture objects for other cache contexts when createinstate is != NULL.
Also if createinstate is supplied, and all the attributes are the same
as the current data in the image, glTexSubImage() will be used to
insert the image data instead of creating a new texture object. This is
much faster on most OpenGL drivers, and is very useful, for instance
when doing animated textures.
If you supply NULL for image, the instance will be reset, causing all
display lists and memory to be freed.
Reimplemented from SoGLImage.
SbBool SoGLBigImage::exceededChangeLimit (void) To avoid doing too much
work in one frame, there is a limit on the number of subtextures that
can be changed each frame. If this limit is exceeded, this function
will return TRUE, otherwise FALSE.
See also:
setChangeLimit()
int SoGLBigImage::setChangeLimit (const int limit) [static] Sets the change
limit. Returns the old limit.
See also:
exceededChangeLimit()
Since:
Coin 2.3
SoGLDisplayList * SoGLBigImage::getGLDisplayList (SoState * state)
[virtual] Returns or creates a SoGLDisplayList to be used for
rendering. Returns NULL if no SoDLDisplayList could be created.
Reimplemented from SoGLImage.
void SoGLBigImage::unrefOldDL (SoState * state, const uint32_t maxage)
[protected, virtual] Virtual method that will be called once each
frame. The method should unref display lists that has an age bigger or
equal to maxage, and increment the age for other display lists.
Reimplemented from SoGLImage.
void SoGLBigImage::initClass (void) [static] This API member is considered
internal to the library, as it is not likely to be of interest to the
application programmer.
Reimplemented from SoGLImage.
Author
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