performance option, I added a flag to control whether the depth writing
pass is performed.
Since text is alpha-blended when rendering, it is placed in the
transparent bin and rendered back to front. Writing to the depth buffer
should therefore be unnecessary. Indeed, rendering something behind text
(or any blended object) after that object is drawn will give incorrect
results whether the depth buffer is written or not. I therefore think it
is safe to keep this option off by default. Users can turn it on for any
special needs they have.
I did not fix the existing backdrop implementations to work with the new
code since this new method of rendering intrinsically handles backdrops
correctly. Its results are more accurate than all of the existing
backdrop implementations. Its only downside is that it requires two
passes if depth buffer updates are desired, whereas DEPTH_RANGE and
POLYGON_OFFSET achieve their (less accurate) results in one pass. The
NO_DEPTH_BUFFER method also only uses one pass, but it disables depth
tests and not depth writes so will have serious problems if anything is
drawn in front of the text before OR after the text is drawn.
Given the better all-around behavior of the new method, I believe the
other backdrop implementations can be safely removed. Code that adjusts
the backdrop implementation will of course be broken if the member
functions are removed. For this reason I left them in, but set the new
rendering method as the default backdrop implementation. At the very
least I think the old backdrop implementations should be deprecated and
removed at a later date.
"
Note from Robert Osfield, testing this submission with osgtext I found that the
text would not render correctly when different text labels were overlapping
in deth and screen space. I change _enableDepthWrites to default to true and
found the that which artifacts still occurred around the alpha blended edges
the artifacts where better than issue with occlusion of nearer pixels that was
happening with _enableDepthWrites set to false.I therefore set the
_enableDepthWrites to true as I feel it's the lesser of the two artefacts.
http://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg33967.html
, interpolating through HSV space gives a rainbow color effect which
does not mimic the simple RGB color interpolation that OpenGL does.
It's overkill and causes unexpected visual artifacts. In the attached
files I've removed the conversion to HSV so that interpolation happens
in RGB space."
behind osgText::Text. I made it so the box would get drawn using
whichever BackdropImplementation was selected. However, I did not
implement STENCIL_BUFFER. In that case it defaults to drawing the
bounding box using POLYGON_OFFSET instead.
Also made it so the BOUNDINGBOX and FILLEDBOUNDINGBOX are drawn with a
settable color and margin size.
While I was at it I tightened up the values applied with DEPTH_RANGE
and POLYGON_OFFSET, not just for drawing the bounding box but also for
drawing backdrop text (these values must be coupled since the bounding
box has to be drawn deeper in Z than the backdrop text). The values
in use before seemed like overkill and I was seeing some z-clipping
with my background scenery in the case of DEPTH_RANGE. If there was a
good reason for the large values please let me know...."
osgText::Text and osgText::Text3D use the same font file.
The first really load the file and obtain an osgText::Font object,
the second use the cache created during the first load of the
font file, and so obtain an osgText::Font object instead of
osgText::Font3D object. To obtain an osgText::Font3D object,
osgText::Text3D call osgDB::readObjectFile(...) with an option
to specify the plugin we want an osgText::Font3D instead of
osgText::Font.
Generalised Problem:
In osgDB::Registry, loaded file cache is referenced by the name
of this file, so if I load a file with some options, and the cache
already contain object for this filename, I obtain an object
potentially not loaded with my options.
Behaviours:
Cache management is delegate to osgDB::Registry, but cache
coherence (load a file with option then reuse it, deactivate the
cache when load a specific file or don't cached the loaded file)
is user's responsibility.
Text3D solution:
Postfix the font file name by .text3d or something similar and then have the freetype plugin return
osgText::Font3D when it detects this.
This operation is done by osgText::readFont3DFile() which unsure the filename have .text3d as extension.
This is totaly transparent for user, and backward compatible.
BTW, I fix the bug about the Normal of 3D text. Currently, the front and wall face have
the same normal (0,0,1) in the Text3D object coordinate. Now the wall face have its own
normal array computed by the plugin.
BTW 2, I implement
- void Text3D::accept(osg::Drawable::ConstAttributeFunctor& af) const
- void Text3D::accept(osg::PrimitiveFunctor& pf) const
so now statistics are well reported.
"
attached code adds this, along with a member variable to keep track of
the setting. It is based on the latest subversion version, and was
tested by creating a new text object with the same axis alignment as an
existing one (e.g.
new_text->setAxisAlignment(old_text->getAxisAlignment()); )."
From Robert Osfield, " I originally didn't add a getAxisAlignment()
as all setAxisAlignment does is set the Rotation member variable, and
potentially one could apply user defined Rotation setting after the
setAxisAlignment() which would bring it out of sync with the
setAxisAlignment.
Rather than reject your submission on the ground of potentially
getting out of sync and therefore misleading users I've added a
USED_DEFINED_ROTATION to AxisAlignment enum, and set this in the
serRotation and then override this setting of _axisAlignment in the
setAxisAlingment method. I've also removed the lazy updating
optimization you've added to the top of setAxisAlignment to avoid
potential problems as well."
on the screen, it looks more aesthetically pleasing to have a larger
gap between lines than is given by default. I added a new parameter,
lineSpacing, in the Text class to allow the line spacing to be adjustable
by the application. The default value is 0 meaning there is no extra
spacing given. The value should be given as a percentage of the character
height. A good value for longer paragraphs is 0.25 (25%) or more."
