OpenSceneGraph/examples/osgcomputeshaders/osgcomputeshaders.cpp
Robert Osfield dd996a3289 Introduced CMake option OSG_PROVIDE_READFILE option that defaults to ON, but when switched to OFF disables the building of the osgDB::read*File() methods,
forcing users to use osgDB::readRef*File() methods.  The later is preferable as it closes a potential threading bug when using paging databases in conjunction
with the osgDB::Registry Object Cache.  This threading bug occurs when one thread gets an object from the Cache via an osgDB::read*File() call where only
a pointer to the object is passed back, so taking a reference to the object is delayed till it gets reassigned to a ref_ptr<>, but at the same time another
thread calls a flush of the Object Cache deleting this object as it's referenceCount is now zero.  Using osgDB::readREf*File() makes sure the a ref_ptr<> is
passed back and the referenceCount never goes to zero.

To ensure the OSG builds when OSG_PROVIDE_READFILE is to OFF the many cases of osgDB::read*File() usage had to be replaced with a ref_ptr<> osgDB::readRef*File()
usage.  The avoid this change causing lots of other client code to be rewritten to handle the use of ref_ptr<> in place of C pointer I introduced a serious of
templte methods in various class to adapt ref_ptr<> to the underly C pointer to be passed to old OSG API's, example of this is found in include/osg/Group:

    bool addChild(Node* child); // old method which can only be used with a Node*

    tempalte<class T> bool addChild(const osg::ref_ptr<T>& child) { return addChild(child.get()); } // adapter template method

These changes together cover 149 modified files, so it's a large submission. This extent of changes are warrent to make use of the Object Cache
and multi-threaded loaded more robust.



git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@15164 16af8721-9629-0410-8352-f15c8da7e697
2015-10-22 13:42:19 +00:00

93 lines
4.5 KiB
C++

/* -*-c++-*- OpenSceneGraph example, osgcomputeshaders.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
// Written by Wang Rui
// This example can work only if GL version is 4.3 or greater
#include <osg/Texture2D>
#include <osg/Geometry>
#include <osg/Geode>
#include <osgDB/ReadFile>
#include <osgGA/StateSetManipulator>
#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>
static const char* computeSrc = {
"#version 430\n"
"uniform float osg_FrameTime;\n"
"layout (r32f, binding =0) uniform image2D targetTex;\n"
"layout (local_size_x = 16, local_size_y = 16) in;\n"
"void main() {\n"
" ivec2 storePos = ivec2(gl_GlobalInvocationID.xy);\n"
" float coeffcient = 0.5*sin(float(gl_WorkGroupID.x + gl_WorkGroupID.y)*0.1 + osg_FrameTime);\n"
" coeffcient *= length(vec2(ivec2(gl_LocalInvocationID.xy) - ivec2(8)) / vec2(8.0));\n"
" imageStore(targetTex, storePos, vec4(1.0-coeffcient, 0.0, 0.0, 0.0));\n"
"}\n"
};
int main( int argc, char** argv )
{
osg::ArgumentParser arguments( &argc, argv );
// Create the texture as both the output of compute shader and the input of a normal quad
osg::ref_ptr<osg::Texture2D> tex2D = new osg::Texture2D;
tex2D->setTextureSize( 512, 512 );
tex2D->setFilter( osg::Texture2D::MIN_FILTER, osg::Texture2D::LINEAR );
tex2D->setFilter( osg::Texture2D::MAG_FILTER, osg::Texture2D::LINEAR );
tex2D->setInternalFormat( GL_R32F );
tex2D->setSourceFormat( GL_RED );
tex2D->setSourceType( GL_FLOAT );
tex2D->bindToImageUnit( 0, osg::Texture::WRITE_ONLY ); // So we can use 'image2D' in the compute shader
// The compute shader can't work with other kinds of shaders
// It also requires the work group numbers. Setting them to 0 will disable the compute shader
osg::ref_ptr<osg::Program> computeProg = new osg::Program;
computeProg->setComputeGroups( 512/16, 512/16, 1 );
computeProg->addShader( new osg::Shader(osg::Shader::COMPUTE, computeSrc) );
// Create a node for outputting to the texture.
// It is OK to have just an empty node here, but seems inbuilt uniforms like osg_FrameTime won't work then.
// TODO: maybe we can have a custom drawable which also will implement glMemoryBarrier?
osg::ref_ptr<osg::Node> sourceNode = osgDB::readRefNodeFile("axes.osgt");
if ( !sourceNode ) sourceNode = new osg::Node;
sourceNode->setDataVariance( osg::Object::DYNAMIC );
sourceNode->getOrCreateStateSet()->setAttributeAndModes( computeProg.get() );
sourceNode->getOrCreateStateSet()->addUniform( new osg::Uniform("targetTex", (int)0) );
sourceNode->getOrCreateStateSet()->setTextureAttributeAndModes( 0, tex2D.get() );
// Display the texture on a quad. We will also be able to operate on the data if reading back to CPU side
osg::Geometry* geom = osg::createTexturedQuadGeometry(
osg::Vec3(), osg::Vec3(1.0f,0.0f,0.0f), osg::Vec3(0.0f,0.0f,1.0f) );
osg::ref_ptr<osg::Geode> quad = new osg::Geode;
quad->addDrawable( geom );
quad->getOrCreateStateSet()->setMode( GL_LIGHTING, osg::StateAttribute::OFF );
quad->getOrCreateStateSet()->setTextureAttributeAndModes( 0, tex2D.get() );
// Create the scene graph and start the viewer
osg::ref_ptr<osg::Group> scene = new osg::Group;
scene->addChild( sourceNode );
scene->addChild( quad.get() );
osgViewer::Viewer viewer;
viewer.addEventHandler( new osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()) );
viewer.addEventHandler( new osgViewer::StatsHandler );
viewer.addEventHandler( new osgViewer::WindowSizeHandler );
viewer.setSceneData( scene.get() );
return viewer.run();
}