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