Hi Sebastian,
thank you for your answer.
I'm trying to use ShaderStorageBufferCallback by osgSSBO example in a minimal
piece of code which is:
Code:
#include <osgViewer/Viewer>
#include <osg/BufferIndexBinding>
using namespace osg;
class ShaderStorageBufferCallback : public osg::StateAttributeCallback
{
public:
void operator() (osg::StateAttribute* attr, osg::NodeVisitor* nv)
{
//if you need to process the data in your app-code , better
leaving it on GPU and processing there, uploading per frame will make it slow
osg::ShaderStorageBufferBinding* ssbb =
static_cast<osg::ShaderStorageBufferBinding*>(attr);
osg::ShaderStorageBufferObject* ssbo
=
static_cast<osg::ShaderStorageBufferObject*>(ssbb->getBufferObject());
osg::FloatArray* array =
static_cast<osg::FloatArray*>(ssbo->getBufferData(0));
float someValue = array->at(0);
osg::notify(INFO) << "someValue now: " << someValue <<
std::endl;
}
};
int mymain(){
FloatArray * dati = new FloatArray;
dati->resize(10, 1.0);
ShaderStorageBufferObject *ssbo = new osg::ShaderStorageBufferObject;
dati->setBufferObject(ssbo);
ShaderStorageBufferBinding * ssbb = new ShaderStorageBufferBinding(2,
ssbo, 0, 10 * sizeof(GLfloat));
ssbb->setUpdateCallback(new ShaderStorageBufferCallback);
Shader * shader = new osg::Shader(osg::Shader::COMPUTE);
shader->loadShaderSourceFromFile("shaders/lightpixels.cs");
osg::ref_ptr<osg::Program> computeProg = new osg::Program;
computeProg->setComputeGroups(512 / 16, 1, 1);
shader->setType(Shader::COMPUTE);
computeProg->addShader(shader);
osg::Geometry * geom = createTexturedQuadGeometry(Vec3(-0.5, 0, -0.5),
Vec3(1.0, 0, 0.0), Vec3(0, 0, 1.0));
geom->getOrCreateStateSet()->setAttributeAndModes(computeProg,
osg::StateAttribute::ON);
geom->getOrCreateStateSet()->setAttributeAndModes(ssbb,
osg::StateAttribute::ON);
osgViewer::Viewer viewer;
viewer.setSceneData(geom);
viewer.setUpViewInWindow(100, 100, 640, 480);
viewer.realize();
while (!viewer.done()){
viewer.frame();
}
return 0;
}
shader code is
Code:
#version 430
layout (local_size_x = 16, local_size_y = 16) in;
//layout (binding=0, rgba32f) uniform image2D targetImage;
layout(std140, binding = 2) buffer dati{float dataBuffer[];};
void main() {
dataBuffer[0] = 348.0;
}
The callback is triggered but it print '1' as value. Like if buffer data was
not changed. How do i use glMemoryBarrier(GL_SHADER_STORAGE_BARRIER_BIT)?
Thank
Luca
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=67074#67074
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