Hi,
i want to use texture buffer objects within my program.
At the beginning i managed to get tbo's to work within a pure opengl
application.
This is what i did:
1. create tbo
Code:
// create buffer object
glGenBuffers(1, tbo);
glBindBuffer(GL_TEXTURE_BUFFER_EXT, *tbo);
// initialize buffer object
unsigned int size = mesh_width * mesh_height * 4 * sizeof(float);
glBufferData(GL_TEXTURE_BUFFER_EXT, size, 0, GL_DYNAMIC_DRAW);
//tex
glGenTextures(1, tex);
glBindTexture(GL_TEXTURE_BUFFER_EXT, *tex);
glTexBufferEXT(GL_TEXTURE_BUFFER_EXT, GL_RGBA32F_ARB, *tbo);
glBindBuffer(GL_TEXTURE_BUFFER_EXT, 0);
2. set data of the tbo
Code:
glBindBuffer(GL_TEXTURE_BUFFER_EXT, tbo);
p = (float4*) glMapBuffer(GL_TEXTURE_BUFFER_EXT, GL_WRITE_ONLY);
for (int u = 0; u < mesh_height; u++) {
for (int v = 0; v < mesh_width; v++) {
p[u + (v * mesh_width)][0] = ((float) u / mesh_height) * 2 -
(1.0);
p[u + (v * mesh_width)][1] = ((float) v / mesh_width) * 2 -
(1.0);
p[u + (v * mesh_width)][2] = 0.0f;
p[u + (v * mesh_width)][3] = 1.0f;
}
}
glUnmapBuffer(GL_TEXTURE_BUFFER_EXT);
glBindBuffer(GL_TEXTURE_BUFFER_EXT, 0);
3. set uniform
Code:
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_BUFFER_EXT, displacementTex);
And now i wanted to port this into osg. I have no idea how to create the tbo.
I managed to get as far as:
Code:
osg::BufferObject::Extensions* ext = osg::BufferObject::getExtensions(
_gc->getState()->getContextID(), true);
ext->glBindBuffer(GL_TEXTURE_BUFFER_EXT, tbo);
unsigned int size = mesh_width * mesh_height * 4 * sizeof(float);
ext->glBufferData(GL_TEXTURE_BUFFER_EXT, size, 0, GL_DYNAMIC_DRAW);
Do i have to create a osg::Texture::TextureObject Object to bind it to the
BufferObject? I do not know how to port these calls:
Code:
glBindTexture(GL_TEXTURE_BUFFER_EXT, *tex);
glTexBufferEXT(GL_TEXTURE_BUFFER_EXT, GL_RGBA32F_ARB, *tbo);
My goal is to create a float buffer object by that i can access a huge amount
of floats within my shader.
Thank you!
Cheers,
Johannes
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=20521#20521
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