Hi. Sorry I don't on my computer right now, but it seems you are not providing vertex shaders. I'm not sure, but that might cause trouble. I'll get back to the issue tommorow or on Monday.

Cheers
Sebastian
--
Sent from my Android phone with GMX Mail. Please excuse my brevity.
On 9/2/17, 21:36 antiro black <antir...@gmail.com> wrote:

Hi Sebastian,

I'm compiling under debian jessie 64 bits and am running a NVIDIA GTX 970. The drivers have been updates recently and I am running version 384.69 now.

I included a compilable minimal example based on the osgmultiplerendertargets example. Without VertexAttributeAliasing it generates two texture using MRT, a red and a green one, it then combines these in a second pass to generate the final texture (yellow). (The red and green intermediate textures are shown in small quads to the side.)

When I enable the attribute aliasing (as in the included code), the two textures generated in the MRT pass turn into gradients, as if something has gone wrong with the mapping.

Screenshots:
The expected result (which I get without attribute aliasing): https://ibb.co/kHEogv
The result with aliasing: https://ibb.co/d9cfuF

Code:
/* OpenSceneGraph example, osgmultiplerendertargets.
*
* 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.
*/

#include <osg/GLExtensions>
#include <osg/Node>
#include <osg/Geometry>
#include <osg/Notify>
#include <osg/MatrixTransform>
#include <osg/Texture2D>
#include <osg/TextureRectangle>
#include <osg/ColorMask>
#include <osg/Material>
#include <osg/Capability>

#include <osgGA/TrackballManipulator>
#include <osgGA/FlightManipulator>
#include <osgGA/DriveManipulator>

#include <osgViewer/Viewer>

#include <iostream>
#include <stdio.h>

#include <osg/PolygonMode>
//#include "RenderingUtility.h" //to easily view intermediate textures
//
// Below is relatively straight forward example of using the OpenGL multiple render targets (MRT) extension
// to FrameBufferObjects/GLSL shaders.
//
// Another, more sophisticated MRT example can be found in the osgstereomatch example.
//

osg::Geode *createScreenQuad(float width,
float height,
float scale,
osg::Vec3 corner)
{
osg::Geometry* geom = osg::createTexturedQuadGeometry(
corner,
osg::Vec3(width, 0, 0),
osg::Vec3(0, height, 0),
0,
0,
scale,
scale);
osg::ref_ptr<osg::Geode> quad = new osg::Geode;
quad->addDrawable(geom);
int values = osg::StateAttribute::OFF | osg::StateAttribute::PROTECTED;
quad->getOrCreateStateSet()->setAttribute(
new osg::PolygonMode(osg::PolygonMode::FRONT_AND_BACK,
osg::PolygonMode::FILL),
values);
quad->getOrCreateStateSet()->setMode(GL_LIGHTING, values);
return quad.release();
}

osg::Camera *createHUDCamera(double left=0,
double right=1,
double bottom=0,
double top=1)
{
osg::ref_ptr<osg::Camera> camera = new osg::Camera;
camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
camera->setClearMask(GL_DEPTH_BUFFER_BIT);
camera->setRenderOrder(osg::Camera::POST_RENDER);
camera->setAllowEventFocus(false);
camera->setProjectionMatrix(osg::Matrix::ortho2D(left, right, bottom, top));
camera->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
return camera.release();
}

osg::ref_ptr<osg::Camera> createTextureDisplayQuad(
const osg::Vec3 &pos,
osg::StateAttribute *tex,
float scale,
float width=0.3,
float height=0.2)
{
osg::ref_ptr<osg::Camera> hc = createHUDCamera();
hc->addChild(createScreenQuad(width, height, scale, pos));
hc->getOrCreateStateSet()->setTextureAttributeAndModes(0, tex);
return hc;
}

// The callback modifies an input image.
struct MyCameraPostDrawCallback : public osg::Camera::DrawCallback
{
MyCameraPostDrawCallback(osg::Image* image):
_image(image)
{
}

virtual void operator () (const osg::Camera& /*camera*/) const
{
if (_image && _image->getPixelFormat()==GL_RGBA && _image->getDataType()==GL_UNSIGNED_BYTE)
{
// we'll pick out the center 1/2 of the whole image,
int column_start = _image->s()/4;
int column_end = 3*column_start;

int row_start = _image->t()/4;
int row_end = 3*row_start;

// and then halve their contribution
for(int r=row_start; r<row_end; ++r)
{
unsigned char* data = "" r);
for(int c=column_start; c<column_end; ++c)
{
(*data) = (*data)/2; ++data;
(*data) = (*data)/2; ++data;
(*data) = (*data)/2; ++data;
(*data) = 255; ++data;
}
}

_image->dirty();
}
else if (_image && _image->getPixelFormat()==GL_RGBA && _image->getDataType()==GL_FLOAT)
{
// we'll pick out the center 1/2 of the whole image,
int column_start = _image->s()/4;
int column_end = 3*column_start;

int row_start = _image->t()/4;
int row_end = 3*row_start;

// and then halve their contribution
for(int r=row_start; r<row_end; ++r)
{
float* data = "" r);
for(int c=column_start; c<column_end; ++c)
{
(*data) = (*data)/2.0; ++data;
(*data) = (*data)/2.0; ++data;
(*data) = (*data)/2.0; ++data;
(*data) = 1.0f; ++data;
}
}

_image->dirty();

//print out the first three values
float* data = "" 0);
fprintf(stderr,"Float pixel data: r %e g %e b %e\n", data[0], data[1], data[2]);
}
}

osg::Image* _image;
};

#define NUM_TEXTURES 2

// The quad geometry is used by the render to texture camera to generate multiple textures.
osg::Group* createRTTQuad(unsigned int tex_width, unsigned int tex_height, bool useHDR)
{
osg::Group *top_group = new osg::Group;

osg::ref_ptr<osg::Geode> quad_geode = new osg::Geode;

osg::ref_ptr<osg::Vec3Array> quad_coords = new osg::Vec3Array; // vertex coords
// counter-clockwise
quad_coords->push_back(osg::Vec3d(0, 0, -1));
quad_coords->push_back(osg::Vec3d(1, 0, -1));
quad_coords->push_back(osg::Vec3d(1, 1, -1));
quad_coords->push_back(osg::Vec3d(0, 1, -1));

osg::ref_ptr<osg::Vec2Array> quad_tcoords = new osg::Vec2Array; // texture coords
quad_tcoords->push_back(osg::Vec2(0, 0));
quad_tcoords->push_back(osg::Vec2(tex_width, 0));
quad_tcoords->push_back(osg::Vec2(tex_width, tex_height));
quad_tcoords->push_back(osg::Vec2(0, tex_height));

osg::ref_ptr<osg::Geometry> quad_geom = new osg::Geometry;
osg::ref_ptr<osg::DrawArrays> quad_da = new osg::DrawArrays(osg::PrimitiveSet::QUADS,0,4);

osg::ref_ptr<osg::Vec4Array> quad_colors = new osg::Vec4Array;
quad_colors->push_back(osg::Vec4(1.0f,1.0f,1.0f,1.0f));

quad_geom->setVertexArray(quad_coords.get());
quad_geom->setTexCoordArray(0, quad_tcoords.get());
quad_geom->addPrimitiveSet(quad_da.get());
quad_geom->setColorArray(quad_colors.get(), osg::Array::BIND_OVERALL);

osg::StateSet *stateset = quad_geom->getOrCreateStateSet();
stateset->setMode(GL_LIGHTING,osg::StateAttribute::OFF);

stateset->addUniform(new osg::Uniform("width", (int)tex_width));

// Attach shader, glFragData is used to create data for multiple render targets

if (useHDR) {
static const char *shaderSource = {
"uniform int width;"
"void main(void)\n"
"{\n"
" gl_FragData[0] = vec4(-1e-12,0,0,1);\n"
" gl_FragData[1] = vec4(0,1e-12,0,1);\n"
" gl_FragData[2] = vec4(0,0,1e-12,1);\n"
" gl_FragData[3] = vec4(0,0,1e-12,1);\n"
"}\n"
};

osg::ref_ptr<osg::Shader> fshader = new osg::Shader( osg::Shader::FRAGMENT , shaderSource);
osg::ref_ptr<osg::Program> program = new osg::Program;
program->addShader(fshader.get());
stateset->setAttributeAndModes(program.get(), osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE );
} else {
static const char *shaderSource = {
"uniform int width;"
"void main(void)\n"
"{\n"
" gl_FragData[0] = vec4(1,0,0,1);\n"
" gl_FragData[1] = vec4(0,1,0,1);\n"
" gl_FragData[2] = vec4(0,0,1,1);\n"
" gl_FragData[3] = vec4(0,0,1,1);\n"
"}\n"
};

osg::ref_ptr<osg::Shader> fshader = new osg::Shader( osg::Shader::FRAGMENT , shaderSource);
osg::ref_ptr<osg::Program> program = new osg::Program;
program->addShader(fshader.get());
stateset->setAttributeAndModes(program.get(), osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE );
}

quad_geode->addDrawable(quad_geom.get());

top_group->addChild(quad_geode.get());

return top_group;
}

osg::TextureRectangle* textureRect[NUM_TEXTURES] = {0,0}; //moved to global scope to easily view intermediate textures
// Here a scene consisting of a single quad is created. This scene is viewed by the screen camera.
// The quad is textured using a shader and the multiple textures generated in the RTT stage.
osg::Node* createScene(osg::Node* cam_subgraph, unsigned int tex_width, unsigned int tex_height, bool useHDR, bool useImage, bool useMultiSample)
{
if (!cam_subgraph) return 0;

// create a group to contain the quad and the pre render camera.
osg::Group* parent = new osg::Group;

// textures to render to and to use for texturing of the final quad
//osg::TextureRectangle* textureRect[NUM_TEXTURES] = {0,0,0,0};

for (int i=0;i<NUM_TEXTURES;i++) {
textureRect[i] = new osg::TextureRectangle;
textureRect[i]->setTextureSize(tex_width, tex_height);
textureRect[i]->setInternalFormat(GL_RGBA);
textureRect[i]->setFilter(osg::Texture2D::MIN_FILTER,osg::Texture2D::LINEAR);
textureRect[i]->setFilter(osg::Texture2D::MAG_FILTER,osg::Texture2D::LINEAR);

if (useHDR)
{
// Default HDR format
textureRect[i]->setInternalFormat(GL_RGBA32F_ARB);

// GL_FLOAT_RGBA32_NV might be supported on pre 8-series GPUs
//textureRect[i]->setInternalFormat(GL_FLOAT_RGBA32_NV);

// GL_RGBA16F_ARB can be used with this example,
// but modify e-12 and e12 in the shaders accordingly
//textureRect[i]->setInternalFormat(GL_RGBA16F_ARB);

textureRect[i]->setSourceFormat(GL_RGBA);
textureRect[i]->setSourceType(GL_FLOAT);
}
}

// first create the geometry of the quad
{
osg::Geometry* polyGeom = new osg::Geometry();

polyGeom->setSupportsDisplayList(false);

osg::Vec3Array* vertices = new osg::Vec3Array;
osg::Vec2Array* texcoords = new osg::Vec2Array;

vertices->push_back(osg::Vec3d(0,0,0));
texcoords->push_back(osg::Vec2(0,0));

vertices->push_back(osg::Vec3d(1,0,0));
texcoords->push_back(osg::Vec2(tex_width,0));

vertices->push_back(osg::Vec3d(1,0,1));
texcoords->push_back(osg::Vec2(tex_width,tex_height));

vertices->push_back(osg::Vec3d(0,0,1));
texcoords->push_back(osg::Vec2(0,tex_height));

polyGeom->setVertexArray(vertices);
polyGeom->setTexCoordArray(0,texcoords);

osg::Vec4Array* colors = new osg::Vec4Array;
colors->push_back(osg::Vec4(1.0f,1.0f,1.0f,1.0f));
polyGeom->setColorArray(colors, osg::Array::BIND_OVERALL);

polyGeom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS,0,vertices->size()));

// now we need to add the textures (generated by RTT) to the Drawable.
osg::StateSet* stateset = new osg::StateSet;
for (int i=0;i<NUM_TEXTURES;i++){
stateset->setTextureAttributeAndModes(i, textureRect[i], osg::StateAttribute::ON);
}

polyGeom->setStateSet(stateset);

// Attach a shader to the final quad to combine the input textures.
if (useHDR) {
static const char *shaderSource = {
"uniform sampler2DRect textureID0;\n"
"uniform sampler2DRect textureID1;\n"
"uniform sampler2DRect textureID2;\n"
"uniform sampler2DRect textureID3;\n"
"uniform float width;\n"
"uniform float height; \n"
"void main(void)\n"
"{\n"
" gl_FragData[0] = \n"
" vec4( -1e12 * texture2DRect( textureID0, gl_TexCoord[0].st ).rgb, 1) + \n"
" vec4( 1e12 * texture2DRect( textureID1, gl_TexCoord[0].st ).rgb, 1) + \n"
" vec4( 1e12 * texture2DRect( textureID2, gl_TexCoord[0].st ).rgb, 1) + \n"
" vec4(-0.5e12 * texture2DRect( textureID3, gl_TexCoord[0].st ).rgb, 1); \n"
"}\n"
};
osg::ref_ptr<osg::Shader> fshader = new osg::Shader( osg::Shader::FRAGMENT , shaderSource);
osg::ref_ptr<osg::Program> program = new osg::Program;
program->addShader( fshader.get());
stateset->setAttributeAndModes( program.get(), osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE );
} else {
static const char *shaderSource = {
"uniform sampler2DRect textureID0;\n"
"uniform sampler2DRect textureID1;\n"
"uniform sampler2DRect textureID2;\n"
"uniform sampler2DRect textureID3;\n"
"void main(void)\n"
"{\n"
" gl_FragData[0] = \n"
" vec4(texture2DRect( textureID0, gl_TexCoord[0].st ).rgb, 1) + \n"
" vec4(texture2DRect( textureID1, gl_TexCoord[0].st ).rgb, 1) + \n"
" vec4(texture2DRect( textureID2, gl_TexCoord[0].st ).rgb, 1) + \n"
" -0.5*vec4(texture2DRect( textureID3, gl_TexCoord[0].st ).rgb, 1); \n"
"}\n"
};
osg::ref_ptr<osg::Shader> fshader = new osg::Shader( osg::Shader::FRAGMENT , shaderSource);
osg::ref_ptr<osg::Program> program = new osg::Program;
program->addShader( fshader.get());
stateset->setAttributeAndModes( program.get(), osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE );

}

stateset->addUniform(new osg::Uniform("textureID0", 0));
stateset->addUniform(new osg::Uniform("textureID1", 1));
stateset->addUniform(new osg::Uniform("textureID2", 2));
stateset->addUniform(new osg::Uniform("textureID3", 3));

//stateset->setDataVariance(osg::Object::DYNAMIC);

osg::Geode* geode = new osg::Geode();
geode->addDrawable(polyGeom);

parent->addChild(geode);
}

// now create the camera to do the multiple render to texture
{
osg::Camera* camera = new osg::Camera;

// set up the background color and clear mask.
camera->setClearColor(osg::Vec4(0.1f,0.1f,0.3f,1.0f));
camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// the camera is going to look at our input quad
camera->setProjectionMatrix(osg::Matrix::ortho2D(0,1,0,1));
camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
camera->setViewMatrix(osg::Matrix::identity());

// set viewport
camera->setViewport(0, 0, tex_width, tex_height);

// set the camera to render before the main camera.
camera->setRenderOrder(osg::Camera::PRE_RENDER);

// tell the camera to use OpenGL frame buffer objects
camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);

// attach the textures to use
for (int i=0; i<NUM_TEXTURES; i++) {
if (useMultiSample)
camera->attach(osg::Camera::BufferComponent(osg::Camera::COLOR_BUFFER0+i), textureRect[i], 0, 0, false, 4, 4);
else
camera->attach(osg::Camera::BufferComponent(osg::Camera::COLOR_BUFFER0+i), textureRect[i]);

}

#if 0
// test for new glEnablei/glDisablei functionality.
camera->getOrCreateStateSet()->setAttribute(new osg::Enablei(GL_BLEND, 0));
camera->getOrCreateStateSet()->setAttribute(new osg::Disablei(GL_BLEND, 1));
#endif

// we can also read back any of the targets as an image, modify this image and push it back
if (useImage) {
// which texture to get the image from
const int tex_to_get = 0;

osg::Image* image = new osg::Image;
if (useHDR) {
image->allocateImage(tex_width, tex_height, 1, GL_RGBA, GL_FLOAT);
} else {
image->allocateImage(tex_width, tex_height, 1, GL_RGBA, GL_UNSIGNED_BYTE);
}

// attach the image so its copied on each frame.
camera->attach(osg::Camera::BufferComponent(osg::Camera::COLOR_BUFFER0 + tex_to_get), image);

camera->setPostDrawCallback(new MyCameraPostDrawCallback(image));

// push back the image to the texture
textureRect[tex_to_get]->setImage(0, image);
}

// add the subgraph to render
camera->addChild(cam_subgraph);

parent->addChild(camera);
}

return parent;
}

int main( int argc, char **argv )
{
// use an ArgumentParser object to manage the program arguments.
osg::ArgumentParser arguments(&argc,argv);

// set up the usage document, in case we need to print out how to use this program.
arguments.getApplicationUsage()->setDescription(arguments.getApplicationName() + " demonstrates the use of multiple render targets (MRT) with frame buffer objects (FBOs). A render to texture (RTT) camera is used to render to four textures using a single shader. The four textures are then combined to texture the viewed geometry.");
arguments.getApplicationUsage()->setCommandLineUsage(arguments.getApplicationName()+" [options] ...");
arguments.getApplicationUsage()->addCommandLineOption("-h or --help","Display this information.");
arguments.getApplicationUsage()->addCommandLineOption("--width","Set the width of the render to texture.");
arguments.getApplicationUsage()->addCommandLineOption("--height","Set the height of the render to texture.");
arguments.getApplicationUsage()->addCommandLineOption("--image","Render one of the targets to an image, then apply a post draw callback to modify it and use this image to update the final texture. Print some texture values when using HDR.");
arguments.getApplicationUsage()->addCommandLineOption("--hdr","Use high dynamic range (HDR). Create floating point textures to render to.");

// construct the viewer.
osgViewer::Viewer viewer(arguments);

// if user request help write it out to cout.
if (arguments.read("-h") || arguments.read("--help"))
{
arguments.getApplicationUsage()->write(std::cout);
return 1;
}

unsigned tex_width = 512;
unsigned tex_height = 512;
while (arguments.read("--width", tex_width)) {}
while (arguments.read("--height", tex_height)) {}

bool useHDR = false;
while (arguments.read("--hdr")) { useHDR = true; }

bool useImage = false;
while (arguments.read("--image")) { useImage = true; }

bool useMultiSample = false;
while (arguments.read("--ms")) { useMultiSample = true; }

osg::Group* subGraph = createRTTQuad(tex_width, tex_height, useHDR);

osg::Group* rootNode = new osg::Group();
rootNode->addChild(createScene(subGraph, tex_width, tex_height, useHDR, useImage, useMultiSample));

rootNode->addChild(createScene(subGraph, tex_width, tex_height, useHDR, useImage, useMultiSample));

//Some code to view the intermediate textures
osg::ref_ptr<osg::Camera> testTex =
createTextureDisplayQuad(osg::Vec3(0, 0.7, 0),
textureRect[0],
tex_width);
osg::ref_ptr<osg::Camera> testTex2 =
createTextureDisplayQuad(osg::Vec3(0, 0.35, 0),
textureRect[1],
tex_width);

rootNode->addChild(testTex);
rootNode->addChild(testTex2);

// add model to the viewer.
viewer.setSceneData( rootNode );
viewer.realize();
viewer.getCamera()->getGraphicsContext()->getState()->setUseVertexAttributeAliasing(true);

return viewer.run();
}




Thank you!!

Cheers,
antiro[/code]

------------------
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http://forum.openscenegraph.org/viewtopic.php?p=71613#71613



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