CPP file:
Code:
#include "osgDB/ReadFile"
#include "osgViewer/Viewer"
struct ModelViewProjectionMatrixCallback : public osg::Uniform::Callback {
ModelViewProjectionMatrixCallback(osg::Camera *fCamera) :
_camera(fCamera) {
}
virtual void operator()(osg::Uniform *uniform, osg::NodeVisitor *nv) {
osg::Matrixd viewMatrix = _camera->getViewMatrix();
osg::Matrixd modelMatrix = osg::computeLocalToWorld(nv->getNodePath());
osg::Matrixd modelViewProjectionMatrix = modelMatrix * viewMatrix *
_camera->getProjectionMatrix();
uniform->set(modelViewProjectionMatrix);
}
osg::Camera *_camera;
};
osg::ref_ptr<osg::Program> createProgram(std::string fProgramName, std::string
fVertexShader, std::string fGeometryShader, std::string fFragmentShader)
{
osg::ref_ptr<osg::Shader> vertexShader =
osgDB::readShaderFile(fVertexShader);
osg::ref_ptr<osg::Shader> geometryShader =
osgDB::readShaderFile(fGeometryShader);
osg::ref_ptr<osg::Shader> fragmentShader =
osgDB::readShaderFile(fFragmentShader);
osg::ref_ptr<osg::Program> program = new osg::Program;
program->setName(fProgramName);
program->addShader(vertexShader);
program->addShader(geometryShader);
program->addShader(fragmentShader);
return program.release();
}
int main(int argc, char **argv)
{
// Program
osg::ref_ptr<osg::Program> program = createProgram("SinglePass",
"singlepass.vert", "singlepass.geom", "singlepass.frag");
// Vertices
osg::ref_ptr<osg::Vec3Array> vertices = new osg::Vec3Array;
vertices->push_back(osg::Vec3(0.5f, 0.0f, 0.5f));
// Geometry
osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;
geom->setUseDisplayList(false);
geom->setVertexArray(vertices);
geom->setVertexAttribArray(0, vertices);
geom->addPrimitiveSet(new osg::DrawArrays(GL_POINTS, 0, vertices->size()));
// Geode
osg::ref_ptr<osg::Geode> screenGeode = new osg::Geode;
screenGeode->addDrawable(geom);
// State set
osg::StateSet *geomStateSet = geom->getOrCreateStateSet();
geomStateSet->setAttribute(program);
osg::ref_ptr<osg::Point> point = new osg::Point;
point->setSize(5.0f);
geomStateSet->setAttribute(point);
// Viewer
osgViewer::Viewer viewer;
viewer.setSceneData(screenGeode.get());
viewer.setUpViewInWindow(50, 50, 800, 600, 0);
viewer.getCamera()->setViewport(0, 0, 800, 600);
viewer.getCamera()->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
viewer.getCamera()->setClearColor(osg::Vec4(0.2f, 0.2f, 0.2f, 1.0f));
// MVP
osg::ref_ptr<osg::Uniform> MVP = new osg::Uniform(osg::Uniform::FLOAT_MAT4,
"ModelviewProjection");
MVP->setUpdateCallback(new
ModelViewProjectionMatrixCallback(viewer.getCamera()));
geomStateSet->addUniform(MVP);
return viewer.run();
}
Vertex shader:
Code:
#version 330
in vec4 Position;
out vec4 vPosition;
uniform mat4 ModelviewProjection;
void main()
{
gl_Position = ModelviewProjection * Position;
vPosition = Position;
}
Geometry shader:
Code:
#version 330
layout(points) in;
layout(triangle_strip, max_vertices = 24) out;
in vec4 vPosition[1];
uniform mat4 ModelviewProjection;
uniform mat4 ProjectionMatrix;
uniform mat4 ViewMatrix;
uniform mat4 Modelview;
vec4 objCube[8]; // Object space coordinate of cube corner
vec4 ndcCube[8]; // Normalized device coordinate of cube corner
ivec4 faces[6]; // Vertex indices of the cube faces
void emit_vert(int vert)
{
gl_Position = ndcCube[vert];
EmitVertex();
}
void emit_face(int face)
{
emit_vert(faces[face][1]); emit_vert(faces[face][0]);
emit_vert(faces[face][3]); emit_vert(faces[face][2]);
EndPrimitive();
}
void main()
{
faces[0] = ivec4(0,1,3,2); faces[1] = ivec4(5,4,6,7);
faces[2] = ivec4(4,5,0,1); faces[3] = ivec4(3,2,7,6);
faces[4] = ivec4(0,3,4,7); faces[5] = ivec4(2,1,6,5);
vec4 P = vPosition[0];
vec4 I = vec4(0.25,0,0,0);
vec4 J = vec4(0,0.25,0,0);
vec4 K = vec4(0,0,0.25,0);
objCube[0] = P+K+I+J; objCube[1] = P+K+I-J;
objCube[2] = P+K-I-J; objCube[3] = P+K-I+J;
objCube[4] = P-K+I+J; objCube[5] = P-K+I-J;
objCube[6] = P-K-I-J; objCube[7] = P-K-I+J;
// Transform the corners of the box:
for (int vert = 0; vert < 8; vert++)
ndcCube[vert] = ModelviewProjection * objCube[vert];
// Emit the six faces:
for (int face = 0; face < 6; face++)
emit_face(face);
}
Fragment shader:
Code:
#version 330
out vec4 FragColor;
void main()
{
FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=61030#61030
_______________________________________________
osg-users mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
