OSG实现正八面体剖分成球

Posted 2020-10-11 唐淼

#include<Windows.h>
#include<osg/Node>
#include<osg/Geode>
#include<osg/Group>
#include <osg/Geometry>
#include<osgUtil/Optimizer>
#include <cmath>
#include<iostream>
#include<osgViewer/Viewer>
#include<osgDB/ReadFile>
#include<osgDB/WriteFile>
std::set<osg::Vec3> pointSet;
osg::ref_ptr<osg::Geode> geode = new osg::Geode;
void subdivide(float v1x, float v1y, float v1z,
	float v2x, float v2y, float v2z,
	float v3x, float v3y, float v3z,
	int level) {
	if (level == 0) {
		// Reached desired tessellation level, emit triangle.
		osg::Vec3 v1Temp = osg::Vec3(v1x, v1y, v1z);
		osg::Vec3 v2Temp = osg::Vec3(v2x, v2y, v2z);
		osg::Vec3 v3Temp = osg::Vec3(v3x, v3y, v3z);
		v1Temp.normalize();
		v2Temp.normalize();
		v3Temp.normalize();
		pointSet.insert(v1Temp);
		pointSet.insert(v2Temp);
		pointSet.insert(v3Temp);
		osg::ref_ptr<osg::Vec3Array> vertex = new osg::Vec3Array;
		vertex->push_back(v1Temp);
		vertex->push_back(v2Temp);
		vertex->push_back(v3Temp);
		osg::ref_ptr < osg::Geometry>geometry = new osg::Geometry;
		geometry->setVertexArray(vertex.get());
		geometry->setNormalArray(vertex.get());
		geometry->setNormalBinding(osg::Geometry::BIND_PER_VERTEX);
		geometry->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::TRIANGLES, 0, vertex->size()));
		geode->addDrawable(geometry);
		/*drawTriangle(v1x, v1y, v1z,
			v2x, v2y, v2z,
			v3x, v3y, v3z);
			*/
	}
	else {
		// Calculate middle of first edge...
		float v12x = 0.5f * (v1x + v2x);
		float v12y = 0.5f * (v1y + v2y);
		float v12z = 0.5f * (v1z + v2z);
		// ... and renormalize it to get a point on the sphere.
		float s = 1.0f / sqrt(v12x * v12x + v12y * v12y + v12z * v12z);
		v12x *= s;
		v12y *= s;
		v12z *= s;

		// Same thing for the middle of the other two edges.
		float v13x = 0.5f * (v1x + v3x);
		float v13y = 0.5f * (v1y + v3y);
		float v13z = 0.5f * (v1z + v3z);

		 s = 1.0f / sqrt(v13x * v13x + v13y * v13y + v13z * v13z);
		v13x *= s;
		v13y *= s;
		v13z *= s;

		float v23x = 0.5f * (v2x + v3x);
		float v23y = 0.5f * (v2y + v3y);
		float v23z = 0.5f * (v2z + v3z);
		 s = 1.0f / sqrt(v23x * v23x + v23y * v23y + v23z * v23z);
		v23x *= s;
		v23y *= s;
		v23z *= s;

		// Make the recursive calls.
		subdivide(v1x, v1y, v1z,
			v12x, v12y, v12z,
			v13x, v13y, v13z,
			level - 1);
		subdivide(v12x, v12y, v12z,
			v2x, v2y, v2z,
			v23x, v23y, v23z,
			level - 1);
		subdivide(v13x, v13y, v13z,
			v23x, v23y, v23z,
			v3x, v3y, v3z,
			level - 1);
		subdivide(v12x, v12y, v12z,
			v23x, v23y, v23z,
			v13x, v13y, v13z,
			level - 1);
	}
}
int main()
{
	osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;
	
	int level = 3;
	subdivide(0.000000, 0.000000, 1.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, level);
	subdivide(0.000000, 0.000000, 1.000000, -1.000000,0.000000, 0.000000, 0.000000, 1.000000, 0.000000, level);
	subdivide(0.000000, 0.000000, 1.000000, -1.000000, 0.000000, 0.000000, -0.000000 ,- 1.000000,0.000000, level);
	subdivide(0.000000, 0.000000, 1.000000, 1.000000, 0.000000, 0.000000, -0.000000, -1.000000, 0.000000, level);

	subdivide(0.000000, 0.000000, -1.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, level);
	subdivide(0.000000, 0.000000, -1.000000, -1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, level);
	subdivide(0.000000, 0.000000, -1.000000, -1.000000, 0.000000, 0.000000, 0.000000, -1.000000, 0.000000, level);
	subdivide(0.000000, 0.000000, -1.000000, 1.000000, 0.000000, 0.000000, 0.000000, -1.000000, 0.000000, level);

	osg::ref_ptr<osg::Group> node = new osg::Group;
	node->addChild(geode);
	osgUtil::Optimizer optimizer;
	optimizer.optimize(node.get());

	viewer->setSceneData(node.get());
	viewer->realize();
	viewer->run();
	return 0;
}