OSG Shader GLSL 4.3 使用纹理 例子

OSG 中使用纹理shader 例子

#include <osgViewer/Viewer>
#include <osgDB/ReadFile>
#include <osg/Shape>
#include <osg/Shapedrawable>
#include <osg/MatrixTransform>
#include <osg/Texture2D>

static char * vertexShader= {
		"#version 430 \n"
		"layout (location=0) in vec3 VertexPosition;\n"
		"layout (location=1) in vec2 TexCorrd;\n"
		"uniform mat4 MVP;"
		"out vec2 Corrd;\n"
		"void main()\n"
		"{\n"
		"   Corrd = TexCorrd;"
		"   gl_Position = MVP * vec4(VertexPosition,1.0);\n"
		"}\n"
};

static char * fragShader ={
		"#version 430 \n"
		"uniform sampler2D sampler2d_0;\n"
		"uniform sampler2D sampler2d_1;\n"
		"layout (location=0) out vec4 FragColor;\n"
		"in vec2 Corrd;\n"
		"void main() {\n"
		"   vec4 tmpColor = texture(sampler2d_0, Corrd);"
		"   if(Corrd[1] > 0.5 ) \n"
		"		   tmpColor = texture(sampler2d_1, Corrd); \n"
		"   FragColor = tmpColor ;\n"
		"}\n"
};

class MVPCallback: public osg::Uniform::Callback
{
public:
		MVPCallback(osg::Camera * camera):mCamera(camera){
		}
		virtual void operator()( osg::Uniform* uniform, osg::NodeVisitor* nv){
				osg::Matrix modelView = mCamera->getViewMatrix();
				osg::Matrix projectM = mCamera->getProjectionMatrix();
				uniform->set(modelView * projectM);
		}  

private:
		osg::Camera * mCamera;
}; 

osg::Node * createNode()
{
		osg::Geode * geode = new osg::Geode;

		osg::Geometry * gm = new osg::Geometry;

		osg::Vec3Array * vertexArray = new osg::Vec3Array;
		vertexArray->push_back(osg::Vec3(0,0,0));
		vertexArray->push_back(osg::Vec3(1,0,0));
		vertexArray->push_back(osg::Vec3(1,0,1));
		vertexArray->push_back(osg::Vec3(0,0,1));
		gm->setVertexArray(vertexArray);

		osg::Vec3Array * normalArray = new osg::Vec3Array;
		normalArray->push_back(osg::Vec3(0,-1,0));
		gm->setNormalArray(normalArray);
		gm->setNormalBinding(osg::Geometry::BIND_OVERALL);

		osg::Vec2Array* texcoords = new osg::Vec2Array(4);
		(*texcoords)[0].set(0.0f,0.0f);
		(*texcoords)[1].set(1.0f,0.0f);
		(*texcoords)[2].set(1.0f,1.0f);
		(*texcoords)[3].set(0.0f,1.0f);
		gm->setTexCoordArray(0,texcoords);

		gm->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS,0,vertexArray->size()));
		geode->addDrawable(gm);

		osg::StateSet* stateset = gm->getOrCreateStateSet();

		osg::Texture2D * texture0 = new osg::Texture2D;
		texture0->setDataVariance(osg::Object::DYNAMIC); // protect from being optimized away as static state.
		texture0->setImage(osgDB::readImageFile("Images/forestWall.png"));
		stateset->setTextureAttributeAndModes(0,texture0,osg::StateAttribute::ON);

		osg::Texture2D * texture1 = new osg::Texture2D;
		texture1->setDataVariance(osg::Object::DYNAMIC); // protect from being optimized away as static state.
		texture1->setImage(osgDB::readImageFile("Images/purpleFlowers.png"));
		stateset->setTextureAttributeAndModes(1,texture1,osg::StateAttribute::ON);

		gm->setVertexAttribArray(0,vertexArray);
		gm->setVertexAttribBinding(0, osg::Geometry::BIND_PER_VERTEX);

		gm->setVertexAttribArray(1,texcoords);
		gm->setVertexAttribBinding(1, osg::Geometry::BIND_PER_VERTEX);

		return geode;
}
int main()
{
		  osg::ref_ptr<osgViewer::Viewer> viewer  = new osgViewer::Viewer;

		osg::Group * root = new osg::Group;

		osg::Node * node = createNode();
		root->addChild(node);	

		osg::StateSet * ss = node->getOrCreateStateSet();
		osg::Program * program = new osg::Program;
		program->addBindFragDataLocation("VertexPosition",0);
		program->addBindFragDataLocation("TexCorrd",1);

		osg::Shader * vS = new osg::Shader(osg::Shader::FRAGMENT,fragShader);
		osg::Shader * fS = new osg::Shader(osg::Shader::VERTEX,vertexShader);
		program->addShader(vS);
		program->addShader(fS);
		ss->setAttributeAndModes(program,osg::StateAttribute::ON);

		osg::Uniform* MVPUniform = new osg::Uniform( "MVP",osg::Matrix());
		MVPUniform->setUpdateCallback(new MVPCallback(viewer->getCamera()));
		ss->addUniform(MVPUniform);
		osg::Uniform* sample0 = new osg::Uniform("sampler2d_0",0);
		ss->addUniform(sample0);

		osg::Uniform* sample1 = new osg::Uniform("sampler2d_1",1);
		ss->addUniform(sample1);

		viewer->setSceneData(root);
		viewer->setUpViewInWindow(35, 35, 1024, 800);

		return viewer->run();
}