昆明网站搭建多少钱,系统之家官网,如何增加网站的索引量,上海网站快速排名1、OSG光照 OSG 全面支持 OpenGL 的光照特性#xff0c;包括材质属性#xff08;material property#xff09;、光照属性#xff08;light property#xff09;和光照模型#xff08;lighting model#xff09;。与 OpenGL 相似#xff0c;OSG 中的光源也是不可见的包括材质属性material property、光照属性light property和光照模型lighting model。与 OpenGL 相似OSG 中的光源也是不可见的而非渲染一个灯泡或其他自然形状。同样光源会创建着色效果但并不创建阴影osgShadow 可以用来创建阴影。
1.1 osg::Light 类 OSG 将 OpenGL 中的 glLight()作了一个 light 状态的类封装用于保存灯光的模式与属性参数信息。osg::Light 类派生自 osg::StateAttribute 类继承了对模式与属性参数信息的操作接口。在 osg::light 类中通过 applyStatestate函数将灯光的状态参数信息应用到 OpenGL 的状态机中。
osg::Light 类包括的属性参数如下
int _lightnum; //灯光数量
Vec4 _ambient; //环境光颜色
Vec4 _diffuse; //漫射光颜色
Vec4 _specular; //镜面光颜色
Vec4 _position; //光源的位置信息
Vec3 _direction; //光源的方向
float _constant_attenuation; //常量衰减
float _linear_attenuation; //线性衰减
float _quadratic_attenuation;//二次方衰减
float _spot_exponent; //指数衰减
float _spot_cutoff; //关闭衰减spread上面的参数应该都比较容易理解。OSG 支持最多 8 个光源即 GL_LIGHT0GL_LIGHT7这与OpenGL 版本也有关系。
1.2 osg::LightSource 类 osg::LightSource 类直接继承自 osg::Group。作为一个灯光管理类继承了 osg::Group 类的管理节点的接口将灯光作为一个节点可以加入到场景图中进行渲染。
osg::LightSource 类中的成员函数为
void setReferenceFrame (ReferenceFrame rf)//设置帧引用帧引用包括如下两个枚举变量
enum ReferenceFrame
{
RELATIVE_RF, //相对帧引用
ABSOLUTE_RF //绝对帧引用
};设置光源的引用帧时不是相对于父节点的帧引用就是相对于绝对坐标的帧默认的设置为RELATIVE_RF设置帧引用为 RELATIVE_RF 同样会设置 CullingActive 的标志量为ON状态并且对它的父节点也起作用否则对它与它所有的父节点都禁用拣选Culling对防止不合适的拣选是必需的如果绝对光源在场景图的深处将会对拣选的时间有影响因此推荐在场景的顶部使用绝对的光源。
1.3 场景中使用光源
在一个场景中添加光源主要包括以下步骤
1指定场景模型的法线。 2允许光照并设置光照状态。 3指定光源属性并关联到场景图形。 对于场景中的模型只有当其中设有单位法线时才会正确地显示光照。当场景中的模型没有指定法线时可以用前面讲到的 osgUtil::SmoothingVisitor 自动生成法线。需要注意的是法向量必须单位化。有时场景中的模型虽然指定了单位法向量但是光照的计算结果过于明亮或过于暗淡可能是缩放变换造成的这时最有效的解决方案是在 StateSet 中允许法线的重放缩模式代码如下
osg::StateSet*state geode-setOrCreateStateSet();
state-setMode(GL_RESCALE_NORMAL, osg::StateAttribute::ON);与在 OpenGL 中相同这一特性可以保证法线在均匀放缩变换时仍然保持单位长度。如果场景中的放缩变换是非均匀的那么读者可以允许法线归一化模式以保证法线为单位长度。由于要进行法线的重新放缩归一化模式往往会耗费大量的时间编程时要尽量避免。归一化模式的代码如下
osg::StateSet*state geode-setOrCreateStateSet();
state-setMode(GL_NORMALIZE, osg::StateAttribute::ON);要在 OSG 中获得光照效果需要允许光照并至少允许一个光源。程序 osgviewer 在默认情况下就是这样做的它在根节点的 StateSet 中已经设置了相应的模式。读者可以在自己的程序中进行相同的设置。下面的代码段用于允许光照并为根节点的 StateSet 允许两个光源GL_LIGHT0 和 GL_LIGHT1
osg::StateSet*state root-getOrCreateStateSet();
state-setMode(GL_LIGHTING, osg::StateAttribute::ON);
state-setMode(GL_LIGHT0, osg::StateAttribute::ON);
state-setMode(GL_LIGHT1, osg::StateAttribute::ON);在场景中添加一个光源可以创建一个 osg::Light 对象以定义光源参数然后将 osg::Light 添加到一个 osg::LightSource 节点中并将 LightSource 节点添加到场景图形。osg::LightSource 是一个包含了唯一的 Light 定义的高效的组节点而由 osg::Light 定义的光源将对整个场景产生影响。下面的代码实现将 osg::Light 添加到 osg::LightSource 对象中
osg::ref_ptrosg::LightSource ls new osg::LightSource;
ls-setLight(light.get());在实际生活中当光照照射到物体上时都会反射等现象所以在对光源的设置完成以后需要设置模型的表面材质下面先看看关于光照的两个示例。
1.4 简单光源示例 #include windows.h
#include osgViewer/Viewer
#include osg/Vec3
#include osg/Vec4
#include osg/Quat
#include osg/Matrix
#include osg/ShapeDrawable
#include osg/Geometry
#include osg/Geode
#include osg/Notify
#include osg/MatrixTransform
#include osg/Texture3D
#include osg/Stencil
#include osg/ColorMask
#include osg/GLExtensions
#include osg/Depth
#include osg/AnimationPath
#include osg/Transform
#include osg/Material
#include osg/NodeCallback
#include osg/Depth
#include osg/CullFace
#include osg/TexMat
#include osg/TexGen
#include osg/TexEnv
#include osg/TextureCubeMap
#include osgViewer/ViewerEventHandlers //事件监听
#include osgGA/StateSetManipulator //事件响应类对渲染状态进行控制
#include osgUtil/Simplifier //简化几何体
#include osgDB/WriteFile
#include osgDB/ReadFile
#include osg/Camera
#include osg/Light
#include osg/LightSource
#include osg/BoundingSphere
#include osg/BoundingBox
#include osgUtil/Optimizer#include iostream#pragma comment(lib, OpenThreadsd.lib)
#pragma comment(lib, osgd.lib)
#pragma comment(lib, osgDBd.lib)
#pragma comment(lib, osgUtild.lib)
#pragma comment(lib, osgGAd.lib)
#pragma comment(lib, osgViewerd.lib)
#pragma comment(lib, osgTextd.lib)//向场景中添加光源
osg::ref_ptrosg::Group createLight(osg::ref_ptrosg::Node node)
{osg::ref_ptrosg::Group lightRoot new osg::Group();lightRoot-addChild(node);//开启光照osg::ref_ptrosg::StateSet stateset new osg::StateSet();stateset lightRoot-getOrCreateStateSet();stateset-setMode(GL_LIGHTING, osg::StateAttribute::ON);stateset-setMode(GL_LIGHT0, osg::StateAttribute::ON);//计算包围盒osg::BoundingSphere bs;node-computeBound();bs node-getBound();//创建一个Light对象osg::ref_ptrosg::Light light new osg::Light();light-setLightNum(0);//设置方向light-setDirection(osg::Vec3(0.0f, 0.0f, 1.0f));//设置位置light-setPosition(osg::Vec4(bs.center().x(), bs.center().y(), bs.center().z() bs.radius(), 1.0f));//设置环境光的颜色light-setAmbient(osg::Vec4(0.0f, 1.0f, 0.0f, 1.0f));//设置散射光的颜色light-setDiffuse(osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f));//设置恒衰减指数light-setConstantAttenuation(1.0f);//设置线形衰减指数light-setLinearAttenuation(0.0f);//设置二次方衰减指数light-setQuadraticAttenuation(0.0f);//创建光源osg::ref_ptrosg::LightSource lightSource new osg::LightSource();lightSource-setLight(light.get());lightRoot-addChild(lightSource.get());return lightRoot.get();
}int main()
{osg::ref_ptrosgViewer::Viewer viewer new osgViewer::Viewer();osg::ref_ptrosg::Group root new osg::Group();//读取模型osg::ref_ptrosg::Node node osgDB::readNodeFile(cessna.osgt);//向场景中添加光源root-addChild(createLight(node.get()));//优化场景数据osgUtil::Optimizer optimzer;optimzer.optimize(root.get());//方便查看在多边形之间切换以查看三角网viewer-addEventHandler(new osgGA::StateSetManipulator(viewer-getCamera()-getOrCreateStateSet()));viewer-addEventHandler(new osgViewer::StatsHandler());viewer-addEventHandler(new osgViewer::WindowSizeHandler());viewer-setSceneData(root.get());viewer-setUpViewInWindow(600, 600, 800, 600);return viewer-run();
}1.5 聚光灯示例 #include windows.h
#include osgViewer/Viewer
#include osg/Vec3
#include osg/Vec4
#include osg/Quat
#include osg/Matrix
#include osg/ShapeDrawable
#include osg/Geometry
#include osg/Geode
#include osg/Notify
#include osg/MatrixTransform
#include osg/Texture3D
#include osg/Stencil
#include osg/ColorMask
#include osg/GLExtensions
#include osg/Depth
#include osg/AnimationPath
#include osg/Transform
#include osg/Material
#include osg/NodeCallback
#include osg/Depth
#include osg/CullFace
#include osg/TexMat
#include osg/TexGen
#include osg/TexEnv
#include osg/TextureCubeMap
#include osgViewer/ViewerEventHandlers //事件监听
#include osgGA/StateSetManipulator //事件响应类对渲染状态进行控制
#include osgUtil/Simplifier //简化几何体
#include osgDB/WriteFile
#include osgDB/ReadFile
#include osg/Camera
#include osg/Light
#include osg/LightSource
#include osg/BoundingSphere
#include osg/BoundingBox
#include osgUtil/Optimizer
#include osg/TexGenNode
#include osgUtil/DelaunayTriangulator
#include iostream
#include osg/Material
#include osg/CullFace#pragma comment(lib, OpenThreadsd.lib)
#pragma comment(lib, osgd.lib)
#pragma comment(lib, osgDBd.lib)
#pragma comment(lib, osgUtild.lib)
#pragma comment(lib, osgGAd.lib)
#pragma comment(lib, osgViewerd.lib)
#pragma comment(lib, osgTextd.lib)/**创建聚光灯纹理贴图*创建聚光灯状态属性前面的纹理贴图也是渲染状态属性之一*创建聚光灯节点*创建路径动画*创建地形平面变量vertex报错注释掉这个类在场景中将之直接设置为模型牛*创建动画模型路径为前面设置好的路径动画将聚光灯节点添加添加到其中则聚光灯是动态的飞机*创建场景创建动画模型和地形平面地形平面出错此处设为飞机动画模型为聚光灯位置地形平面牛为聚光灯照射的地方将状态属性添加到组节点*则飞机飞到哪个地方即聚光灯在哪里牛的哪个地方就照亮
*/
//创建聚光灯纹理的mipmap贴图
osg::ref_ptrosg::Image createSpotLightImage(const osg::Vec4 centerColour, const osg::Vec4 backgroudColour, unsigned int size, float power)
{//创建Image对象osg::ref_ptrosg::Image image new osg::Image();//动态分配一个size*size大小的imageimage-allocateImage(size, size, 1, GL_RGBA, GL_UNSIGNED_BYTE);//填充image//以中心为原点颜色逐渐向四周衰减float mid (float(size) - 1) * 0.5f;float div 2.0f / float(size);for (unsigned int r 0; r size; r){unsigned char* ptr image-data(0, r, 0);for (unsigned int c 0; c size; c){float dx (float(c) - mid) * div;float dy (float(r) - mid) * div;float r powf(1.0f - sqrtf(dx * dx dy * dy), power);if (r 0.0f)r 0.0f;osg::Vec4 color centerColour * r backgroudColour * (1.0f - r);*ptr (unsigned char)((color[0]) * 255.0f);*ptr (unsigned char)((color[1]) * 255.0f);*ptr (unsigned char)((color[2]) * 255.0f);*ptr (unsigned char)((color[3]) * 255.0f);}}return image.release();
}//创建聚光灯状态属性
osg::ref_ptrosg::StateSet createSpotLightDecoratorState(unsigned int lightNum, unsigned int textureUnit)
{//设置中心的颜色和环境光的颜色osg::Vec4 centerColour(1.0f, 1.0f, 1.0f, 1.0f);osg::Vec4 ambientColour(0.5f, 0.5f, 0.5f, 1.0f);//创建聚光灯纹理osg::ref_ptrosg::Texture2D texture new osg::Texture2D();texture-setImage(createSpotLightImage(centerColour, ambientColour, 64, 1.0));texture-setBorderColor(osg::Vec4(ambientColour));texture-setWrap(osg::Texture::WRAP_S, osg::Texture::CLAMP_TO_BORDER);texture-setWrap(osg::Texture::WRAP_T, osg::Texture::CLAMP_TO_BORDER);texture-setWrap(osg::Texture::WRAP_R, osg::Texture::CLAMP_TO_BORDER);osg::ref_ptrosg::StateSet stateset new osg::StateSet();//开启ID为lightNum的光照stateset-setMode(GL_LIGHT0 lightNum, osg::StateAttribute::ON);//设置自动生成纹理坐标stateset-setTextureMode(textureUnit, GL_TEXTURE_GEN_S, osg::StateAttribute::ON);stateset-setTextureMode(textureUnit, GL_TEXTURE_GEN_T, osg::StateAttribute::ON);stateset-setTextureMode(textureUnit, GL_TEXTURE_GEN_R, osg::StateAttribute::ON);stateset-setTextureMode(textureUnit, GL_TEXTURE_GEN_Q, osg::StateAttribute::ON);//打开纹理单元stateset-setTextureAttributeAndModes(textureUnit, texture.get(), osg::StateAttribute::ON);return stateset.release();
}//创建聚光灯节点
osg::ref_ptrosg::Node createSpotLightNode(const osg::Vec3 position, const osg::Vec3 direction, float angle, unsigned int lightNum, unsigned int textureUnit)
{//创建光源osg::ref_ptrosg::LightSource lightsource new osg::LightSource();osg::ref_ptrosg::Light light lightsource-getLight();light-setLightNum(lightNum);light-setPosition(osg::Vec4(position, 1.0f));light-setAmbient(osg::Vec4(0.00f, 0.00f, 0.05f, 1.0f));light-setDiffuse(osg::Vec4(1.0f, 1.0f, 1.0f, 1.0f));//计算法向量osg::Vec3 up(0.0f, 0.0f, 1.0f);up (direction ^ up) ^ direction;up.normalize();//创建自动生成纹理坐标节点osg::ref_ptrosg::TexGenNode texgenNode new osg::TexGenNode();//关联纹理单元texgenNode-setTextureUnit(textureUnit);//设置纹理坐标生成器osg::ref_ptrosg::TexGen texgen texgenNode-getTexGen();//设置模式为视觉线性texgen-setMode(osg::TexGen::EYE_LINEAR);//从视图中指定参考平面texgen-setPlanesFromMatrix(osg::Matrixd::lookAt(position, position direction, up) * osg::Matrixd::perspective(angle, 1.0, 0.1, 100));osg::ref_ptrosg::Group group new osg::Group();group-addChild(lightsource);group-addChild(texgenNode.get());return group.release();
}
//创建动画路径
osg::ref_ptrosg::AnimationPath createAnimationPath(const osg::Vec3 center, float radius, double looptime)
{osg::ref_ptrosg::AnimationPath animationPath new osg::AnimationPath();animationPath-setLoopMode(osg::AnimationPath::LOOP);int numSamples 40;float yaw 0.0f;float yaw_delta 2.0f * osg::PI / ((float)numSamples - 1.0f);float roll osg::inDegrees(30.0f);double time 0.0f;double time_delta looptime / (double)numSamples;for (int i 0; i numSamples; i){osg::Vec3 position(center osg::Vec3(sinf(yaw) * radius, cosf(yaw) * radius, 0.0f));osg::Quat rotation(osg::Quat(roll, osg::Vec3(0.0, 1.0, 0.0)) * osg::Quat(-(yaw osg::inDegrees(90.0f)), osg::Vec3(0.0, 0.0, 1.0)));animationPath-insert(time, osg::AnimationPath::ControlPoint(position, rotation));yaw yaw_delta;time time_delta;}return animationPath.release();
}//创建动画模型
osg::ref_ptrosg::Node createMovingModel(const osg::Vec3 center, float radius)
{osg::ref_ptrosg::Group model new osg::Group();osg::ref_ptrosg::Node cessna osgDB::readNodeFile(cessna.osg);if (cessna.get()){const osg::BoundingSphere bs cessna-getBound();float size radius / bs.radius() * 0.3f;osg::ref_ptrosg::MatrixTransform positioned new osg::MatrixTransform();positioned-setDataVariance(osg::Object::STATIC);positioned-setMatrix(osg::Matrix::translate(-bs.center()) * osg::Matrix::scale(size, size, size) * osg::Matrix::rotate(osg::inDegrees(180.0f), 0.0f, 0.0f, 2.0f));positioned-addChild(cessna.get());float animationLength 10.0f;osg::ref_ptrosg::AnimationPath animationPath createAnimationPath(center, radius, animationLength);osg::ref_ptrosg::MatrixTransform xform new osg::MatrixTransform();xform-setUpdateCallback(new osg::AnimationPathCallback(animationPath, 0.0f, 2.0));xform-addChild(positioned);//添加聚光灯节点xform-addChild(createSpotLightNode(osg::Vec3(0.0f, 0.0f, 0.0f), osg::Vec3(0.0f, 1.0f, -1.0f), 60.0f, 0, 1));model-addChild(xform.get());}return model.release();
}//创建地形平面
osg::ref_ptrosg::Node createBase()
{//创建顶点数组osg::ref_ptrosg::Vec3Array coords new osg::Vec3Array();//添加顶点数据int nMin -5;int nMax 10;for (int i -100; i 100; i 10){if (i -100 i 0){nMin -6;nMax 3;}else if (i 0 i 50){nMin -3;nMax 7;}else if (i 50 i 100){nMin 5;nMax 3;}for (int j -100; j 100; j 10){float nZ (float)(nMin, nMax) / 2;osg::Vec3 vertex(i, j, nZ);coords-push_back(vertex);}}//创建颜色数组osg::ref_ptrosg::Vec4Array color new osg::Vec4Array();//添加颜色数据 for (unsigned int i 0; i 400; i){int nR rand() % 10 2;color-push_back(osg::Vec4(0.0f, (double)nR / 10.0, 0.0f, 0.5f));}//创建Delaunay三角网对象osg::ref_ptrosgUtil::DelaunayTriangulator dt new osgUtil::DelaunayTriangulator(coords.get());//生成三角网dt-triangulate();//创建几何体osg::ref_ptrosg::Geometry pGeometry new osg::Geometry();//设置顶点数组pGeometry-setVertexArray(coords.get());osg::ref_ptrosg::Image sImagePath osgDB::readImageFile(Terrain.png);if (sImagePath.get()){osg::ref_ptrosg::Texture2D texture2D new osg::Texture2D;texture2D-setImage(sImagePath.get());// 绑定纹理后释放内部的ref_ptrImage删除image图像texture2D-setUnRefImageDataAfterApply(true);// 建立纹理顶点osg::ref_ptrosg::Vec2Array pVec2Array new osg::Vec2Array;for (int i -100; i 100; i 10){for (int j -100; j 100; j 10){osg::Vec2 textCoord(0.0, 0.0);textCoord.x() (double)(j 100.0) / 200.0;textCoord.y() (double)(i 100.0) / 200.0;pVec2Array-push_back(textCoord);}}// Texture类关联到渲染状态StateSetosg::ref_ptrosg::StateSet pStateSet pGeometry-getOrCreateStateSet();// 将纹理关联给StateSet纹理单元0、osg::StateAttribute::OFF关闭纹理pStateSet-setTextureAttributeAndModes(0, texture2D.get(), osg::StateAttribute::ON);pGeometry-setTexCoordArray(0, pVec2Array.get());// 建立法线数组normalosg::ref_ptrosg::Vec3Array pVec3ArrayNormal new osg::Vec3Array;pGeometry-setNormalArray(pVec3ArrayNormal.get());pGeometry-setNormalBinding(osg::Geometry::BIND_OVERALL);//垂直于Z轴负方向pVec3ArrayNormal-push_back(osg::Vec3(0.0, 0.0, 1.0));pGeometry-setStateSet(pStateSet);}else{//设置颜色数组pGeometry-setColorArray(color.get());//设置颜色的绑定方式为单个顶点pGeometry-setColorBinding(osg::Geometry::BIND_PER_VERTEX);}//添加到绘图基元pGeometry-addPrimitiveSet(dt-getTriangles());osg::ref_ptr osg::Geode pGNode new osg::Geode;pGNode-addChild(pGeometry);return pGNode.release();}//创建场景
osg::ref_ptrosg::Node createModel()
{osg::Vec3 center(0.0f, 0.0f, 0.0f);float radius 60.0f;//创建动画模型osg::ref_ptrosg::Node shadower createMovingModel(center, radius * 0.5f);//创建地形平面osg::ref_ptrosg::Node shadowed osgDB::readNodeFile(cow.osg);//osg::ref_ptrosg::Node shadowed createBase(center - osg::Vec3(0.0f, 0.0f, radius * 0.1), radius);//创建场景组节点osg::ref_ptrosg::Group root new osg::Group();//设置状态属性root-setStateSet(createSpotLightDecoratorState(0, 1));//添加子节点root-addChild(shadower.get());root-addChild(shadowed.get());return root.release();
}int main()
{osg::ref_ptrosgViewer::Viewer viewer new osgViewer::Viewer();osg::ref_ptrosg::Group root new osg::Group();//添加场景root-addChild(createModel());//优化场景数据osgUtil::Optimizer optimzer;optimzer.optimize(root.get());//方便查看在多边形之间切换以查看三角网viewer-addEventHandler(new osgGA::StateSetManipulator(viewer-getCamera()-getOrCreateStateSet()));viewer-addEventHandler(new osgViewer::StatsHandler());viewer-addEventHandler(new osgViewer::WindowSizeHandler());viewer-setSceneData(root.get());viewer-setUpViewInWindow(600, 600, 800, 600);return viewer-run();return 0;
}2、OSG材质
2.1 材质类 OSG 材质类osg::Material继承自 osg::StateAttribute 类。osg::Material 封装了 OpenGL 的 glMaterial()和 glColorMaterial()指令的函数功能。
在场景中设置节点的材质属性首先要创建一个 osg::Material 对象然后设置颜色和其他参数再关联到场景图形的 StateSet 中如下面的代码
osg::StateSet* state node-getOrCreateStateSet();
osg::ref_ptrosg::Material mat new osg::Material;
state-setAttribute( mat.get() );osg::Material 类包含的主要属性如下
bool _ambientFrontAndBack; //前面与后面的环境光
Vec4 _ambientFront; //前面的环境光 r、g、b、w
Vec4 _ambientBack; //后面的环境光r、g、b、w
bool _diffuseFrontAndBack; //前面与后面的漫射光
Vec4 _diffuseFront; //前面的漫射光r、g、b、w
Vec4 _diffuseBack; //后面的漫射光r、g、b、w
bool _specularFrontAndBack; //前面与后面的镜面光
Vec4 _specularFront; //前面的镜面光r、g、b、w
Vec4 _specularBack; //后面的镜面光r、g、b、w
bool _emissionFrontAndBack; //前面与后面的发射光emission
Vec4 _emissionFront; //前面的 emissionr、g、b、w
Vec4 _emissionBack; //后面的 emissionr、g、b、w
bool _shininessFrontAndBack; //前面与后面的发光shininess
float _shininessFront; //前面的 shininess
float _shininessBack; //后面的 shininess注意shininess 是一个在 0128.0 之间的值值越大亮点越小、越亮。
OSG 材质的面如下
enum Face
{
FRONT GL_FRONT, //前
BACK GL_BACK, //后
FRONT_AND_BACK GL_FRONT_AND_BACK //前、后
};OSG 材质的颜色模式如下
enum ColorMode
{
AMBIENT GL_AMBIENT, //环境光颜色
DIFFUSE GL_DIFFUSE, //漫射光颜色
SPECULAR GL_SPECULAR, //镜面光颜色
EMISSION GL_EMISSION, //发射光颜色
AMBIENT_AND_DIFFUSE GL_AMBIENT_AND_DIFFUSE, //环境与漫射光颜色
OFF //关闭模式
};在进行很多 OpenGL 的操作时直接设置材质属性可能会过于耗费资源而 OSG 提供了一种颜色跟踪材质的高效方法操作比直接修改材质属性的效率更高颜色跟踪材质color material允许用户程序通过改变当前颜色的方法自动改变某一特定的材质属性。在许多情形下这一操作比直接修改材质属性的效率要高能加强光照场景和无光照场景的联系并满足应用程序对材质的需要。 允许颜色跟踪材质的特性需要调用 setColorMode()方法。osg::Material 类为之定义了枚举量AMBIENT、DIFFUSE、SPECULAR、EMISSION、AMBIENT_AND_DIFFUSE 以及 OFF。默认情况下颜色跟踪模式被设置为 OFF颜色跟踪材质被禁止。如果用户程序设置颜色跟踪模式为其他的值那么 OSG 将为特定的材质属性开启颜色跟踪材质特性此时主颜色的改变将会改变相应的材质属性。 注意根据颜色跟踪模式的取值不同Material 类会自动允许或禁止GL_COLOR_MATERIAL。因此用户程序不需要调用 setAttributeAndModes()来允许或禁止相关的模式值。
2.2 材质类示例 #include windows.h
#include osgViewer/Viewer
#include osg/Vec3
#include osg/Vec4
#include osg/Quat
#include osg/Matrix
#include osg/ShapeDrawable
#include osg/Geometry
#include osg/Geode
#include osg/Notify
#include osg/MatrixTransform
#include osg/Texture3D
#include osg/Stencil
#include osg/ColorMask
#include osg/GLExtensions
#include osg/Depth
#include osg/AnimationPath
#include osg/Transform
#include osg/Material
#include osg/NodeCallback
#include osg/Depth
#include osg/CullFace
#include osg/TexMat
#include osg/TexGen
#include osg/TexEnv
#include osg/TextureCubeMap
#include osgViewer/ViewerEventHandlers //事件监听
#include osgGA/StateSetManipulator //事件响应类对渲染状态进行控制
#include osgUtil/Simplifier //简化几何体
#include osgDB/WriteFile
#include osgDB/ReadFile
#include osg/Camera
#include osg/Light
#include osg/LightSource
#include osg/BoundingSphere
#include osg/BoundingBox
#include osgUtil/Optimizer
#include osg/TexGenNode
#include osgUtil/DelaunayTriangulator
#include iostream
#include osg/Material
#include osg/CullFace#pragma comment(lib, OpenThreadsd.lib)
#pragma comment(lib, osgd.lib)
#pragma comment(lib, osgDBd.lib)
#pragma comment(lib, osgUtild.lib)
#pragma comment(lib, osgGAd.lib)
#pragma comment(lib, osgViewerd.lib)
#pragma comment(lib, osgTextd.lib)//创建一个四边形节点
osg::ref_ptrosg::Node createNode()
{osg::ref_ptrosg::Geode geode new osg::Geode();osg::ref_ptrosg::Geometry geom new osg::Geometry();//设置顶点osg::ref_ptrosg::Vec3Array vc new osg::Vec3Array();vc-push_back(osg::Vec3(0.0f, 0.0f, 0.0f));vc-push_back(osg::Vec3(1.0f, 0.0f, 0.0f));vc-push_back(osg::Vec3(1.0f, 0.0f, 1.0f));vc-push_back(osg::Vec3(0.0f, 0.0f, 1.0f));geom-setVertexArray(vc.get());//设置纹理坐标osg::ref_ptrosg::Vec2Array vt new osg::Vec2Array();vt-push_back(osg::Vec2(0.0f, 0.0f));vt-push_back(osg::Vec2(1.0f, 0.0f));vt-push_back(osg::Vec2(1.0f, 1.0f));vt-push_back(osg::Vec2(0.0f, 1.0f));geom-setTexCoordArray(0, vt.get());//设置法线osg::ref_ptrosg::Vec3Array nc new osg::Vec3Array();nc-push_back(osg::Vec3(0.0f, -1.0f, 0.0f));geom-setNormalArray(nc.get());geom-setNormalBinding(osg::Geometry::BIND_OVERALL);//添加图元geom-addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS, 0, 4));//绘制geode-addDrawable(geom.get());return geode.get();
}int main()
{osg::ref_ptrosgViewer::Viewer viewer new osgViewer::Viewer();osg::ref_ptrosg::Group root new osg::Group();osg::ref_ptrosg::Node node createNode();//得到状态属性osg::ref_ptrosg::StateSet stateset new osg::StateSet();stateset node-getOrCreateStateSet();//创建材质对象osg::ref_ptrosg::Material mat new osg::Material();//设置正面散射颜色mat-setDiffuse(osg::Material::FRONT, osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f));//设置正面镜面颜色mat-setSpecular(osg::Material::FRONT, osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f));//设置正面指数mat-setShininess(osg::Material::FRONT, 90.0f);stateset-setAttribute(mat.get());//设置背面剔除osg::ref_ptrosg::CullFace cullface new osg::CullFace(osg::CullFace::BACK);stateset-setAttribute(cullface.get());stateset-setMode(GL_CULL_FACE, osg::StateAttribute::OFF);root-addChild(node.get());//优化场景数据osgUtil::Optimizer optimzer;optimzer.optimize(root.get());//方便查看在多边形之间切换以查看三角网viewer-addEventHandler(new osgGA::StateSetManipulator(viewer-getCamera()-getOrCreateStateSet()));viewer-addEventHandler(new osgViewer::StatsHandler());viewer-addEventHandler(new osgViewer::WindowSizeHandler());viewer-setSceneData(root.get());viewer-setUpViewInWindow(600, 600, 800, 600);return viewer-run();
}
