【OSG学习笔记】Day 16: 骨骼动画与蒙皮（osgAnimation）

_李小白2025-06-10 21:27

骨骼动画基础

骨骼动画是 3D 计算机图形中常用的技术，它通过以下两个主要组件实现角色动画。

  • 骨骼系统 (Skeleton)：由层级结构的骨头组成，类似于人体骨骼
  • 蒙皮 (Mesh Skinning)：将模型网格顶点绑定到骨骼上，使骨骼移动时带动网格变形

在 OSG 中，这些功能主要由osgAnimation库提供支持。

当然可以！以下是 Day 16：骨骼动画与蒙皮（osgAnimation） 中的"核心知识点"部分，以标准 Markdown (.md) 格式呈现：

核心知识点

类名 作用
osgAnimation::AnimationManagerBase 动画管理器接口，定义了动画更新的基本行为
osgAnimation::BasicAnimationManager 基础动画管理器实现类，用于管理和播放多个动画
osgAnimation::RigGeometry 蒙皮网格数据结构，支持骨骼影响顶点的变形计算
osgAnimation::AnimationPathCallback 动画路径回调，可用于控制骨骼或模型沿特定路径运动
osgDB::readNodeFile() 加载模型文件（支持 OSGT 等格式），自动解析动画和骨骼信息

OSGT 格式

格式 骨骼支持 动画保留 OSG 兼容性
.osgt ✅ 完整 ✅ 完整 ⭐⭐⭐⭐⭐（原生支持，推荐使用）
.dae ✅ 完整 ✅ 完整 ⭐⭐⭐⭐（需 Collada 插件）
.fbx ❌ 不支持 ❌ 不支持 不可直接读取
  • .osgt：OSG 的二进制序列化格式，支持完整的骨骼与动画数据，加载速度快，兼容性最好。
  • .dae（Collada） ：开放的 XML 格式，广泛用于三维模型交换，支持骨骼和动画，但需要 OSG 的 osgdb_collada 插件。
  • .fbx ：Autodesk 的私有格式，功能强大，但 OpenSceneGraph 默认不支持 FBX ，需要借助第三方插件（如 OpenSceneGraph-FBX）才能加载。

实战

实战1

通过代码自动生成动画效果。

animation.cpp

cpp 复制代码 
#include <osgViewer/Viewer>
#include <osg/Group>
#include <osg/Geode>
#include <osg/ShapeDrawable>
#include <osg/MatrixTransform>
#include <osgAnimation/BasicAnimationManager>
#include <osgAnimation/UpdateMatrixTransform>
#include <osgAnimation/Animation>
#include <osgAnimation/Channel>
#include <osgGA/TrackballManipulator>
#include <osg/Material>
#include <osgDB/Registry>
#include <osg/Notify>
#include <iostream>

// 创建骨骼节点
osg::MatrixTransform* createBone(const std::string& name, float length, const osg::Vec4& color) {
    osg::ref_ptr<osg::MatrixTransform> bone = new osg::MatrixTransform;
    bone->setName(name);
    
    // 创建骨骼可视化（圆柱体）
    osg::ref_ptr<osg::Cylinder> cylinder = new osg::Cylinder(osg::Vec3(0, 0, length/2), 0.1f, length);
    osg::ref_ptr<osg::ShapeDrawable> drawable = new osg::ShapeDrawable(cylinder);
    
    // 设置颜色
    osg::ref_ptr<osg::Material> material = new osg::Material;
    material->setDiffuse(osg::Material::FRONT, osg::Vec4(color));
    drawable->getOrCreateStateSet()->setAttributeAndModes(material.get());
    
    // 添加关节球
    osg::ref_ptr<osg::Sphere> jointSphere = new osg::Sphere(osg::Vec3(0, 0, 0), 0.15f);
    osg::ref_ptr<osg::ShapeDrawable> jointDrawable = new osg::ShapeDrawable(jointSphere);
    jointDrawable->setColor(osg::Vec4(1.0f, 1.0f, 0.0f, 1.0f));
    
    osg::ref_ptr<osg::Geode> geode = new osg::Geode;
    geode->addDrawable(drawable.get());
    geode->addDrawable(jointDrawable.get());
    
    bone->addChild(geode.get());
    
    return bone.release();
}

// 在main函数中添加临时测试动画
class SimpleRotationCallback : public osg::NodeCallback {
public:
    virtual void operator()(osg::Node* node, osg::NodeVisitor* nv) {
        static double start = osg::Timer::instance()->time_s();
        double t = osg::Timer::instance()->time_s() - start;
        float angle = sin(t) * 1.0f; // 摆动幅度
        
        osg::MatrixTransform* mt = dynamic_cast<osg::MatrixTransform*>(node);
        if (mt) {
            mt->setMatrix(osg::Matrix::rotate(angle, osg::Vec3(0,1,0)));
        }
        
        traverse(node, nv);
    }
};


// 创建动画
osgAnimation::Animation* createArmAnimation() {
    osg::ref_ptr<osgAnimation::Animation> animation = new osgAnimation::Animation;
    animation->setName("ArmAnimation");
    
    // 创建肩关节动画通道
    osg::ref_ptr<osgAnimation::QuatSphericalLinearChannel> shoulderChannel = 
        new osgAnimation::QuatSphericalLinearChannel;
    shoulderChannel->setName("rotation");
    shoulderChannel->setTargetName("Shoulder");
    
    osgAnimation::QuatKeyframeContainer* shoulderKeyframes = shoulderChannel->getOrCreateSampler()->getOrCreateKeyframeContainer();
    shoulderKeyframes->push_back(osgAnimation::QuatKeyframe(0.0, osg::Quat(0, osg::Vec3(0,1,0))));
    shoulderKeyframes->push_back(osgAnimation::QuatKeyframe(2.0, osg::Quat(osg::PI/4, osg::Vec3(0,1,0))));
    shoulderKeyframes->push_back(osgAnimation::QuatKeyframe(4.0, osg::Quat(-osg::PI/4, osg::Vec3(0,1,0))));
    shoulderKeyframes->push_back(osgAnimation::QuatKeyframe(6.0, osg::Quat(0, osg::Vec3(0,1,0))));
    
    // 创建肘关节动画通道
    osg::ref_ptr<osgAnimation::QuatSphericalLinearChannel> elbowChannel = 
        new osgAnimation::QuatSphericalLinearChannel;
    elbowChannel->setName("rotation");
    elbowChannel->setTargetName("Elbow");
    
    osgAnimation::QuatKeyframeContainer* elbowKeyframes = elbowChannel->getOrCreateSampler()->getOrCreateKeyframeContainer();
    elbowKeyframes->push_back(osgAnimation::QuatKeyframe(0.0, osg::Quat(0, osg::Vec3(0,1,0))));
    elbowKeyframes->push_back(osgAnimation::QuatKeyframe(1.0, osg::Quat(osg::PI/2, osg::Vec3(0,1,0))));
    elbowKeyframes->push_back(osgAnimation::QuatKeyframe(2.0, osg::Quat(0, osg::Vec3(0,1,0))));
    elbowKeyframes->push_back(osgAnimation::QuatKeyframe(3.0, osg::Quat(osg::PI/2, osg::Vec3(0,1,0))));
    elbowKeyframes->push_back(osgAnimation::QuatKeyframe(4.0, osg::Quat(0, osg::Vec3(0,1,0))));
    elbowKeyframes->push_back(osgAnimation::QuatKeyframe(6.0, osg::Quat(0, osg::Vec3(0,1,0))));
    
    // 创建腕关节动画通道
    osg::ref_ptr<osgAnimation::QuatSphericalLinearChannel> wristChannel = 
        new osgAnimation::QuatSphericalLinearChannel;
    wristChannel->setName("rotation");
    wristChannel->setTargetName("Wrist");
    
    osgAnimation::QuatKeyframeContainer* wristKeyframes = wristChannel->getOrCreateSampler()->getOrCreateKeyframeContainer();
    wristKeyframes->push_back(osgAnimation::QuatKeyframe(0.0, osg::Quat(0, osg::Vec3(1,0,0))));
    wristKeyframes->push_back(osgAnimation::QuatKeyframe(1.5, osg::Quat(osg::PI/3, osg::Vec3(1,0,0))));
    wristKeyframes->push_back(osgAnimation::QuatKeyframe(3.0, osg::Quat(-osg::PI/3, osg::Vec3(1,0,0))));
    wristKeyframes->push_back(osgAnimation::QuatKeyframe(4.5, osg::Quat(osg::PI/3, osg::Vec3(1,0,0))));
    wristKeyframes->push_back(osgAnimation::QuatKeyframe(6.0, osg::Quat(0, osg::Vec3(1,0,0))));
    
    animation->addChannel(shoulderChannel.get());
    animation->addChannel(elbowChannel.get());
    animation->addChannel(wristChannel.get());
    
    animation->setPlayMode(osgAnimation::Animation::LOOP);
    animation->setDuration(6.0);
    
    return animation.release();
}

// 创建手臂模型
osg::Group* createArm() {
    osg::ref_ptr<osg::Group> root = new osg::Group;
    
    // 创建骨骼层级结构
    osg::ref_ptr<osg::MatrixTransform> shoulder = createBone("Shoulder", 2.0f, osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f));
    osg::ref_ptr<osg::MatrixTransform> elbow = createBone("Elbow", 1.5f, osg::Vec4(0.0f, 1.0f, 0.0f, 1.0f));
    osg::ref_ptr<osg::MatrixTransform> wrist = createBone("Wrist", 1.0f, osg::Vec4(0.0f, 0.0f, 1.0f, 1.0f));
    
    // 设置骨骼初始位置
    shoulder->setMatrix(osg::Matrix::translate(0, 0, 0));
    elbow->setMatrix(osg::Matrix::translate(0, 0, 2.0f));
    wrist->setMatrix(osg::Matrix::translate(0, 0, 1.5f));
    
    // 构建层级关系
    shoulder->addChild(elbow);
    elbow->addChild(wrist);
    
    // 添加动画更新回调
    shoulder->setUpdateCallback(new SimpleRotationCallback);
    elbow->setUpdateCallback(new osgAnimation::UpdateMatrixTransform("Elbow"));
    wrist->setUpdateCallback(new osgAnimation::UpdateMatrixTransform("Wrist"));
    
    // 创建手爪模型
    osg::ref_ptr<osg::Geode> handGeode = new osg::Geode;
    osg::ref_ptr<osg::Box> leftFinger = new osg::Box(osg::Vec3(-0.2f, 0, 0.5f), 0.1f, 0.1f, 1.0f);
    osg::ref_ptr<osg::Box> rightFinger = new osg::Box(osg::Vec3(0.2f, 0, 0.5f), 0.1f, 0.1f, 1.0f);
    osg::ref_ptr<osg::ShapeDrawable> leftDrawable = new osg::ShapeDrawable(leftFinger);
    osg::ref_ptr<osg::ShapeDrawable> rightDrawable = new osg::ShapeDrawable(rightFinger);
    leftDrawable->setColor(osg::Vec4(0.8f, 0.8f, 0.8f, 1.0f));
    rightDrawable->setColor(osg::Vec4(0.8f, 0.8f, 0.8f, 1.0f));
    handGeode->addDrawable(leftDrawable);
    handGeode->addDrawable(rightDrawable);
    wrist->addChild(handGeode);
    
    root->addChild(shoulder);
    
    // 创建底座
    osg::ref_ptr<osg::Geode> baseGeode = new osg::Geode;
    osg::ref_ptr<osg::Cylinder> baseCylinder = new osg::Cylinder(osg::Vec3(0,0,-0.5f), 1.0f, 0.5f);
    osg::ref_ptr<osg::ShapeDrawable> baseDrawable = new osg::ShapeDrawable(baseCylinder);
    baseDrawable->setColor(osg::Vec4(0.5f, 0.5f, 0.5f, 1.0f));
    baseGeode->addDrawable(baseDrawable);
    root->addChild(baseGeode);
    
    return root.release();
}

int main() {
    // 设置调试输出级别
    osg::setNotifyLevel(osg::NOTICE);
    
    // 创建Viewer
    osgViewer::Viewer viewer;
    
    // 创建主场景组
    osg::ref_ptr<osg::Group> root = new osg::Group;
    
    // 添加手臂模型
    root->addChild(createArm());
    
    // 创建动画管理器
    osg::ref_ptr<osgAnimation::BasicAnimationManager> animManager = new osgAnimation::BasicAnimationManager;
    
    // 将动画管理器作为场景图的更新回调
    root->setUpdateCallback(animManager);
    
    // 添加动画
    osgAnimation::Animation* anim = createArmAnimation();
    animManager->registerAnimation(anim);
    animManager->playAnimation(anim);
    
    // 输出调试信息
    std::cout << "动画管理器状态: " << (animManager.valid() ? "有效" : "无效") << std::endl;
    std::cout << "已注册动画数量: " << animManager->getAnimationList().size() << std::endl;
    if (animManager->getAnimationList().size() > 0) {
        std::cout << "正在播放动画: " << animManager->getAnimationList()[0]->getName() << std::endl;
    }
    
    viewer.setSceneData(root);
    viewer.setCameraManipulator(new osgGA::TrackballManipulator);
    
    // 设置初始视角
    viewer.getCameraManipulator()->setHomePosition(
        osg::Vec3(0, -10, 5), // 眼睛位置
        osg::Vec3(0, 0, 2),   // 中心位置
        osg::Vec3(0, 0, 1)    // 上方向
    );
    viewer.home(); // 应用初始视角设置
    
    return viewer.run();
}
运行效果
加载osgt文件

animationOsgt.cpp

cpp 复制代码 
#include <osgDB/ReadFile>
#include <osgViewer/Viewer>
#include <osgGA/TrackballManipulator>
#include <osgAnimation/BasicAnimationManager>

int main() {
    // 1. 加载模型
    osg::ref_ptr<osg::Node> model = osgDB::readNodeFile("../dumptruck.osgt");
    if (!model) return 1;

    // 2. 获取动画管理器
    osgAnimation::BasicAnimationManager* animManager = 
        dynamic_cast<osgAnimation::BasicAnimationManager*>(model->getUpdateCallback());
    
    if (animManager && !animManager->getAnimationList().empty()) {
        // 3. 正确播放动画（两种解决方案）：
        if (animManager) {
            const osgAnimation::AnimationList& animList = animManager->getAnimationList();
            if (!animList.empty()) {
            // 打印所有动画信息
            for (const auto& anim : animList) {
                std::cout << "Found animation: " << anim->getName() 
                          << " (" << anim->getDuration() << "s)\n";
            }
        
            // 播放第一个动画
            animManager->playAnimation(animList[0]);
            } else {
                std::cerr << "Warning: No animations found in the model" << std::endl;
            }
        } else {
            std::cerr << "Error: No AnimationManager found" << std::endl;
        }
    
    }

    // 4. 设置查看器
    osgViewer::Viewer viewer;
    viewer.setSceneData(model);
    viewer.setCameraManipulator(new osgGA::TrackballManipulator());
    return viewer.run();
}
运行效果

本章可能会和自己的osg版本有关系，会有一些报错。耐心解决。_

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