Qt opengl assimp加载骨骼动画

加载骨骼动画的步骤可以分为以下几个：

1. 使用Assimp库加载包含骨骼动画的模型文件，并获取动画相关的信息，比如骨骼数、关键帧数、每个关键帧的变换信息等。

2. 创建OpenGL的顶点数组对象（VAO）和顶点缓冲对象（VBO），以及索引缓冲对象（IBO）。

3. 在顶点着色器中定义顶点属性，包括位置、法线、纹理坐标和骨骼权重。

4. 在顶点着色器中定义uniform变量，用于传递骨骼变换矩阵。

5. 在渲染循环中，计算每个关键帧的骨骼变换矩阵，并将其传递给顶点着色器中的uniform变量。

6. 在顶点着色器中，根据骨骼权重计算每个顶点的最终位置和法线。

7. 使用IBO和VAO绘制模型。

下面是一个简单的实现示例：

// 加载模型
Assimp::Importer importer;
const aiScene* scene = importer.ReadFile(filename, aiProcess_Triangulate | aiProcess_FlipUVs | aiProcess_CalcTangentSpace | aiProcess_LimitBoneWeights);
if (!scene || scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE || !scene->mRootNode) {
    // 加载失败
}

// 获取动画相关信息
const aiAnimation* animation = scene->mAnimations[0];
int numBones = animation->mNumChannels;

// 创建VAO、VBO和IBO
GLuint vao, vbo, ibo;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * vertices.size(), &vertices[0], GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, position));
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, normal));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, texCoord));
glEnableVertexAttribArray(3);
glVertexAttribPointer(3, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, boneWeights));
glEnableVertexAttribArray(4);
glVertexAttribIPointer(4, 4, GL_INT, sizeof(Vertex), (void*)offsetof(Vertex, boneIndices));
glGenBuffers(1, &ibo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * indices.size(), &indices[0], GL_STATIC_DRAW);

// 在顶点着色器中定义顶点属性和uniform变量
const char* vertexShaderSource =
    "#version 330 core\n"
    "layout (location = 0) in vec3 aPos;\n"
    "layout (location = 1) in vec3 aNormal;\n"
    "layout (location = 2) in vec2 aTexCoord;\n"
    "layout (location = 3) in vec4 aBoneWeights;\n"
    "layout (location = 4) in int aBoneIndices[4];\n"
    "uniform mat4 uBoneMatrices[" + std::to_string(numBones) + "];\n"
    "out vec3 vNormal;\n"
    "out vec2 vTexCoord;\n"
    "void main()\n"
    "{\n"
    "   vec4 position = vec4(aPos, 1.0);\n"
    "   vec4 normal = vec4(aNormal, 0.0);\n"
    "   for (int i = 0; i < 4; i++) {\n"
    "       position = uBoneMatrices[aBoneIndices[i]] * vec4(aPos, 1.0) * aBoneWeights[i] + position;\n"
    "       normal = uBoneMatrices[aBoneIndices[i]] * vec4(aNormal, 0.0) * aBoneWeights[i] + normal;\n"
    "   }\n"
    "   gl_Position = projection * view * model * position;\n"
    "   vNormal = normalize(normal.xyz);\n"
    "   vTexCoord = aTexCoord;\n"
    "}\n";

// 在渲染循环中计算骨骼变换矩阵，并传递给顶点着色器
for (int i = 0; i < numBones; i++) {
    aiNodeAnimation* nodeAnim = animation->mChannels[i];
    std::string boneName = nodeAnim->mNodeName.C_Str();
    aiMatrix4x4 boneOffset = m_BoneOffsets[boneName];
    aiMatrix4x4 boneTransform = m_AnimatedTransforms[boneName];
    aiMatrix4x4 globalTransform = m_GlobalInverseTransform * boneTransform * boneOffset;
    glUniformMatrix4fv(glGetUniformLocation(shaderProgram, ("uBoneMatrices[" + std::to_string(i) + "]").c_str()), 1, GL_TRUE, (float*)&globalTransform);
}

// 在顶点着色器中根据骨骼权重计算每个顶点的最终位置和法线
const char* fragmentShaderSource =
    "#version 330 core\n"
    "in vec3 vNormal;\n"
    "in vec2 vTexCoord;\n"
    "out vec4 FragColor;\n"
    "void main()\n"
    "{\n"
    "   vec3 diffuse = texture(diffuseMap, vTexCoord).rgb;\n"
    "   vec3 normal = normalize(vNormal);\n"
    "   FragColor = vec4(diffuse * (0.5 + 0.5 * max(dot(normal, lightDir), 0.0)), 1.0);\n"
    "}\n";