问基于VAO/VBO的OpenGL模型/纹理绘制

EN

int Mesh::LoadGLTextures(const aiScene* scene){
  if (scene->HasTextures()) return -1; //yes this is correct
  /* getTexture Filenames and Numb of Textures */
  for (unsigned int m = 0; m<scene->mNumMaterials; m++){
    int texIndex = 0;

    aiReturn texFound;
    aiString path;  // filename

    while ((texFound = scene->mMaterials[m]->GetTexture(aiTextureType_DIFFUSE, texIndex, &path)) == AI_SUCCESS){
        textureIdMap[path.data] = NULL; //fill map with textures, pointers still NULL yet
        texIndex++;
    }
  }

  int numTextures = textureIdMap.size();
  /* create and fill array with GL texture ids */
  GLuint* textureIds = new GLuint[numTextures];

  /* get iterator */
  std::map<std::string, GLuint>::iterator itr = textureIdMap.begin();

  std::string basepath = getBasePath(path);

  ALLEGRO_BITMAP *image;
  for (int i = 0; i<numTextures; i++){
    std::string filename = (*itr).first;  // get filename
    (*itr).second = textureIds[i];    // save texture id for filename in map
    itr++;                                // next texture

    std::string fileloc = basepath + filename;  /* Loading of image */
    image = al_load_bitmap(fileloc.c_str());

    if (image) /* If no error occured: */{
        GLuint texId = al_get_opengl_texture(image);

        //glGenTextures(numTextures, &textureIds[i]); /* Texture name generation */
        glBindTexture(GL_TEXTURE_2D, texId); /* Binding of texture name */
        //redefine standard texture values
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); /* We will use linear
                                                                          interpolation for magnification filter */
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); /* We will use linear
                                                                          interpolation for minifying filter */
        textureIdMap[filename] = texId;
    } else {
        /* Error occured */
        std::cout << "Couldn't load Image: " << fileloc.c_str() << "\n";
    }
  }

  //Cleanup
  delete[] textureIds;

  //return success
  return true;
}

void Mesh::genVAOsAndUniformBuffer(const aiScene *sc) {
  struct MyMesh aMesh;
  struct MyMaterial aMat;
  GLuint buffer;

  // For each mesh
  for (unsigned int n = 0; n < sc->mNumMeshes; ++n){
    const aiMesh* mesh = sc->mMeshes[n];

    // create array with faces
    // have to convert from Assimp format to array
    unsigned int *faceArray;
    faceArray = (unsigned int *)malloc(sizeof(unsigned int) * mesh->mNumFaces * 3);
    unsigned int faceIndex = 0;

    for (unsigned int t = 0; t < mesh->mNumFaces; ++t) {
        const aiFace* face = &mesh->mFaces[t];

        memcpy(&faceArray[faceIndex], face->mIndices, 3 * sizeof(unsigned int));
        faceIndex += 3;
    }
    aMesh.numFaces = sc->mMeshes[n]->mNumFaces;

    // generate Vertex Array for mesh
    glGenVertexArrays(1, &(aMesh.vao));
    glBindVertexArray(aMesh.vao);

    // buffer for faces
    glGenBuffers(1, &buffer);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * mesh->mNumFaces * 3, faceArray, GL_STATIC_DRAW);

    // buffer for vertex positions
    if (mesh->HasPositions()) {
        glGenBuffers(1, &buffer);
        glBindBuffer(GL_ARRAY_BUFFER, buffer);
        glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 3 * mesh->mNumVertices, mesh->mVertices, GL_STATIC_DRAW);
        glEnableVertexAttribArray(vertexLoc);
        glVertexAttribPointer(vertexLoc, 3, GL_FLOAT, 0, 0, 0);
    }

    // buffer for vertex normals
    if (mesh->HasNormals()) {
        glGenBuffers(1, &buffer);
        glBindBuffer(GL_ARRAY_BUFFER, buffer);
        glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 3 * mesh->mNumVertices, mesh->mNormals, GL_STATIC_DRAW);
        glEnableVertexAttribArray(normalLoc);
        glVertexAttribPointer(normalLoc, 3, GL_FLOAT, 0, 0, 0);
    }

    // buffer for vertex texture coordinates
    if (mesh->HasTextureCoords(0)) {
        float *texCoords = (float *)malloc(sizeof(float) * 2 * mesh->mNumVertices);
        for (unsigned int k = 0; k < mesh->mNumVertices; ++k) {
            texCoords[k * 2] = mesh->mTextureCoords[0][k].x;
            texCoords[k * 2 + 1] = mesh->mTextureCoords[0][k].y;
        }

        glGenBuffers(1, &buffer);
        glEnableVertexAttribArray(texCoordLoc);
        glBindBuffer(GL_ARRAY_BUFFER, buffer);

        glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 2 * mesh->mNumVertices, texCoords, GL_STATIC_DRAW);
        glVertexAttribPointer(texCoordLoc, 2, GL_FLOAT, GL_FALSE, 0, 0);
    }

    // unbind buffers
    glBindVertexArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

    // create material uniform buffer
    aiMaterial *mtl = sc->mMaterials[mesh->mMaterialIndex];

    aiString texPath;   //contains filename of texture
    if (AI_SUCCESS == mtl->GetTexture(aiTextureType_DIFFUSE, 0, &texPath)){
        //bind texture
        unsigned int texId = textureIdMap[texPath.data];
        aMesh.texIndex = texId;
        aMat.texCount = 1;
    } else {
        aMat.texCount = 0;
    }

    float c[4];
    set_float4(c, 0.8f, 0.8f, 0.8f, 1.0f);
    aiColor4D diffuse;
    if (AI_SUCCESS == aiGetMaterialColor(mtl, AI_MATKEY_COLOR_DIFFUSE, &diffuse))
        color4_to_float4(&diffuse, c);
    memcpy(aMat.diffuse, c, sizeof(c));

    set_float4(c, 0.2f, 0.2f, 0.2f, 1.0f);
    aiColor4D ambient;
    if (AI_SUCCESS == aiGetMaterialColor(mtl, AI_MATKEY_COLOR_AMBIENT, &ambient))
        color4_to_float4(&ambient, c);
    memcpy(aMat.ambient, c, sizeof(c));

    set_float4(c, 0.0f, 0.0f, 0.0f, 1.0f);
    aiColor4D specular;
    if (AI_SUCCESS == aiGetMaterialColor(mtl, AI_MATKEY_COLOR_SPECULAR, &specular))
        color4_to_float4(&specular, c);
    memcpy(aMat.specular, c, sizeof(c));

    set_float4(c, 0.0f, 0.0f, 0.0f, 1.0f);
    aiColor4D emission;
    if (AI_SUCCESS == aiGetMaterialColor(mtl, AI_MATKEY_COLOR_EMISSIVE, &emission))
        color4_to_float4(&emission, c);
    memcpy(aMat.emissive, c, sizeof(c));

    float shininess = 0.0;
    unsigned int max;
    aiGetMaterialFloatArray(mtl, AI_MATKEY_SHININESS, &shininess, &max);
    aMat.shininess = shininess;

    glGenBuffers(1, &(aMesh.uniformBlockIndex));
    glBindBuffer(GL_UNIFORM_BUFFER, aMesh.uniformBlockIndex);
    glBufferData(GL_UNIFORM_BUFFER, sizeof(aMat), (void *)(&aMat), GL_STATIC_DRAW);

    myMeshes.push_back(aMesh);
  }
}

void Mesh::recursive_render(const aiScene *sc, const aiNode* nd){
  // draw all meshes assigned to this node
  for (unsigned int n = 0; n < nd->mNumMeshes; ++n){
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, myMeshes[nd->mMeshes[n]].texIndex);

    // bind VAO
    glBindVertexArray(myMeshes[nd->mMeshes[n]].vao);

    // draw
    glDrawElements(GL_TRIANGLES, myMeshes[nd->mMeshes[n]].numFaces * 3, GL_UNSIGNED_INT, 0);
  }

  // draw all children
  for (unsigned int n = 0; n < nd->mNumChildren; ++n){
      recursive_render(sc, nd->mChildren[n]);
  }
}