Question

我正在尝试从3ds Max正确导入.OBJ文件。我使用glBegin（）＆amp; glEnd（）来自上一个问题，但显然性能很差，所以我现在尝试使用glDrawElements。

我正在导入棋盘，游戏棋子等。棋盘，每个游戏棋子以及棋盘上的每个方块都存储在结构GroupObject中。我存储数据的方式如下：

struct Vertex
{
    float position[3];
    float texCoord[2];
    float normal[3];
    float tangent[4];
    float bitangent[3];
};

struct Material
{
    float ambient[4];
    float diffuse[4];
    float specular[4];
    float shininess;        // [0 = min shininess, 1 = max shininess]
    float alpha;            // [0 = fully transparent, 1 = fully opaque]

    std::string name;
    std::string colorMapFilename;
    std::string bumpMapFilename;

   std::vector<int> indices;
   int id;
  };

 //A chess piece or square
 struct GroupObject
 {
     std::vector<Material *> materials;
     std::string    objectName;
     std::string    groupName;
     int      index;
 };

所有顶点都是三角形，因此始终有3个点。当我循环遍历obj文件中的面f部分时，我存储了v0，v1和＆amp;材料 - >指数中的v2。（我正在做v [0-2] - 1来说明obj文件是基于1的，我的向量是基于0的。

所以当我进入render方法时，我试图遍历每个对象，它遍历附加到该对象的每个材质。我设置了材料信息并尝试使用glDrawElements。但是，屏幕是黑色的。当我使用与该材料相关的所有索引遍历每个不同的材料时，我能够很好地绘制模型，并且它使模型很好。这一次，所以我可以使用模板缓冲区来选择GroupObject，我改变了循环，但是屏幕是黑色的。

更新将原始渲染循环替换为当前渲染循环并截取其结果这是我的渲染循环。我唯一改变的是for循环，所以它们遍历每个对象，然后依次遍历对象中的每个材质。

void GLEngine::drawModel()
{
ModelTextures::const_iterator iter;
GLuint texture = 0;

glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

// Vertex arrays setup
glEnableClientState( GL_VERTEX_ARRAY );
glVertexPointer(3, GL_FLOAT, model.getVertexSize(), model.getVertexBuffer()->position);

glEnableClientState( GL_NORMAL_ARRAY );
glNormalPointer(GL_FLOAT, model.getVertexSize(), model.getVertexBuffer()->normal);

glClientActiveTexture( GL_TEXTURE0 );
glEnableClientState( GL_TEXTURE_COORD_ARRAY );
glTexCoordPointer(2, GL_FLOAT, model.getVertexSize(), model.getVertexBuffer()->texCoord);

glUseProgram(blinnPhongShader);

objects = model.getObjects();
// Loop through objects...
for( int i=0 ; i < objects.size(); ++i ) 
{
    ModelOBJ::GroupObject *object = objects[i];

    // Loop through materials used by object...
    for( int j=0 ; j<object->materials.size() ; ++j ) 
    {
        ModelOBJ::Material *pMaterial = object->materials[j];

        glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, pMaterial->ambient);
        glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, pMaterial->diffuse);
        glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, pMaterial->specular);
        glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, pMaterial->shininess * 128.0f);

        if (pMaterial->bumpMapFilename.empty())
        {

             //Bind the color map texture.
            texture = nullTexture;
            if (enableTextures)
            {
                iter = modelTextures.find(pMaterial->colorMapFilename);

                if (iter != modelTextures.end())
                    texture = iter->second;
            }

            glActiveTexture(GL_TEXTURE0);
            glEnable(GL_TEXTURE_2D);
            glBindTexture(GL_TEXTURE_2D, texture);

             //Update shader parameters.
            glUniform1i(glGetUniformLocation(
                blinnPhongShader, "colorMap"), 0);
            glUniform1f(glGetUniformLocation(
                blinnPhongShader, "materialAlpha"), pMaterial->alpha);
        }
        //glDrawElements( GL_TRIANGLES, pMaterial->triangleCount * 3, GL_UNSIGNED_INT, &pMaterial->indices.front() );
        glDrawElements( GL_TRIANGLES, pMaterial->triangleCount * 3, GL_UNSIGNED_INT, model.getIndexBuffer() + pMaterial->startIndex );

    }

}
glDisableClientState(GL_NORMAL_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glBindTexture(GL_TEXTURE_2D, 0);
    glUseProgram(0);
    glDisable(GL_BLEND);
}

以上是上述方法的内容： http://img844.imageshack.us/img844/3793/chess4.png

我不知道我错过了什么，这很重要。如果它也有帮助，这里是我读取'f'面线并将信息存储在pMaterial-＆gt;指数中的obj导入器中的位置。

 else if (sscanf(buffer, "%d/%d/%d", &v[0], &vt[0], &vn[0]) == 3) // v/vt/vn
        {
            fscanf(pFile, "%d/%d/%d", &v[1], &vt[1], &vn[1]);
            fscanf(pFile, "%d/%d/%d", &v[2], &vt[2], &vn[2]);

            v[0] = (v[0] < 0) ? v[0] + numVertices - 1 : v[0] - 1;
            v[1] = (v[1] < 0) ? v[1] + numVertices - 1 : v[1] - 1;
            v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1;

currentMaterial->indices.push_back(v[0]);
currentMaterial->indices.push_back(v[1]);
currentMaterial->indices.push_back(v[2]);

更新2

当前输出：http://img337.imageshack.us/img337/860/chess4s.png

Answer 1

我能够使用以下代码修复模型

glDrawElements( GL_TRIANGLES, pMaterial->triangleCount * 3, GL_UNSIGNED_INT, model.getIndexBuffer() + pMaterial->startIndex );

当我完成导入模型后，我经历了一个triangleCount＆amp;像这样设置startIndex。这是我的解决方案：

for (int i = 0; i < static_cast<int>(m_attributeBuffer.size()); i++)
{
    if (m_attributeBuffer[i] != materialId)
    {
        materialId = m_attributeBuffer[i];
        ++numMaterials;
    }
}

// Allocate memory for the materials and reset counters.
m_numberOfObjectMaterials = numMaterials;
m_materials.resize(m_numberOfObjectMaterials);
numMaterials = 0;
materialId = -1;

// Build the meshes. One mesh for each unique material.
for (int i = 0; i < static_cast<int>(m_attributeBuffer.size()); i++)
{
    if (m_attributeBuffer[i] != materialId)
    {
        materialId = m_attributeBuffer[i];
        m = m_ObjectMaterials[materialId];
        m->startIndex = i * 3;
        m->triangleCount = 0;
        ++m->triangleCount;
    }
    else
    {
        ++m->triangleCount;
    }
}

使用glDrawElements不会绘制我的.obj文件

1 个答案: