opengl读取obj模型文件 纹理贴图解析错误，求教！

[licmue]

]这几天一直在实现opengl加载obj模型，现在进度是：
单纯加载模型无贴图是可以，如下图01

但是加上贴图就变成这样，如下图02（眼是俩黑窟窿有木有，晕啊）

图03


图02 是当我将glTexEnvf()函数第三个参数设为GL_MODULATE时的，图03是设为GL_BLEND时的。
以下是部分代码

//
//绘制函数
//
GLvoid GLObj_Model::glDraw_triangle(GLvoid)
{
	std::cout << "checkpoint into glDraw_triangle()... ..." << std::endl;
	GLObj_Block *block_pointer = NULL;			//指向索引块
	GLObj_Triangles *triangle_pointer = NULL;	//指向三角形面片数组
	block_pointer = obj_root.block_ptr;//指向第一块索引块
	while(block_pointer != NULL)
	{
		//std::cout << "into while() loop ... ..." << std::endl;
		//设置材质和纹理贴图
		glSet_material_info(block_pointer->material_name);
		glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glEnable(GL_TEXTURE_2D);
		triangle_pointer = block_pointer->triangles_ptr;//指向本索引块第一个三角形面片
		glBegin(GL_TRIANGLES);
		for(int i = 0; i < block_pointer->this_block_triangle_num; i++)
		{
			//第一个顶点
			glNormal3fv((triangle_pointer[i]).normal[0]);
			glTexCoord2fv((triangle_pointer[i]).texcoord[0]);
			glVertex3fv((triangle_pointer[i]).vertex[0]);

			//第二个顶点
			glNormal3fv((triangle_pointer[i]).normal[1]);
			glTexCoord2fv((triangle_pointer[i]).texcoord[1]);
			glVertex3fv((triangle_pointer[i]).vertex[1]);

			//第三个顶点
			glNormal3fv((triangle_pointer[i]).normal[2]);
			glTexCoord2fv((triangle_pointer[i]).texcoord[2]);
			glVertex3fv((triangle_pointer[i]).vertex[2]);
		}
		glEnd();
		glDisable(GL_TEXTURE_2D);
		block_pointer = block_pointer->next;
	}
	std::cout << "checkpoint leaving glDraw_triangle()... ..." << std::endl;
}

//
//glSet_material_info()函数实现设置当前块（我是按使用相同材质和纹理的三角形面片分块的）的
//材质信息和绑定纹理贴图
//
//mat_name参数为本块所需的材质的材质名，通过材质名在材质信息链表中查找对应的材质和纹理
//
GLvoid GLObj_Model::glSet_material_info(char *mat_name)
{
	GLObj_Material *ptr = NULL;//
	ptr = obj_root.material_ptr;//指针指向材质信息链表，存储材质信息以及纹理贴图对应的textureID
	while(ptr != NULL)
	{
		if(strcmp(ptr->material_name, mat_name) == 0)//通过mat_name查找
		{
			break;
		}
		ptr = ptr->next;
	}

	if(ptr != NULL) //找到对应的材质信息
	{
		//std::cout << "checkpoint into glSet_material_info()... ..." << std::endl;
		glMaterialfv(GL_FRONT, GL_AMBIENT, ptr->Ka);
		glMaterialfv(GL_FRONT, GL_DIFFUSE, ptr->Kd);
		glMaterialfv(GL_FRONT, GL_SPECULAR, ptr->Ks);
		glMaterialfv(GL_FRONT, GL_SHININESS, &(ptr->Sh));
		glMaterialfv(GL_FRONT, GL_EMISSION, ptr->Em);
		
		if(ptr->textureID)
		{
			glBindTexture(GL_TEXTURE_2D, ptr->textureID);//绑定纹理
		}
	}
}