使用带有 PyQt5 和 OpenGL 的 VBO 绘制多个对象？

Question

我正在尝试使用 pyqt5 在 pyopengl 中渲染多个对象。在遵循教程之后，我创建了一个 3D 网格，它上传了一个波前 obj 文件并用纹理渲染它。这对我有用：

class Model:
    def __init__(self, file_name, texture_name):
        self.object = ObjectLoader()
        self.object.load_model(file_name)

        //creating and compiling shaders

        glUseProgram(shader)

        vertex_buffer_object = GLuint(0)
        glGenBuffers(1, vertex_buffer_object)
        glBindBuffer(GL_ARRAY_BUFFER,  vertex_buffer_object)
        glBufferData(GL_ARRAY_BUFFER, len(self.object.model) * 4, self.object.c_model, GL_DYNAMIC_DRAW) 
        glDrawArrays(GL_TRIANGLES, 0, len(self.object.vertex_index))
        # vertices
        vertex_offset = 0
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 3, ctypes.c_void_p(vertex_offset))
        glEnableVertexAttribArray(0)

        # textures
        texture_offset = len(self.object.vertex_index) * 12
        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 2, ctypes.c_void_p(texture_offset))
        glEnableVertexAttribArray(1)

        # normals
        normal_offset = texture_offset + len(self.object.texture_index) * 8
        glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 3, ctypes.c_void_p(normal_offset))
        glEnableVertexAttribArray(2)

        texture = GLuint(0)
        glGenTextures(1, texture)
        glBindTexture(GL_TEXTURE_2D, texture)
        # texture wrapping
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
        # texture filtering
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)

        glEnable(GL_BLEND)
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)

        image = Image.open(texture_name)
        flipped_image = image.transpose(Image.FLIP_TOP_BOTTOM)
        image_data = image.convert("RGB").tobytes()
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image.width, image.height, 0, GL_RGB, GL_UNSIGNED_BYTE, image_data)
      // setting the view, projection etc matrix     

由于我使用的是 PyQt5，所以如果我加载对象，我就有这个类：

class Obj(QOpenGLWidget):
    def __init__(self, parent):
        QOpenGLWidget.__init__(self, parent)
           
    def initializeGL(self):
        glClearColor(82/255, 95/255, 107/255, 1.0)
        glEnable(GL_DEPTH_TEST)         
        
        self.model = Model("....obj", "texture.png")     
            
        
    def paintGL(self):
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
        glDrawArrays(GL_TRIANGLES, 0, len(self.model.object.vertex_index))
        
   
        self.update()
        
        
    def resizeGL(self, width, height):
        glViewport(0, 0, width, height)

我正在努力在Obj 类中创建另一个Model。我尝试在initializeGL 中创建它并在paintGL 中使用另一个glDrawArrays 调用进行渲染，但没有发生任何事情，或者没有任何预期......知道我做错了什么吗？

Answer 1

您必须使用Vertex Array Object。顶点数组对象存储提供顶点数据所需的所有状态。

模型的构造函数只创建所有需要的 OpenGL 对象。着色器程序不是模型的一部分。对所有型号使用相同的程序：

class Model:
    def __init__(self, file_name, texture_name):
        self.object = ObjectLoader()
        self.object.load_model(file_name)

        # create vertex array object
        self.vao = glGenVertexArrays(1)
        glBindVertexArray(self.vao)

        vertex_buffer_object = GLuint(0)
        glGenBuffers(1, vertex_buffer_object)
        glBindBuffer(GL_ARRAY_BUFFER,  vertex_buffer_object)
        glBufferData(GL_ARRAY_BUFFER, len(self.object.model) * 4, self.object.c_model, GL_DYNAMIC_DRAW) 
        glDrawArrays(GL_TRIANGLES, 0, len(self.object.vertex_index))

        # vertices
        vertex_offset = 0
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 3, ctypes.c_void_p(vertex_offset))
        glEnableVertexAttribArray(0)

        # textures
        texture_offset = len(self.object.vertex_index) * 12
        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 2, ctypes.c_void_p(texture_offset))
        glEnableVertexAttribArray(1)

        # normals
        normal_offset = texture_offset + len(self.object.texture_index) * 8
        glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 3, ctypes.c_void_p(normal_offset))
        glEnableVertexAttribArray(2)

        # create texture
        self.texture = GLuint(0)
        glGenTextures(1, self.texture)
        glBindTexture(GL_TEXTURE_2D, self.texture)
        # texture wrapping
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
        # texture filtering
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)

        image = Image.open(texture_name)
        flipped_image = image.transpose(Image.FLIP_TOP_BOTTOM)
        image_data = image.convert("RGB").tobytes()
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image.width, image.height, 0, GL_RGB, GL_UNSIGNED_BYTE, image_data)

向绑定OpenGL对象（VAO和纹理）并绘制网格的类添加一个方法：

class Model:
    # [...]

    def draw(self):

        // bind texture
        glBindTexture(GL_TEXTURE_2D, self.texture)

        // create vertex array object
        glBindVertexArray(self.vao)

        // draw object
        glDrawArrays(GL_TRIANGLES, 0, len(self.object.vertex_index))

通过此设置，您可以绘制多个模型：

class Obj(QOpenGLWidget):
    def __init__(self, parent):
        QOpenGLWidget.__init__(self, parent)

    def initializeGL(self):
        glClearColor(82/255, 95/255, 107/255, 1.0)
        glEnable(GL_DEPTH_TEST)
        glEnable(GL_BLEND)
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)

        self.model1 = Model("....obj", "texture.png") 
        self.model2 = Model("....obj", "texture2.png")  
        # [...] 

    def paintGL(self):
        
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
        
        # install program
        glUseProgram(self.shader)

        # setting the view, projection etc matrix
        # [...]
        
        self.model1.draw()
        self.model2.draw()
        # [...] 
        
        self.update()
        
    def resizeGL(self, width, height):
        glViewport(0, 0, width, height)

模型也可以组织成一个列表：

class Obj(QOpenGLWidget):
   # [...]

    def initializeGL(self):
        # [...]

        self.models = [
            Model("....obj", "texture.png"),
            Model("....obj", "texture2.png")  
            # [...]
        ] 

    def paintGL(self):
        # [...]

        for model in self.models:
            model.draw()

        # [...]