OpenGL：球体减慢帧率

Question

我有一个 class 可以根据传入的堆栈计数、扇区计数和半径制作一个球体。问题是，每当我绘制球体时，我的帧速率都会从 57-60 fps 下降到 20 fps。

这是我绘制球体的方式：

    def draw_edges(self):
        """Draws the sphere's edges"""
        glPushMatrix()
        glTranslate(self.position[0], self.position[1], self.position[2])
        glRotate(self.rotation[3],self.rotation[0],self.rotation[1],self.rotation[2])
        glPolygonMode(GL_FRONT_AND_BACK, GL_LINE)
        glBegin(GL_TRIANGLES)
        for edge in self.edges:
            for vertex in edge:
                glVertex3fv(self.vertices[vertex])
        glEnd()
        glPolygonMode(GL_FRONT_AND_BACK, GL_FILL)
        glPopMatrix()

有谁知道我怎样才能加快速度？

Answer 1

尝试摆脱嵌套循环。参见 Vertex Specification for a modern way of drawing meshes by the use of a Vertex Buffer Object and Vertex Array Object。

另一种（已弃用）可能性是使用固定功能属性。

OpenGL 4.6 API Compatibility Profile Specification; 10.3.3 Specifying Arrays for Fixed-Function Attributes; page 402

The commands
void VertexPointer( int size, enum type, sizei stride, const void *pointer );
void NormalPointer( enum type, sizei stride, const void *pointer );
void ColorPointer( int size, enum type, sizei stride, const void *pointer );
[...]
specify the location and organization of arrays to store vertex coordinates, normals, colors, [...] An individual array is enabled or disabled by calling one of
void EnableClientState( enum array );
void DisableClientState( enum array );
with array set to VERTEX_ARRAY, NORMAL_ARRAY, COLOR_ARRAY, [...], for the vertex, normal, color, [...] array, respectively.

在 class:

的构造函数中创建一个包含顶点属性数据的列表

def __init__(self):
    # [...]
   
    self.vertexArray = []
    for edge in self.edges:
        for vertex in edge:
            self.vertexArray.append(self.vertices[vertex])

使用数组指定顶点并绘制网格：

def draw_edges(self):
    """Draws the sphere's edges"""
    glPushMatrix()
    glTranslate(self.position[0], self.position[1], self.position[2])
    glRotate(self.rotation[3],self.rotation[0],self.rotation[1],self.rotation[2])
    glPolygonMode(GL_FRONT_AND_BACK, GL_LINE)
    
    glEnableClientState(GL_VERTEX_ARRAY)
    glVertexPointer(3, GL_FLOAT, 0, self.vertexArray)
    glDrawArrays(GL_TRIANGLES, 0, len(self.vertexArray))
    glDisableClientState(GL_VERTEX_ARRAY)
    
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL)
    glPopMatrix()

这是使用 VBO 和 VAO 实现现代解决方案的第一步（小）。

使用 Vertex Buffer Object:

可以获得进一步的性能提升

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

    self.vertexArray = []
    for edge in self.edges:
        for vertex in edge:
            self.vertexArray += self.verticies[vertex] # <--- flat list

    array = (GLfloat * len(self.vertexArray))(*self.vertexArray)
    self.vbo = glGenBuffers(1)        
    glBindBuffer(GL_ARRAY_BUFFER, self.vbo)
    glBufferData(GL_ARRAY_BUFFER, array, GL_STATIC_DRAW)
    glBindBuffer(GL_ARRAY_BUFFER, 0)

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

    glBindBuffer(GL_ARRAY_BUFFER, self.vbo)
    glVertexPointer(3, GL_FLOAT, 0, None)
    glBindBuffer(GL_ARRAY_BUFFER, 0)
    
    glEnableClientState(GL_VERTEX_ARRAY)
    glDrawArrays(GL_TRIANGLES, 0, len(self.vertexArray) // 3)
    glDisableClientState(GL_VERTEX_ARRAY)

    # [...]

OpenGL：球体减慢帧率

OpenGL: Sphere slowing down framerate

python

opengl

performance

pyopengl

opengl-compat