带索引的pyOpenGL VBOs

Question

我想在pyOpenGL中用带索引的VBO绘制一个矩形。我正在使用glDrawRangeElements()这个函数，但每次在调用glDrawRangeElements的那一行时，总是出现同样的错误：

WindowsError: exception: access violation reading 0x00000000

我尝试了很多方法，也在网上找解决方案，整天研究代码示例，但现在真的不知道该怎么继续了。如果这里有人能帮我就太好了。

下面是出错的代码部分：

vertexPositions = [[-0.75, -0.75,  0.0],
                    [0.75, -0.75,  0.0],
                    [0.75,  0.75,  0.0],
                   [-0.75,  0.75,  0.0] ]
vertexIndices = [0, 1, 2,
                 1, 2, 3]
vertexComponents = 3

positionBufferObject = None
indexBufferObject = None

x = 0

def glGenVertexArray():
    vao_id = GL.GLuint(0)
    vertex_array_object.glGenVertexArrays(1, vao_id)
    return vao_id.value

def initialize_vertex_buffer():
    global positionBufferObject, indexBufferObject

    indexBufferObject = GL.glGenBuffers(1)
    GL.glBindBuffer(GL.GL_ELEMENT_ARRAY_BUFFER, indexBufferObject)

    array_type = (GL.GLushort * len(vertexIndices))
    GL.glBufferData(GL.GL_ELEMENT_ARRAY_BUFFER, len(vertexIndices) * 2, 
                         array_type(*vertexIndices), GL.GL_STATIC_DRAW)
    GL.glBindBuffer(GL.GL_ELEMENT_ARRAY_BUFFER, 0)

    positionBufferObject = GL.glGenBuffers(1)
    GL.glBindBuffer(GL.GL_ARRAY_BUFFER, positionBufferObject)

    array_type = (GL.GLfloat * len(vertexPositions))
    GL.glBufferData(GL.GL_ARRAY_BUFFER,
                    len(vertexPositions[0])*len(vertexPositions)*sizeOfFloat,
                    array_type(*vertexPositions), GL.GL_STATIC_DRAW
    )
    GL.glBindBuffer(GL.GL_ARRAY_BUFFER, 0)
    glBindVertexArray( glGenVertexArray() )


def init():
    initialize_vertex_buffer()


def display():
    global x
    GL.glClearColor(0.0, 0.0, 0.0, 0.0)
    GL.glClear(GL.GL_COLOR_BUFFER_BIT)

    GL.glMatrixMode(GL.GL_MODELVIEW)
    GL.glEnableClientState(GL.GL_VERTEX_ARRAY)
    GL.glEnableClientState(GL.GL_INDEX_ARRAY)
    GL.glLoadIdentity()
    GL.glTranslate(0, 0, -5)
    GL.glRotate(x, 0, 1, 0)

    GL.glBindVertexArray(glGenVertexArray())
    GL.glBindBuffer(GL.GL_ARRAY_BUFFER, positionBufferObject)
    GL.glBindBuffer(GL.GL_ELEMENT_ARRAY_BUFFER, indexBufferObject)
    GL.glEnableVertexAttribArray(0)

    GL.glDrawRangeElements(GL.GL_TRIANGLES,0, 4, 6, GL.GL_UNSIGNED_SHORT, c_void_p(0))

    #GL.glVertexAttribPointer(0, vertexComponents, GL.GL_FLOAT, False, 0, null)

    #GL.glDrawArrays(GL.GL_QUADS, 0, len(vertexPositions) / vertexComponents)

    GL.glDisableVertexAttribArray(0)
    GL.glDisableClientState(GL.GL_VERTEX_ARRAY)
    GL.glDisableClientState(GL.GL_INDEX_ARRAY)

    pygame.display.flip()

我得承认我对这些东西还不是很了解，只是在努力理解，因为我需要它来做一个项目。如果还有其他我忽略的错误，请告诉我；)

提前谢谢你们

错误处理图形编程 opengl 3d渲染 vbo 矩形绘制访问冲突 glDrawRangeElements

带索引的pyOpenGL VBOs

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