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pythonopenglglutpyopengl

PyOpenGL depth test doesn't do anything

I initialize depth testing here:

def _initGL(self):
    glEnable(GL_DEPTH_TEST)
    glDepthMask(GL_TRUE)
    glDepthFunc(GL_NEVER)

    glDepthRange(0.0, 1.0)
    glClearDepth(1.0)

Then, later I display some geometry

def _display(self):
    print(glGetBooleanv(GL_DEPTH_TEST))
    print(glGetIntegerv(GL_DEPTH_FUNC)==GL_NEVER)
    print(glGetFloatv(GL_DEPTH_RANGE))
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
    glUseProgram(self._program)
    #This is a wrapped VBO doing the drawing. That actually works.
    self._buffer.draw()
    glutSwapBuffers()

The output from the prints is

1 True [0. 1.]

So there should be no doubt that depth testing is on and set to never let any fragment pass, and yet:

These squares should not show up.

EDIT: I just ran it on a windows machine instead (this was done on Ubuntu) and everything works perfectly.

Solution

  • Probably the default framebuffer (Ubuntu) has no depth buffer. You've to specify the display mode by glutInitDisplayMode, before the OpenGL window is created by glutCreateWindow.
    GLUT_DEPTH selects a window with a depth buffer. e.g.:

    glutInitDisplayMode(GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE)