Python OpenGL glRotatef does not rotate the correct amount

Question

I use Pycharm and coupled OpenGL with pygame. I have a problem with the OpenGL method glRotatef. It seems like it does not rotate the right amount. I have a class which has the 3-dimensional coordinates xPos,yPos,zPos. The class is drawn with this method:

def draw(self):
    OpenGL.GL.glPushMatrix()
    OpenGL.GL.glTranslate(self.xPos, self.yPos, self.zPos)
    OpenGL.GL.glRotatef(self.remindturn, 0, 1, 0)
    OpenGL.GL.glColor3f(1,0,0)
    OpenGL.GL.glBegin(OpenGL.GL.GL_TRIANGLES)
    OpenGL.GL.glVertex3f(self.xPos-100, self.yPos+50, self.zPos)
    OpenGL.GL.glVertex3f(self.xPos + 100, self.yPos + 50, self.zPos)
    OpenGL.GL.glVertex3f(self.xPos, self.yPos -50, self.zPos)
    OpenGL.GL.glEnd()
    OpenGL.GL.glPopMatrix()

remindturn is defined by this method:

def remindtheturn(self):
    if self.keypressed == True :
        self.remindturn = self.mouseturnX

keypressed is defined by this method:

def feel(self , event):
    if event.type == pygame.KEYDOWN :
        if event.key == pygame.K_w :
            self.keypressed = True
    if event.type == pygame.KEYUP :
        if event.key == pygame.K_w :
            self.keypressed = False

mouseturnX and mouseturnY are defined that way:

def mouseturn(self):
    mouse_pos = pygame.mouse.get_pos()
    if mouse_pos[0] > 250 :
        self.mouseturnX = (mouse_pos[0] - 250) * 0.1
    if mouse_pos[0] < 250 :
        self.mouseturnX = (-250 + mouse_pos[0])*0.1
    if mouse_pos[1] > 250 :
        self.mouseturnY = -(mouse_pos[1] -250) *0.5
    if mouse_pos[1] < 250 :
        self.mouseturnY = -(-250 + mouse_pos[1])*0.5

This all leads to the camera method. The camera has the coordinates xCam, yCam, and zCam.

def camera(self):
    self.xCam = math.sin(self.mouseturnX) * self.camdist + self.xPos
    self.yCam = self.yPos + self.mouseturnY
    self.zCam = math.cos(self.mouseturnX) * self.camdist + self.zPos
    OpenGL.GL.glViewport(0,0, 500, 500)
    OpenGL.GL.glMatrixMode(OpenGL.GL.GL_PROJECTION)
    OpenGL.GL.glLoadIdentity()
    OpenGL.GLU.gluPerspective(60, (500/500), 0.1, 10000.0)
    OpenGL.GL.glMatrixMode(OpenGL.GL.GL_MODELVIEW)
    OpenGL.GL.glLoadIdentity()
    OpenGL.GLU.gluLookAt(self.xCam, self.yCam, self.zCam, self.xPos, self.yPos, self.zPos, 0, 1, 0)

Following maths, the drawn object should always face the camera, when the key w is pressed. But it does not do so. It rotates, but not in the right amount.

I tried multiplying remindturn with 45, 90, 180, 270 and 360 and other famous angle numbers, nothing worked. I even translated the object back to the origin after rotating it, it did not help. I tried tan and atan as functions on the numbers I mentioned before, I even tried Pi. I do not know what is wrong with this code. I used the math behind this in Processing long ago, there it worked completely fine.

@Rabbid76 Yes, I want to rotate around the y-axis, because I want to use this mechanic in a 3rd person game. When the key is pressed, the object then is supposed to move and remindturn makes it turn into the direction it is going. When the key is released, remindturn saves the last value of mouseturnX, so the object stays rotated into the former direction of movement. — programming_noob, Dec 31 '22 at 17:07

score -1 · Accepted Answer · answered Jan 10 '23 at 13:56

-1

It needs a multiplicator for remindturn = mouseturnX*multiplicator. The multiplicator is 56.5. It is not perfect, but it works.

answered Jan 10 '23 at 13:56

programming_noob

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Python OpenGL glRotatef does not rotate the correct amount

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