Re: [PyMOL] Question about custom CGO objects

[Gilleain T. <gil...@gm...>]

Hi,

As I understand it, you can either make cgo's that are 'static' in  
shape (like a 3D stamp) or use pymol.callback objects, which can use  
arbitrary opengl commands (such as matrix rotations).

I actually made a cone, in response to someone's query, only I had to  
use callbacks to get triangle fans, and it appears that macpymol  
doesn't have opengl compiled in by default or something.

Here is my Cone class (mostly nicked from a tutorial on the web):

import math
from pymol.opengl.gl import *
from pymol.callback import Callback
from pymol import cmd

class Cone(Callback):

     def get_extent(self):
         return [[-10.0, -10.0, -10.0], [10.0, 10.0, 10.0]]

     def __call__(self):
         glPushMatrix()
         glRotatef(xRot, 1.0, 0.0, 0.0)
         glRotatef(yRot, 0.0, 1.0, 0.0)

         # Begin a triangle fan
         glBegin(GL_TRIANGLE_FAN)

         # Pinnacle of cone is shared vertex for fan, moved up z-axis
         # to produce a cone instead of a circle
         glVertex3f(0.0, 0.0, 75.0)

         # Loop around in a circle and specify even points along the  
circle
         # as the vertices of the triangle fan
         angle = 0.0
         while angle < 2.0 * math.pi:

             # Calculate x and y position of the next vertex
             x = 50.0 * math.sin(angle)
             y = 50.0 * math.cos(angle)

             # Alternate color between red and green
             if((iPivot %2) == 0):
                 glColor3f(0.0, 1.0, 0.0)
             else:
                 glColor3f(1.0, 0.0, 0.0)

             # Increment pivot to change color next time
             iPivot += 1

             # Specify the next vertex for the triangle fan
             glVertex2f(x, y)
             angle += (math.pi / 8.0)

         # Done drawing fan for cone
         glEnd()

         # Begin a new triangle fan to cover the bottom
         glBegin(GL_TRIANGLE_FAN)

         # Center of fan is at the origin
         glVertex2f(0.0, 0.0)
         angle = 0.0
         while angle < 2.0 * math.pi:
             # Calculate x and y position of the next vertex
             x = 50.0 * math.sin(angle)
             y = 50.0 * math.cos(angle)

             # Alternate color between red and green
             if((iPivot %2) == 0):
                 glColor3f(0.0, 1.0, 0.0)
             else:
                 glColor3f(1.0, 0.0, 0.0)

             # Increment pivot to change color next time
             iPivot += 1

             # Specify the next vertex for the triangle fan
             glVertex2f(x, y)
             angle += (math.pi / 8.0)

         # Done drawing the fan that covers the bottom
         glEnd()

         # Restore transformations
         glPopMatrix()


rx, ry, rz = 1, 2, 3
cmd.load_callback(Cone(), 'cone')


Gilleain Torrance

On 8 Nov 2005, at 06:44, Andrew Wollacott wrote:

> Hey all,
> I recently made a cone class that will display cones using pymol
> cgo's.  I built the cones using triangles as suggested by Warren  Now
> I need to get the cones oriented properly, so I was wondering if it's
> possible to apply a GL or rotation matrix when making the cgo.  I
> guess if I can't do this then I can rotate the vertices of each
> individual triangle, but I only want to do this as a last resort.
>
> Any help would be appreciated.
>
> Thanks,
>
> Andrew Wollacott, PhD
> Baker Research Group
> The University of Washington
>
>
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