ex_cube.py

# coding=utf-8
"""Drawing a simple cube with OpenGL"""

import glfw
from OpenGL.GL import *
import OpenGL.GL.shaders
import numpy as np
import sys, os.path
sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
import grafica.basic_shapes as bs
import grafica.easy_shaders as es
import grafica.transformations as tr

__author__ = "Daniel Calderon"
__license__ = "MIT"


# A class to store the application control
class Controller:
    fillPolygon = True


# we will use the global controller as communication with the callback function
controller = Controller()


def on_key(window, key, scancode, action, mods):

    if action != glfw.PRESS:
        return
    
    global controller

    if key == glfw.KEY_SPACE:
        controller.fillPolygon = not controller.fillPolygon

    elif key == glfw.KEY_ESCAPE:
        glfw.set_window_should_close(window, True)

    else:
        print('Unknown key')


if __name__ == "__main__":

    # Initialize glfw
    if not glfw.init():
        glfw.set_window_should_close(window, True)

    width = 600
    height = 600

    window = glfw.create_window(width, height, "Simple Cube - Modern OpenGL", None, None)

    if not window:
        glfw.terminate()
        glfw.set_window_should_close(window, True)

    glfw.make_context_current(window)

    # Connecting the callback function 'on_key' to handle keyboard events
    glfw.set_key_callback(window, on_key)

    # Creating our shader program and telling OpenGL to use it
    pipeline = es.SimpleTransformShaderProgram()
    glUseProgram(pipeline.shaderProgram)

    # Setting up the clear screen color
    glClearColor(0.15, 0.15, 0.15, 1.0)

    # As we work in 3D, we need to check which part is in front,
    # and which one is at the back
    glEnable(GL_DEPTH_TEST)

    # Creating shapes on GPU memory
    shapeCube = bs.createRainbowCube()
    gpuCube = es.GPUShape().initBuffers()
    pipeline.setupVAO(gpuCube)
    gpuCube.fillBuffers(shapeCube.vertices, shapeCube.indices, GL_STATIC_DRAW)


    while not glfw.window_should_close(window):
        # Using GLFW to check for input events
        glfw.poll_events()

        # Filling or not the shapes depending on the controller state
        if (controller.fillPolygon):
            glPolygonMode(GL_FRONT_AND_BACK, GL_FILL)
        else:
            glPolygonMode(GL_FRONT_AND_BACK, GL_LINE)

        # Clearing the screen in both, color and depth
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)

        theta = glfw.get_time()
        Rx = tr.rotationX(np.pi/3)
        Ry = tr.rotationY(theta)
        transform = np.matmul(Rx, Ry)

        # Drawing the Cube
        glUniformMatrix4fv(glGetUniformLocation(pipeline.shaderProgram, "transform"), 1, GL_TRUE, transform)
        pipeline.drawCall(gpuCube)

        # Once the drawing is rendered, buffers are swap so an uncomplete drawing is never seen.
        glfw.swap_buffers(window)

    # freeing GPU memory
    gpuCube.clear()

    glfw.terminate()