Vfrdtyky

I am trying to create a simple scene with pyopengl, but I keep getting runtime error. I am using glfw for displaying opengl scene.

I am using python because I would like to include opengl in some other python projects.

I am on a macOS Mojave (10.14), Python 3.7

Error:

Traceback (most recent call last):

File "main.py", line 109, in <module>

main()

File "main.py", line 64, in main

shader = OpenGL.GL.shaders.compileProgram(s.vertex(), s.fragment())

File "slib/python3.7/site-packages/OpenGL/GL/shaders.py", line 196, in         

compileProgram

program.check_validate()

File "lib/python3.7/site-packages/OpenGL/GL/shaders.py", line 108, in 

check_validate

glGetProgramInfoLog( self ),

RuntimeError: Validation failure (0): b'Validation Failed: No vertex 

array object bound.n'

Code:

import glfw

from OpenGL.GL import *

import OpenGL.GL.shaders

import numpy as np





def trikotnik():

    trikotnik = np.array([

        -0.5, -0.5, 0.0,

        0.5, -0.5, 0.0,

        0.0, 0.5, 0.0

    ], dtype=np.float32)

    return trikotnik





class Shaders:

    def __init__(self):

        pass



    def vertex(self):

        v = """

        #version 330

        in vec4 position; 

        void main() { 

            gl_Position = position; 

        } 

        """

        return OpenGL.GL.shaders.compileShader(v, GL_VERTEX_SHADER)



    def fragment(self):

        f = """

        #version 330

        out vec4 fragColor;

        void main() { 

            fragColor = vec4( 0, 1, 0, 1 );

        } 

        """

        return OpenGL.GL.shaders.compileShader(f, GL_FRAGMENT_SHADER)





def main():

    # Initialize the library

    if not glfw.init():

        return

    glfw.window_hint(glfw.CONTEXT_VERSION_MAJOR, 3)

    glfw.window_hint(glfw.CONTEXT_VERSION_MINOR, 2)

    glfw.window_hint(glfw.OPENGL_PROFILE, glfw.OPENGL_CORE_PROFILE)

    glfw.window_hint(glfw.OPENGL_FORWARD_COMPAT, GL_TRUE)



    # Create a windowed mode window and its OpenGL context

    window = glfw.create_window(640, 480, "Hello World", None, None)

    if not window:

        glfw.terminate()

        return



    # Make the window's context current

    glfw.make_context_current(window)



    # Creating shaders

    s = Shaders()

    shader = OpenGL.GL.shaders.compileProgram(s.vertex(), s.fragment())



    # Creating vertex buffer object on gpu

    VBO = glGenBuffers(1)

    glBindBuffer(GL_ARRAY_BUFFER, VBO)

    # Load data on array buffer...32 = size in bytes 9x4

    # GL_STATIC_DRAW: The vertex data will be uploaded once and drawn many times.

    glBufferData(GL_ARRAY_BUFFER, 32, trikotnik(), GL_STATIC_DRAW)

    glBindBuffer(GL_ARRAY_BUFFER, VBO)



    position = glGetAttribLocation(shader, "position")

    glVertexAttribPointer(

        position,  # attribute 0. No particular reason for 0, but must match the layout in the shader.

        3,  # size

        GL_FLOAT,  # type

        GL_FALSE,  # normalized

        0,  # stride

        None  # array buffer offset

    )

    glEnableVertexAttribArray(position)



    glUseProgram(shader)



    glClearColor(0, 107, 179, 1.0)



    # Loop until the user closes the window

    while not glfw.window_should_close(window):

        # Render here, e.g. using pyOpenGL



        # Clear color buffer

        glClear(GL_COLOR_BUFFER_BIT)



        # Draw

        glDrawArrays(GL_TRIANGLES, 0, 3)



        # Swap front and back buffers

        glfw.swap_buffers(window)

        # Poll for and process events

        glfw.poll_events()



    glfw.terminate()





if __name__ == "__main__":

    main()

I found this in source code:

validate (keyword only) -- if False, suppress automatic
validation against current GL state. In advanced usage
the validation can produce spurious errors. Note: this
function is not really intended for advanced usage,
if you're finding yourself specifying this flag you
likely should be using your own shader management code.

I try to set it to False but I am still getting an error.

Either you use a Vertex Array Object or you switch to a compatibility profile context glfw.window_hint(glfw.OPENGL_PROFILE, glfw.OPENGL_COMPAT_PROFILE). In core profile you must have a named VAO, it is not optional.

Create and bind a VAO before specifying the array of vertex array data:

VAO = glGenVertexArrays(1)

glBindVertexArray(VAO)



glVertexAttribPointer(

    position,  # attribute 0. No particular reason for 0, but must match the layout in the shader.

    3,  # size

    GL_FLOAT,  # type

    GL_FALSE,  # normalized

    0,  # stride

    None  # array buffer offset

)

glEnableVertexAttribArray(position)