CODEWITHSUNDEEP
pythonopengl3dpyopengl
Kks
Kks

Reputation: 41

PyOpengl loaded vertex data does not display via VBO

I'm trying to display a STL file using pyopengl VBO but When i try it small amount of vertex list, it works fine. but When trying it with very long data which is loaded from STL file with exact same code, it displays nothing.

for example, with simple vertex data as list

test = [0.5, -0.5, 0.0, 1.0, 0.0, 0.0, -0.5, -0.5, 0.0, 0.0, 1.0, 0.0, 0.0,0.5, 0.0, 0.0, 0.0, 1.0 ]

but with big amount of data is not showing anything.

test = [0.5, -0.5, 1111.0, 1.0, 0.0, 0.0, -0.5, -11111.5, 0.0, 0.0, 1.0, 0.0, 0.0,0.5, 0.0, 0.0, 0.0, 1.0 ]

does someone know about this issue?

import glfw

from OpenGL.GL import *

import OpenGL.GL.shaders as shaders

import numpy

def main():
    if not glfw.init():
        return

    window = glfw.create_window(800, 600, "vbo test", None, None)

    if not window:
        glfw.terminate()
        return
    glfw.make_context_current(window)


    test = [0.5, -0.5, 0.0,        1.0, 0.0, 0.0,
            -0.5, -0.5, 0.0,      0.0, 1.0, 0.0,
            0.0,0.5, 0.0,       0.0, 0.0, 1.0 ]


    triangle = numpy.array(list(map(float,test)), dtype=numpy.float32)

    vertex_shader_source = """
                            #version 330 core
                            in vec3 vPosition;
                            in vec3 vColor;

                            out vec3 color;

                            uniform mat4 ModelViewProjectionMatrix;

                            void main()
                            {
                                color = vColor;

                                gl_Position = vec4(vPosition,1.0f) ;
                            }
                            """
    fragment_shader_cource = """
                            #version 330 core
                            in vec3 color;
                            
                            out vec4 outColor;
                            void main()
                            {
                                outColor = vec4(color,1.0f);
                            }
                             """



    vertex_shader = shaders.compileShader(vertex_shader_source, GL_VERTEX_SHADER)
    fragment_shader = shaders.compileShader(fragment_shader_cource, GL_FRAGMENT_SHADER)
    shader = shaders.compileProgram(vertex_shader, fragment_shader)

    VBO = glGenBuffers(1)
    glBindBuffer(GL_ARRAY_BUFFER, VBO)
    glBufferData(GL_ARRAY_BUFFER, triangle.itemsize * triangle.size, triangle, GL_STATIC_DRAW)

    position = glGetAttribLocation(shader, "vPosition")
    glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, 4*6, ctypes.c_void_p(0))
    glEnableVertexAttribArray(position)

    color = glGetAttribLocation(shader,"vColor")
    glVertexAttribPointer(color,3,GL_FLOAT,GL_FALSE, 4*6, ctypes.c_void_p(4*3))
    glEnableVertexAttribArray(color)
    glUseProgram(0)
    glUseProgram(shader)
    glClearColor(0, 0, 0, 0)

    while not glfw.window_should_close(window):
        glfw.poll_events()

        glClear(GL_COLOR_BUFFER_BIT)

        glDrawArrays(GL_TRIANGLES, 0,3)


        glfw.swap_buffers(window)

    glfw.terminate()


if __name__ == "__main__":
    main()

Upvotes: 1

Views: 135

Answers (1)

Rabbid76
Rabbid76

Reputation: 210968

See OpenGL Development on OS X and create an Core profile OpenGL 3.3 Context:

glfw.window_hint(glfw.CONTEXT_VERSION_MAJOR, 3)
glfw.window_hint(glfw.CONTEXT_VERSION_MINOR, 3)
glfw.window_hint(glfw.OPENGL_FORWARD_COMPAT, GL_TRUE)
glfw.window_hint(glfw.OPENGL_PROFILE, glfw.OPENGL_CORE_PROFILE)
window = glfw.create_window(800, 600, "vbo test", None, None)

Using a core profile context, you need to create a Vertex Array Object:

VAO = glGenVertexArrays(1)
glBindVertexArray(VAO)

Complete example:

import glfw
from OpenGL.GL import *
import OpenGL.GL.shaders as shaders
import numpy

def main():
    if not glfw.init():
        return

    glfw.window_hint(glfw.CONTEXT_VERSION_MAJOR, 3)
    glfw.window_hint(glfw.CONTEXT_VERSION_MINOR, 3)
    glfw.window_hint(glfw.OPENGL_FORWARD_COMPAT, GL_TRUE)
    glfw.window_hint(glfw.OPENGL_PROFILE, glfw.OPENGL_CORE_PROFILE)
    window = glfw.create_window(800, 600, "vbo test", None, None)

    if not window:
        glfw.terminate()
        return
    glfw.make_context_current(window)


    test = [0.5, -0.5, 0.0,        1.0, 0.0, 0.0,
            -0.5, -0.5, 0.0,      0.0, 1.0, 0.0,
            0.0,0.5, 0.0,       0.0, 0.0, 1.0 ]


    triangle = numpy.array(list(map(float,test)), dtype=numpy.float32)

    vertex_shader_source = """
                            #version 330 core
                            in vec3 vPosition;
                            in vec3 vColor;

                            out vec3 color;

                            uniform mat4 ModelViewProjectionMatrix;

                            void main()
                            {
                                color = vColor;

                                gl_Position = vec4(vPosition,1.0f) ;
                            }
                            """
    fragment_shader_cource = """
                            #version 330 core
                            in vec3 color;
                            
                            out vec4 outColor;
                            void main()
                            {
                                outColor = vec4(color,1.0f);
                            }
                             """

    VAO = glGenVertexArrays(1)
    glBindVertexArray(VAO)

    vertex_shader = shaders.compileShader(vertex_shader_source, GL_VERTEX_SHADER)
    fragment_shader = shaders.compileShader(fragment_shader_cource, GL_FRAGMENT_SHADER)
    shader = shaders.compileProgram(vertex_shader, fragment_shader)

    VBO = glGenBuffers(1)
    glBindBuffer(GL_ARRAY_BUFFER, VBO)
    glBufferData(GL_ARRAY_BUFFER, triangle.itemsize * triangle.size, triangle, GL_STATIC_DRAW)

    position = glGetAttribLocation(shader, "vPosition")
    glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, 4*6, ctypes.c_void_p(0))
    glEnableVertexAttribArray(position)

    color = glGetAttribLocation(shader,"vColor")
    glVertexAttribPointer(color,3,GL_FLOAT,GL_FALSE, 4*6, ctypes.c_void_p(4*3))
    glEnableVertexAttribArray(color)
    glUseProgram(0)
    glUseProgram(shader)
    glClearColor(0, 0, 0, 0)

    while not glfw.window_should_close(window):
        glfw.poll_events()

        glClear(GL_COLOR_BUFFER_BIT)

        glDrawArrays(GL_TRIANGLES, 0,3)


        glfw.swap_buffers(window)

    glfw.terminate()


if __name__ == "__main__":
    main()

Upvotes: 1

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