.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/gloo/post_processing.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_gallery_gloo_post_processing.py>`
        to download the full example code

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_gloo_post_processing.py:


Show post-processing using a FrameBuffer
========================================

.. GENERATED FROM PYTHON SOURCE LINES 17-160



.. image-sg:: /gallery/gloo/images/sphx_glr_post_processing_001.gif
   :alt: post processing
   :srcset: /gallery/gloo/images/sphx_glr_post_processing_001.gif
   :class: sphx-glr-single-img





.. code-block:: Python


    import numpy as np
    from vispy import app

    from vispy.geometry import create_cube
    from vispy.util.transforms import perspective, translate, rotate
    from vispy.gloo import (Program, VertexBuffer, IndexBuffer, Texture2D, clear,
                            FrameBuffer, RenderBuffer, set_viewport, set_state)


    cube_vertex = """
    uniform mat4 model;
    uniform mat4 view;
    uniform mat4 projection;
    attribute vec3 position;
    attribute vec2 texcoord;
    attribute vec3 normal;  // not used in this example
    attribute vec4 color;  // not used in this example
    varying vec2 v_texcoord;
    void main()
    {
        gl_Position = projection * view * model * vec4(position,1.0);
        v_texcoord = texcoord;
    }
    """

    cube_fragment = """
    uniform sampler2D texture;
    varying vec2 v_texcoord;
    void main()
    {
        float r = texture2D(texture, v_texcoord).r;
        gl_FragColor = vec4(r,r,r,1);
    }
    """

    quad_vertex = """
    attribute vec2 position;
    attribute vec2 texcoord;
    varying vec2 v_texcoord;
    void main()
    {
        gl_Position = vec4(position, 0.0, 1.0);
        v_texcoord = texcoord;
    }
    """

    quad_fragment = """
    uniform sampler2D texture;
    varying vec2 v_texcoord;
    void main()
    {
        vec2 d = 5.0 * vec2(sin(v_texcoord.y*50.0),0)/512.0;

        // Inverse video
        if( v_texcoord.x > 0.5 ) {
            gl_FragColor.rgb = 1.0-texture2D(texture, v_texcoord+d).rgb;
        } else {
            gl_FragColor = texture2D(texture, v_texcoord);
        }
    }
    """


    def checkerboard(grid_num=8, grid_size=32):
        row_even = grid_num // 2 * [0, 1]
        row_odd = grid_num // 2 * [1, 0]
        Z = np.row_stack(grid_num // 2 * (row_even, row_odd)).astype(np.uint8)
        return 255 * Z.repeat(grid_size, axis=0).repeat(grid_size, axis=1)


    class Canvas(app.Canvas):

        def __init__(self):
            app.Canvas.__init__(self, title='Framebuffer post-processing',
                                keys='interactive', size=(512, 512))

            # Build cube data
            # --------------------------------------
            vertices, indices, _ = create_cube()
            vertices = VertexBuffer(vertices)
            self.indices = IndexBuffer(indices)

            # Build program
            # --------------------------------------
            view = translate((0, 0, -7))
            self.phi, self.theta = 60, 20
            model = rotate(self.theta, (0, 0, 1)).dot(rotate(self.phi, (0, 1, 0)))

            self.cube = Program(cube_vertex, cube_fragment)
            self.cube.bind(vertices)
            self.cube["texture"] = checkerboard()
            self.cube["texture"].interpolation = 'linear'
            self.cube['model'] = model
            self.cube['view'] = view

            color = Texture2D((512, 512, 3), interpolation='linear')
            self.framebuffer = FrameBuffer(color, RenderBuffer((512, 512)))

            self.quad = Program(quad_vertex, quad_fragment, count=4)
            self.quad['texcoord'] = [(0, 0), (0, 1), (1, 0), (1, 1)]
            self.quad['position'] = [(-1, -1), (-1, +1), (+1, -1), (+1, +1)]
            self.quad['texture'] = color

            # OpenGL and Timer initalization
            # --------------------------------------
            set_state(clear_color=(.3, .3, .35, 1), depth_test=True)
            self.timer = app.Timer('auto', connect=self.on_timer, start=True)
            self._set_projection(self.physical_size)

            self.show()

        def on_draw(self, event):
            with self.framebuffer:
                set_viewport(0, 0, 512, 512)
                clear(color=True, depth=True)
                set_state(depth_test=True)
                self.cube.draw('triangles', self.indices)
            set_viewport(0, 0, *self.physical_size)
            clear(color=True)
            set_state(depth_test=False)
            self.quad.draw('triangle_strip')

        def on_resize(self, event):
            self._set_projection(event.physical_size)

        def _set_projection(self, size):
            width, height = size
            set_viewport(0, 0, width, height)
            projection = perspective(30.0, width / float(height), 2.0, 10.0)
            self.cube['projection'] = projection

        def on_timer(self, event):
            self.theta += .5
            self.phi += .5
            model = rotate(self.theta, (0, 0, 1)).dot(rotate(self.phi, (0, 1, 0)))
            self.cube['model'] = model
            self.update()


    if __name__ == '__main__':
        canvas = Canvas()
        app.run()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 1.062 seconds)


.. _sphx_glr_download_gallery_gloo_post_processing.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: post_processing.ipynb <post_processing.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: post_processing.py <post_processing.py>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_