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

.. only:: html

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

        Click :ref:`here <sphx_glr_download_gallery_gloo_gl_fireworks.py>`
        to download the full example code

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

.. _sphx_glr_gallery_gloo_gl_fireworks.py:


Example demonstrating simulation of fireworks using point sprites
=================================================================

(adapted from the "OpenGL ES 2.0 Programming Guide")
This example demonstrates a series of explosions that last one second. The
visualization during the explosion is highly optimized using a Vertex Buffer
Object (VBO). After each explosion, vertex data for the next explosion are
calculated, such that each explostion is unique.

.. GENERATED FROM PYTHON SOURCE LINES 21-161







.. code-block:: default

    import numpy as np

    from vispy import app
    from vispy.gloo import gl


    vertex_code = """
    #version 120

    uniform float time;
    uniform vec3 center;
    attribute float lifetime;
    attribute vec3 start;
    attribute vec3 end;
    varying float v_lifetime;
    void main () {
        if (time < lifetime) {
            gl_Position.xyz = start + (time * end) + center;
            gl_Position.w = 1.0;
            gl_Position.y -= 1.5 * time * time;
        } else {
            gl_Position = vec4(-1000, -1000, 0, 0);
        }
        v_lifetime = clamp(1.0 - (time / lifetime), 0.0, 1.0);
        gl_PointSize = (v_lifetime * v_lifetime) * 40.0;
    }
    """

    fragment_code = """
    #version 120

    uniform vec4 color;
    varying float v_lifetime;
    void main()
    {
        float d = 1 - length(gl_PointCoord - vec2(.5,.5)) / (sqrt(2)/2);
        gl_FragColor = d*color;
        gl_FragColor.a = d;
        gl_FragColor.a *= v_lifetime;
    }
    """


    class Canvas(app.Canvas):
        def __init__(self):
            app.Canvas.__init__(self, size=(800, 600), title='GL Fireworks',
                                keys='interactive')

        def on_initialize(self, event):
            # Build & activate program
            self.program = gl.glCreateProgram()
            vertex = gl.glCreateShader(gl.GL_VERTEX_SHADER)
            fragment = gl.glCreateShader(gl.GL_FRAGMENT_SHADER)
            gl.glShaderSource(vertex, vertex_code)
            gl.glShaderSource(fragment, fragment_code)
            gl.glCompileShader(vertex)
            gl.glCompileShader(fragment)
            gl.glAttachShader(self.program, vertex)
            gl.glAttachShader(self.program, fragment)
            gl.glLinkProgram(self.program)
            gl.glDetachShader(self.program, vertex)
            gl.glDetachShader(self.program, fragment)
            gl.glUseProgram(self.program)

            # Build vertex buffer
            n = 10000
            self.data = np.zeros(n, dtype=[('lifetime', np.float32),
                                           ('start', np.float32, 3),
                                           ('end', np.float32, 3)])
            vbuffer = gl.glCreateBuffer()
            gl.glBindBuffer(gl.GL_ARRAY_BUFFER, vbuffer)
            gl.glBufferData(gl.GL_ARRAY_BUFFER, self.data, gl.GL_DYNAMIC_DRAW)

            # Bind buffer attributes
            stride = self.data.strides[0]

            offset = 0
            loc = gl.glGetAttribLocation(self.program, "lifetime")
            gl.glEnableVertexAttribArray(loc)
            gl.glVertexAttribPointer(loc, 1, gl.GL_FLOAT, False, stride, offset)

            offset = self.data.dtype["lifetime"].itemsize
            loc = gl.glGetAttribLocation(self.program, "start")
            gl.glEnableVertexAttribArray(loc)
            gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, stride, offset)

            offset = self.data.dtype["start"].itemsize
            loc = gl.glGetAttribLocation(self.program, "end")
            gl.glEnableVertexAttribArray(loc)
            gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, stride, offset)

            # OpenGL initalization
            self.elapsed_time = 0
            gl.glClearColor(0, 0, 0, 1)
            gl.glDisable(gl.GL_DEPTH_TEST)
            gl.glEnable(gl.GL_BLEND)
            gl.glBlendFunc(gl.GL_SRC_ALPHA, gl.GL_ONE)
            gl.glEnable(34370)  # gl.GL_VERTEX_PROGRAM_POINT_SIZE
            gl.glEnable(34913)  # gl.GL_POINT_SPRITE
            gl.glViewport(0, 0, *self.physical_size)
            self.new_explosion()
            self.timer = app.Timer('auto', self.on_timer, start=True)

        def on_draw(self, event):
            gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT)
            gl.glDrawArrays(gl.GL_POINTS, 0, len(self.data))

        def on_resize(self, event):
            gl.glViewport(0, 0, *event.physical_size)

        def on_timer(self, event):
            self.elapsed_time += 1. / 60.
            if self.elapsed_time > 1.5:
                self.new_explosion()
                self.elapsed_time = 0.0

            loc = gl.glGetUniformLocation(self.program, "time")
            gl.glUniform1f(loc, self.elapsed_time)
            self.update()

        def new_explosion(self):
            n = len(self.data)
            color = np.random.uniform(0.1, 0.9, 4).astype(np.float32)
            color[3] = 1.0 / n ** 0.08
            loc = gl.glGetUniformLocation(self.program, "color")
            gl.glUniform4f(loc, *color)

            center = np.random.uniform(-0.5, 0.5, 3)
            loc = gl.glGetUniformLocation(self.program, "center")
            gl.glUniform3f(loc, *center)

            self.data['lifetime'] = np.random.normal(2.0, 0.5, (n,))
            self.data['start'] = np.random.normal(0.0, 0.2, (n, 3))
            self.data['end'] = np.random.normal(0.0, 1.2, (n, 3))
            gl.glBufferData(gl.GL_ARRAY_BUFFER, self.data, gl.GL_DYNAMIC_DRAW)

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


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

   **Total running time of the script:** ( 0 minutes  0.139 seconds)


.. _sphx_glr_download_gallery_gloo_gl_fireworks.py:


.. only :: html

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



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

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



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

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


.. only:: html

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

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