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        "%gui qt"
      ]
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        "\n# Example demonstrating simulation of fireworks using point sprites\n\n(adapted from the \"OpenGL ES 2.0 Programming Guide\")\nThis example demonstrates a series of explosions that last one second. The\nvisualization during the explosion is highly optimized using a Vertex Buffer\nObject (VBO). After each explosion, vertex data for the next explosion are\ncalculated, such that each explostion is unique.\n"
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      "source": [
        "import numpy as np\n\nfrom vispy import app\nfrom vispy.gloo import gl\n\n\nvertex_code = \"\"\"\n#version 120\n\nuniform float time;\nuniform vec3 center;\nattribute float lifetime;\nattribute vec3 start;\nattribute vec3 end;\nvarying float v_lifetime;\nvoid main () {\n    if (time < lifetime) {\n        gl_Position.xyz = start + (time * end) + center;\n        gl_Position.w = 1.0;\n        gl_Position.y -= 1.5 * time * time;\n    } else {\n        gl_Position = vec4(-1000, -1000, 0, 0);\n    }\n    v_lifetime = clamp(1.0 - (time / lifetime), 0.0, 1.0);\n    gl_PointSize = (v_lifetime * v_lifetime) * 40.0;\n}\n\"\"\"\n\nfragment_code = \"\"\"\n#version 120\n\nuniform vec4 color;\nvarying float v_lifetime;\nvoid main()\n{\n    float d = 1 - length(gl_PointCoord - vec2(.5,.5)) / (sqrt(2)/2);\n    gl_FragColor = d*color;\n    gl_FragColor.a = d;\n    gl_FragColor.a *= v_lifetime;\n}\n\"\"\"\n\n\nclass Canvas(app.Canvas):\n    def __init__(self):\n        app.Canvas.__init__(self, size=(800, 600), title='GL Fireworks',\n                            keys='interactive')\n\n    def on_initialize(self, event):\n        # Build & activate program\n        self.program = gl.glCreateProgram()\n        vertex = gl.glCreateShader(gl.GL_VERTEX_SHADER)\n        fragment = gl.glCreateShader(gl.GL_FRAGMENT_SHADER)\n        gl.glShaderSource(vertex, vertex_code)\n        gl.glShaderSource(fragment, fragment_code)\n        gl.glCompileShader(vertex)\n        gl.glCompileShader(fragment)\n        gl.glAttachShader(self.program, vertex)\n        gl.glAttachShader(self.program, fragment)\n        gl.glLinkProgram(self.program)\n        gl.glDetachShader(self.program, vertex)\n        gl.glDetachShader(self.program, fragment)\n        gl.glUseProgram(self.program)\n\n        # Build vertex buffer\n        n = 10000\n        self.data = np.zeros(n, dtype=[('lifetime', np.float32),\n                                       ('start', np.float32, 3),\n                                       ('end', np.float32, 3)])\n        vbuffer = gl.glCreateBuffer()\n        gl.glBindBuffer(gl.GL_ARRAY_BUFFER, vbuffer)\n        gl.glBufferData(gl.GL_ARRAY_BUFFER, self.data, gl.GL_DYNAMIC_DRAW)\n\n        # Bind buffer attributes\n        stride = self.data.strides[0]\n\n        offset = 0\n        loc = gl.glGetAttribLocation(self.program, \"lifetime\")\n        gl.glEnableVertexAttribArray(loc)\n        gl.glVertexAttribPointer(loc, 1, gl.GL_FLOAT, False, stride, offset)\n\n        offset = self.data.dtype[\"lifetime\"].itemsize\n        loc = gl.glGetAttribLocation(self.program, \"start\")\n        gl.glEnableVertexAttribArray(loc)\n        gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, stride, offset)\n\n        offset = self.data.dtype[\"start\"].itemsize\n        loc = gl.glGetAttribLocation(self.program, \"end\")\n        gl.glEnableVertexAttribArray(loc)\n        gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, stride, offset)\n\n        # OpenGL initalization\n        self.elapsed_time = 0\n        gl.glClearColor(0, 0, 0, 1)\n        gl.glDisable(gl.GL_DEPTH_TEST)\n        gl.glEnable(gl.GL_BLEND)\n        gl.glBlendFunc(gl.GL_SRC_ALPHA, gl.GL_ONE)\n        gl.glEnable(34370)  # gl.GL_VERTEX_PROGRAM_POINT_SIZE\n        gl.glEnable(34913)  # gl.GL_POINT_SPRITE\n        gl.glViewport(0, 0, *self.physical_size)\n        self.new_explosion()\n        self.timer = app.Timer('auto', self.on_timer, start=True)\n\n    def on_draw(self, event):\n        gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT)\n        gl.glDrawArrays(gl.GL_POINTS, 0, len(self.data))\n\n    def on_resize(self, event):\n        gl.glViewport(0, 0, *event.physical_size)\n\n    def on_timer(self, event):\n        self.elapsed_time += 1. / 60.\n        if self.elapsed_time > 1.5:\n            self.new_explosion()\n            self.elapsed_time = 0.0\n\n        loc = gl.glGetUniformLocation(self.program, \"time\")\n        gl.glUniform1f(loc, self.elapsed_time)\n        self.update()\n\n    def new_explosion(self):\n        n = len(self.data)\n        color = np.random.uniform(0.1, 0.9, 4).astype(np.float32)\n        color[3] = 1.0 / n ** 0.08\n        loc = gl.glGetUniformLocation(self.program, \"color\")\n        gl.glUniform4f(loc, *color)\n\n        center = np.random.uniform(-0.5, 0.5, 3)\n        loc = gl.glGetUniformLocation(self.program, \"center\")\n        gl.glUniform3f(loc, *center)\n\n        self.data['lifetime'] = np.random.normal(2.0, 0.5, (n,))\n        self.data['start'] = np.random.normal(0.0, 0.2, (n, 3))\n        self.data['end'] = np.random.normal(0.0, 1.2, (n, 3))\n        gl.glBufferData(gl.GL_ARRAY_BUFFER, self.data, gl.GL_DYNAMIC_DRAW)\n\nif __name__ == '__main__':\n    c = Canvas()\n    c.show()\n    app.run()"
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