WebGL backend demo

In [ ]:

    

import numpy as np
import vispy
import vispy.gloo as gloo
from vispy import app
from vispy.util.transforms import perspective, translate, rotate

# load the vispy bindings for the IPython notebook which enables webGL
%load_ext vispy.ipython


    

In [ ]:

    

n = 100
a_position = np.random.uniform(-1, 1, (n, 3)).astype(np.float32)
a_id = np.random.randint(0, 30, (n, 1))
a_id = np.sort(a_id, axis=0).astype(np.float32)


    

In [ ]:

    

VERT_SHADER = """
uniform mat4 u_model;
uniform mat4 u_view;
uniform mat4 u_projection;
attribute vec3 a_position;
attribute float a_id;
varying float v_id;
void main (void) {
    v_id = a_id;
    gl_Position = u_projection * u_view * u_model * vec4(a_position,1.0);
}
"""

FRAG_SHADER = """
varying float v_id;
void main()
{
    float f = fract(v_id);
    // The second useless test is needed on OSX 10.8 (fuck)
    if( (f > 0.0001) && (f < .9999) )
        discard;
    else
        gl_FragColor = vec4(0,0,0,1);
}
"""


    

In [ ]:

    

class Canvas(app.Canvas):

    # ---------------------------------
    def __init__(self, size=None):
        app.Canvas.__init__(self, keys='interactive', size=size)

        self.program = gloo.Program(VERT_SHADER, FRAG_SHADER)

        # Set uniform and attribute
        self.program['a_id'] = gloo.VertexBuffer(a_id)
        self.program['a_position'] = gloo.VertexBuffer(a_position)

        self.translate = 5
        self.view = translate((0, 0, -self.translate), dtype=np.float32)
        self.model = np.eye(4, dtype=np.float32)

        gloo.set_viewport(0, 0, self.physical_size[0], self.physical_size[1])
        self.projection = perspective(45.0, self.size[0] /
                                      float(self.size[1]), 1.0, 1000.0)
        self.program['u_projection'] = self.projection

        self.program['u_model'] = self.model
        self.program['u_view'] = self.view

        self.theta = 0
        self.phi = 0

        self.context.set_clear_color('white')
        self.context.set_state('translucent')

        self.timer = app.Timer('auto', connect=self.on_timer, start=True)

        self.show()

    # ---------------------------------
    def on_key_press(self, event):
        if event.text == ' ':
            if self.timer.running:
                self.timer.stop()
            else:
                self.timer.start()

    # ---------------------------------
    def on_timer(self, event):
        self.theta += .5
        self.phi += .5
        self.model = np.dot(rotate(self.theta, (0, 0, 1)),
                            rotate(self.phi, (0, 1, 0)))
        self.program['u_model'] = self.model
        self.update()

    # ---------------------------------
    def on_resize(self, event):
        gloo.set_viewport(0, 0, event.physical_size[0], event.physical_size[1])
        self.projection = perspective(45.0, event.size[0] /
                                      float(event.size[1]), 1.0, 1000.0)
        self.program['u_projection'] = self.projection

    # ---------------------------------
    def on_mouse_wheel(self, event):
        self.translate += event.delta[1]
        self.translate = max(2, self.translate)
        self.view = translate((0, 0, -self.translate))
        self.program['u_view'] = self.view
        self.update()

    # ---------------------------------
    def on_draw(self, event):
        self.context.clear()
        self.program.draw('line_strip')


    

In [ ]:

    

c = Canvas(size=(300, 300))
#or
#from vispy.app.backends.ipython import VispyWidget
#w = VispyWidget()
#w.set_canvas(c)
#w


    

In [ ]:

    

#c.timer.stop()