gloo-trail.py

# -----------------------------------------------------------------------------
# Copyright (c) 2009-2016 Nicolas P. Rougier. All rights reserved.
# Distributed under the (new) BSD License.
# -----------------------------------------------------------------------------
import sys
import numpy as np

import glumpy
import glumpy.gl as gl
import glumpy.app as app
import glumpy.glm as glm
import glumpy.gloo as gloo


vertex = """
#version 120

uniform mat4  u_projection;
uniform float u_linewidth;
uniform float u_antialias;

attribute vec3  a_position;
attribute vec4  a_fg_color;
attribute float a_size;

varying vec4  v_fg_color;
varying float v_size;

void main (void)
{
    v_size = a_size;
    v_fg_color = a_fg_color;
    if( a_fg_color.a > 0.0)
    {
        gl_Position = u_projection * vec4(a_position,1.0);
        gl_PointSize = v_size + u_linewidth + 2*1.5*u_antialias;
    }
    else
    {
        gl_Position = u_projection * vec4(-1,-1,0,1);
        gl_PointSize = 0.0;
    }
}
"""

fragment = """
#version 120

uniform float u_linewidth;
uniform float u_antialias;
varying vec4 v_fg_color;
varying vec4 v_bg_color;
varying float v_size;
float disc(vec2 P, float size)
{
    return length((P.xy - vec2(0.5,0.5))*size);
}
void main()
{
    if( v_fg_color.a <= 0.0)
        discard;
    float actual_size = v_size + u_linewidth + 2*1.5*u_antialias;
    float t = u_linewidth/2.0 - u_antialias;
    float r = disc(gl_PointCoord, actual_size);
    float d = abs(r - v_size/2.0) - t;
    if( d < 0.0 )
    {
         gl_FragColor = v_fg_color;
    }
    else if( abs(d) > 2.5*u_antialias )
    {
         discard;
    }
    else
    {
        d /= u_antialias;
        gl_FragColor = vec4(v_fg_color.rgb, exp(-d*d)*v_fg_color.a);
    }
}
"""


window = app.Window(width=800, height=800,
                    color=(0.2, 0.2, 0.2, 1.0))

@window.event
def on_draw(dt):
    window.clear()
    program.draw(gl.GL_POINTS)

@window.event
def on_resize(width, height):
    program['u_projection'] = glm.ortho(0, width, 0, height, -1, +1)

@window.timer(1/60.)
def timer(fps):
    data['a_fg_color'][..., 3] -= 0.01
    data['a_size'] += 1.0

@window.event
def on_mouse_motion(x, y, dx, dy):
    global index
    _, _, _, h = gl.glGetInteger(gl.GL_VIEWPORT)
    data['a_size'][index] = 25
    data['a_position'][index] = x, h - y
    data['a_fg_color'][index] = 1, 1, 1, 1
    index = (index + 1) % len(data)

data = np.zeros(150, [('a_position', np.float32, 2),
                      ('a_fg_color', np.float32, 4),
                      ('a_size',     np.float32, 1)])
data = data.view(gloo.VertexBuffer)

index = 0
program = gloo.Program(vertex, fragment)
program.bind(data)
program['u_antialias'] = 1.00
program['u_linewidth'] = 1.00

app.run(framerate=60)