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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# -----------------------------------------------------------------------------
# Copyright (c) 2014, Nicolas P. Rougier. All Rights Reserved.
# Distributed under the (new) BSD License.
# -----------------------------------------------------------------------------
from vispy import app, gloo
vertex = """
attribute vec2 position;
void main()
{
gl_Position = vec4(position, 0.0, 1.0);
}
"""
fragment = """
#include "math/constants.glsl"
#include "arrows/arrows.glsl"
#include "antialias/antialias.glsl"
uniform vec2 iResolution;
uniform vec2 iMouse;
void main()
{
const float M_PI = 3.14159265358979323846;
const float SQRT_2 = 1.4142135623730951;
const float linewidth = 3.0;
const float antialias = 1.0;
const float rows = 32.0;
const float cols = 32.0;
float body = min(iResolution.x/cols, iResolution.y/rows) / SQRT_2;
vec2 texcoord = gl_FragCoord.xy;
vec2 size = iResolution.xy / vec2(cols,rows);
vec2 center = (floor(texcoord/size) + vec2(0.5,0.5)) * size;
texcoord -= center;
float theta = M_PI-atan(center.y-iMouse.y, center.x-iMouse.x);
float cos_theta = cos(theta);
float sin_theta = sin(theta);
texcoord = vec2(cos_theta*texcoord.x - sin_theta*texcoord.y,
sin_theta*texcoord.x + cos_theta*texcoord.y);
float d = arrow_stealth(texcoord, body, 0.25*body, linewidth, antialias);
gl_FragColor = filled(d, linewidth, antialias, vec4(0,0,0,1));
}
"""
canvas = app.Canvas(size=(2*512, 2*512), keys='interactive')
canvas.context.set_state(blend=True,
blend_func=('src_alpha', 'one_minus_src_alpha'),
blend_equation='func_add')
@canvas.connect
def on_draw(event):
gloo.clear('white')
program.draw('triangle_strip')
@canvas.connect
def on_resize(event):
program["iResolution"] = event.size
gloo.set_viewport(0, 0, event.size[0], event.size[1])
@canvas.connect
def on_mouse_move(event):
x, y = event.pos
program["iMouse"] = x, canvas.size[1] - y
canvas.update()
program = gloo.Program(vertex, fragment, count=4)
dx, dy = 1, 1
program['position'] = (-dx, -dy), (-dx, +dy), (+dx, -dy), (+dx, +dy)
program["iResolution"] = (2 * 512, 2 * 512)
program["iMouse"] = (0., 0.)
if __name__ == '__main__':
canvas.show()
app.run()
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