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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# vispy: gallery 4:30:2
"""
Show an Image
=============
Draw a new array of random image pixels on every draw cycle.
"""
import numpy as np
from vispy.util.transforms import ortho
from vispy import gloo
from vispy import app
# Image to be displayed
W, H = 64, 48
img_array = np.random.uniform(0, 1, (W, H)).astype(np.float32)
# A simple texture quad
data = np.zeros(4, dtype=[('a_position', np.float32, 2),
('a_texcoord', np.float32, 2)])
data['a_position'] = np.array([[0, 0], [W, 0], [0, H], [W, H]])
data['a_texcoord'] = np.array([[0, 0], [0, 1], [1, 0], [1, 1]])
VERT_SHADER = """
// Uniforms
uniform mat4 u_model;
uniform mat4 u_view;
uniform mat4 u_projection;
uniform float u_antialias;
// Attributes
attribute vec2 a_position;
attribute vec2 a_texcoord;
// Varyings
varying vec2 v_texcoord;
// Main
void main (void)
{
v_texcoord = a_texcoord;
gl_Position = u_projection * u_view * u_model * vec4(a_position,0.0,1.0);
}
"""
FRAG_SHADER = """
uniform sampler2D u_texture;
varying vec2 v_texcoord;
void main()
{
gl_FragColor = texture2D(u_texture, v_texcoord);
gl_FragColor.a = 1.0;
}
"""
class Canvas(app.Canvas):
def __init__(self):
app.Canvas.__init__(self, keys='interactive', size=((W * 5), (H * 5)))
self.program = gloo.Program(VERT_SHADER, FRAG_SHADER)
self.texture = gloo.Texture2D(img_array, interpolation='linear')
self.program['u_texture'] = self.texture
self.program.bind(gloo.VertexBuffer(data))
self.view = np.eye(4, dtype=np.float32)
self.model = np.eye(4, dtype=np.float32)
self.projection = np.eye(4, dtype=np.float32)
self.program['u_model'] = self.model
self.program['u_view'] = self.view
self.projection = ortho(0, W, 0, H, -1, 1)
self.program['u_projection'] = self.projection
gloo.set_clear_color('white')
self._timer = app.Timer('auto', connect=self.update, start=True)
self.show()
def on_resize(self, event):
width, height = event.physical_size
gloo.set_viewport(0, 0, width, height)
self.projection = ortho(0, width, 0, height, -100, 100)
self.program['u_projection'] = self.projection
# Compute thje new size of the quad
r = width / float(height)
R = W / float(H)
if r < R:
w, h = width, width / R
x, y = 0, int((height - h) / 2)
else:
w, h = height * R, height
x, y = int((width - w) / 2), 0
data['a_position'] = np.array(
[[x, y], [x + w, y], [x, y + h], [x + w, y + h]])
self.program.bind(gloo.VertexBuffer(data))
def on_draw(self, event):
gloo.clear(color=True, depth=True)
img_array[...] = np.random.uniform(0, 1, (W, H)).astype(np.float32)
self.texture.set_data(img_array)
self.program.draw('triangle_strip')
if __name__ == '__main__':
canvas = Canvas()
app.run()
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