# ----------------------------------------------------------------------------- # Python & OpenGL for Scientific Visualization # www.labri.fr/perso/nrougier/python+opengl # Copyright (c) 2018, Nicolas P. Rougier # Distributed under the 2-Clause BSD License. # ----------------------------------------------------------------------------- import sys import ctypes import numpy as np from glumpy import app, gloo, gl vertex = """ uniform vec2 resolution; uniform float antialias; uniform float thickness; uniform float linelength; attribute vec4 prev, curr, next; varying vec2 v_uv; void main() { float w = thickness/2.0 + antialias; vec2 p; if (prev.xy == curr.xy) { vec2 t1 = normalize(next.xy - curr.xy); vec2 n1 = vec2(-t1.y, t1.x); v_uv = vec2(-w, curr.z*w); p = curr.xy - w*t1 + curr.z*w*n1; } else if (curr.xy == next.xy) { vec2 t0 = normalize(curr.xy - prev.xy); vec2 n0 = vec2(-t0.y, t0.x); v_uv = vec2(linelength+w, curr.z*w); p = curr.xy + w*t0 + curr.z*w*n0; } else { vec2 t0 = normalize(curr.xy - prev.xy); vec2 t1 = normalize(next.xy - curr.xy); vec2 n0 = vec2(-t0.y, t0.x); vec2 n1 = vec2(-t1.y, t1.x); vec2 miter = normalize(n0 + n1); float dy = w / dot(miter, n1); v_uv = vec2(curr.w, curr.z*w); p = curr.xy + dy*curr.z*miter; } gl_Position = vec4(2.0*p/resolution-1.0, 0.0, 1.0); } """ fragment = """ uniform float antialias; uniform float thickness; uniform float linelength; varying vec2 v_uv; void main() { float d = 0; float w = thickness/2.0 - antialias; // Cap at start if (v_uv.x < 0) d = length(v_uv) - w; // Cap at end else if (v_uv.x >= linelength) d = length(v_uv - vec2(linelength,0)) - w; // Body else d = abs(v_uv.y) - w; if( d < 0) { gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0); } else { d /= antialias; gl_FragColor = vec4(0.0, 0.0, 0.0, exp(-d*d)); } } """ window = app.Window(2*512, 512, color=(1,1,1,1)) @window.event def on_resize(width, height): spiral["resolution"] = width, height star["resolution"] = width, height @window.event def on_draw(dt): window.clear() spiral.draw(gl.GL_TRIANGLE_STRIP) star.draw(gl.GL_TRIANGLE_STRIP) def star(inner=0.45, outer=1.0, n=5): R = np.array([inner,outer]*n) T = np.linspace(0, 2*np.pi, 2*n, endpoint=False) P = np.zeros((2*n,2)) P[:,0]= R*np.cos(T) P[:,1]= R*np.sin(T) return P def bake(P, closed=False): epsilon = 1e-10 n = len(P) if closed and ((P[0]-P[-1])**2).sum() > epsilon: P = np.append(P, P[0]) P = P.reshape(n+1,2) n = n+1 V = np.zeros(((1+n+1),2,4), dtype=np.float32) V_prev, V_curr, V_next = V[:-2], V[1:-1], V[2:] V_curr[...,0] = P[:,np.newaxis,0] V_curr[...,1] = P[:,np.newaxis,1] V_curr[...,2] = 1,-1 L = np.cumsum(np.sqrt(((P[1:]-P[:-1])**2).sum(axis=-1))).reshape(n-1,1) V_curr[1:,:,3] = L if closed: V[0], V[-1] = V[-3], V[2] else: V[0], V[-1] = V[1], V[-2] return V_prev, V_curr, V_next, L[-1] n = 1024 T = np.linspace(0, 12*2*np.pi, n, dtype=np.float32) R = np.linspace(10, 246, n, dtype=np.float32) P = np.dstack((256+np.cos(T)*R, 256+np.sin(T)*R)).squeeze() V_prev, V_curr, V_next, length = bake(P) spiral = gloo.Program(vertex, fragment) spiral["prev"], spiral["curr"], spiral["next"] = V_prev, V_curr, V_next spiral["thickness"] = 1.0 spiral["antialias"] = 1.5 spiral["linelength"] = length P = (star(n=5)*220 + (512+256,256)).astype(np.float32) V_prev, V_curr, V_next, length = bake(P, True) star = gloo.Program(vertex, fragment) star["prev"], star["curr"], star["next"] = V_prev, V_curr, V_next star["thickness"] = 32.0 star["antialias"] = 1.5 star["linelength"] = length app.run()