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"""shader_noise shader function and texture generator
as described in "GPU Gems" chapter 5:
http://http.developer.nvidia.com/GPUGems/gpugems_ch05.html
"""
__version__ = "$Id: shader_noise.py 37 2008-06-27 22:25:39Z casey.duncan $"
from noise import pnoise3
import ctypes
from pyglet.gl import *
class ShaderNoiseTexture:
"""tiling 3D noise texture with two channels for use by the
shader noise functions.
"""
def __init__(self, freq=8, width=32):
"""Generate the 3D noise texture.
freq -- frequency of generated noise over the width of the
texture.
width -- Width of the texture in texels. The texture is cubic,
thus all sides are the same width. Must be a power of two.
Using a larger width can reduce artifacts caused by linear
interpolation of the noise texture, at the cost of video
memory, and possibly slower texture access.
"""
self.freq = freq
self.width = width
scale = float(freq) / width
width2 = width**2
texel = (ctypes.c_ushort * (2 * width**3))()
for z in range(width):
for y in range(width):
for x in range(width):
texel[(x + (y * width) + (z * width2)) * 2] = int((pnoise3(
x * scale, y * scale, z * scale,
repeatx=freq, repeaty=freq, repeatz=freq) + 1.0) * 32767)
texel[(x + (y * width) + (z * width2)) * 2 + 1] = int((pnoise3(
x * scale, y * scale, z * scale,
repeatx=freq, repeaty=freq, repeatz=freq, base=freq + 1) + 1.0) * 32767)
self.data = texel
def load(self):
"""Load the noise texture data into the current texture unit"""
glTexImage3D(GL_TEXTURE_3D, 0, GL_LUMINANCE16_ALPHA16,
self.width, self.width, self.width, 0, GL_LUMINANCE_ALPHA,
GL_UNSIGNED_SHORT, ctypes.byref(self.data))
def enable(self):
"""Convenience method to enable 3D texturing state so the texture may be used by the
ffpnoise shader function
"""
glEnable(GL_TEXTURE_3D)
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_REPEAT)
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_REPEAT)
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
shader_noise_glsl = '''
/*
* GLSL Shader functions for fast fake Perlin 3D noise
*
* The required shader_noise_tex texture can be generated using the
* ShaderNoiseTexture class. It is a toroidal tiling 3D texture with each texel
* containing two 16-bit noise source channels. The shader permutes the source
* texture values by combining the channels such that the noise repeats at a
* much larger interval than the input texture.
*/
uniform sampler3D shader_noise_tex;
const float twopi = 3.1415926 * 2.0;
/* Simple perlin noise work-alike */
float
pnoise(vec3 position)
{
vec4 hi = 2.0 * texture3D(shader_noise_tex, position.xyz) - 1.0;
vec4 lo = 2.0 * texture3D(shader_noise_tex, position.xyz / 9.0) - 1.0;
return hi.r * cos(twopi * lo.r) + hi.a * sin(twopi * lo.r);
}
/* Multi-octave fractal brownian motion perlin noise */
float
fbmnoise(vec3 position, int octaves)
{
float m = 1.0;
vec3 p = position;
vec4 hi = vec4(0.0);
/* XXX Loops may not work correctly on all video cards */
for (int x = 0; x < octaves; x++) {
hi += (2.0 * texture3D(shader_noise_tex, p.xyz) - 1.0) * m;
p *= 2.0;
m *= 0.5;
}
vec4 lo = 2.0 * texture3D(shader_noise_tex, position.xyz / 9.0) - 1.0;
return hi.r * cos(twopi * lo.r) + hi.a * sin(twopi * lo.r);
}
/* Multi-octave turbulent noise */
float
fbmturbulence(vec3 position, int octaves)
{
float m = 1.0;
vec3 p = position;
vec4 hi = vec4(0.0);
/* XXX Loops may not work correctly on all video cards */
for (int x = 0; x < octaves; x++) {
hi += abs(2.0 * texture3D(shader_noise_tex, p.xyz) - 1.0) * m;
p *= 2.0;
m *= 0.5;
}
vec4 lo = texture3D(shader_noise_tex, position.xyz / 9.0);
return 2.0 * mix(hi.r, hi.a, cos(twopi * lo.r) * 0.5 + 0.5) - 1.0;
}
'''
if __name__ == '__main__':
# Demo using a simple noise-textured rotating sphere
import shader
win = pyglet.window.Window(width=640, height=640, resizable=True, visible=False)
vert_shader = shader.VertexShader('stupid', '''
/* simple vertex shader that stores the vertex position in a varying
* for easy access by the frag shader
*/
varying vec3 position;
void main(void) {
position = gl_Vertex.xyz * 5.0;
gl_Position = ftransform();
}
''')
frag_shader = shader.FragmentShader('noise_test', shader_noise_glsl + '''
varying vec3 position;
void main(void) {
float v;
float a = atan(position.y, position.x);
float arc = 3.14159 / 3.0;
if (a > -arc && a < arc) {
v = pnoise(position) * 0.5 + 0.5;
} else if (a > arc && a < arc * 4.0) {
v = fbmnoise(position, 4) * 0.5 + 0.5;
} else {
v = fbmturbulence(position, 4) * 0.5 + 0.5;
}
gl_FragColor = vec4(v, v, v, 1.0);
}
''')
shader_prog = shader.ShaderProgram(vert_shader, frag_shader)
shader_prog.install()
tex = ShaderNoiseTexture()
tex.load()
tex.enable()
shader_prog.uset1I('shader_noise_tex', 0)
quadratic = gluNewQuadric()
gluQuadricNormals(quadratic, GLU_SMOOTH)
gluQuadricTexture(quadratic, GL_TRUE)
glEnable(GL_CULL_FACE)
global spin
spin = 0
def on_resize(width, height):
glViewport(0, 0, width, height)
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
gluPerspective(70, 1.0*width/height, 0.1, 1000.0)
glMatrixMode(GL_MODELVIEW)
glLoadIdentity()
win.on_resize = on_resize
@win.event
def on_draw():
global spin
win.clear()
glLoadIdentity()
glTranslatef(0, 0, -1.5)
glRotatef(spin, 1.0, 1.0, 1.0)
gluSphere(quadratic, 0.65, 60, 60)
def update(dt):
global spin
spin += dt * 10.0
pyglet.clock.schedule_interval(update, 1.0/30.0)
win.set_visible()
pyglet.app.run()
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