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"""
A Game of Life implementation using transform feedback.
We calculate the next state of the map with transform()
meaning a vertex shader will generate the new state into a buffer.
This buffer is then written into the texture we display.
This is a fast vram to vram copy.
Comments:
Another way to do this is simply rendering to Framebuffers.
"""
import numpy as np
import moderngl
from _example import Example
class Conway(Example):
title = "Conway's Game of Life"
window_size = 800, 800
def __init__(self, **kwargs):
super().__init__(**kwargs)
# How often the map should be updated
self.update_delay = 1 / 60 # updates per second
self.last_updated = 0
# size of the map
self.width, self.height = 400, 400
# Force the window to calculate black borders if needed to retain the aspect ratio
self.wnd.fixed_aspect_ratio = self.width / self.height
# Initial state of the map (random)
pixels = np.round(np.random.rand(self.width, self.height)).astype('f4')
# Program drawing the result to the screen.
# This is rendered simply using a textured screen aligned triangle strip
self.display_prog = self.ctx.program(
vertex_shader='''
#version 330
in vec2 in_vert;
in vec2 in_texcoord;
out vec2 v_text;
void main() {
v_text = in_texcoord;
gl_Position = vec4(in_vert, 0.0, 1.0);
}
''',
fragment_shader='''
#version 330
// Will read from texture bound to channel / locaton 0 by default
uniform sampler2D Texture;
// Interpolated texture coordinate from vertex shader
in vec2 v_text;
// The fragment ending up on the screen
out vec4 f_color;
void main() {
f_color = texture(Texture, v_text);
}
''',
)
# Program calculating the next state of the map
self.transform_prog = self.ctx.program(
vertex_shader='''
#version 330
uniform sampler2D Texture;
out float out_vert;
#define LIVING 0.0
#define DEAD 1.0
bool cell(int x, int y) {
// get the texture size
ivec2 tSize = textureSize(Texture, 0).xy;
// Ensure lookups are not going outside the texture area because
// texelFetch do not support texture repeat / wrap modes
return texelFetch(Texture, ivec2((x + tSize.x) % tSize.x, (y + tSize.y) % tSize.y), 0).r < 0.5;
}
void main() {
int width = textureSize(Texture, 0).x;
ivec2 in_text = ivec2(gl_VertexID % width, gl_VertexID / width);
bool living = cell(in_text.x, in_text.y);
int neighbours = 0;
if (cell(in_text.x - 1, in_text.y - 1)) neighbours++;
if (cell(in_text.x - 1, in_text.y + 0)) neighbours++;
if (cell(in_text.x - 1, in_text.y + 1)) neighbours++;
if (cell(in_text.x + 1, in_text.y - 1)) neighbours++;
if (cell(in_text.x + 1, in_text.y + 0)) neighbours++;
if (cell(in_text.x + 1, in_text.y + 1)) neighbours++;
if (cell(in_text.x + 0, in_text.y + 1)) neighbours++;
if (cell(in_text.x + 0, in_text.y - 1)) neighbours++;
if (living) {
out_vert = (neighbours == 2 || neighbours == 3) ? LIVING : DEAD;
} else {
out_vert = (neighbours == 3) ? LIVING : DEAD;
}
}
''',
varyings=['out_vert']
)
# Create the map texture
self.texture = self.ctx.texture((self.width, self.height), 1, pixels.tobytes(), dtype='f4')
self.texture.filter = moderngl.NEAREST, moderngl.NEAREST
self.texture.swizzle = 'RRR1' # What components texelFetch will get from the texture (in shader)
# A quad covering the screen with texture coordinates
self.vbo = self.ctx.buffer(np.array([
# x y u v
-1.0, -1.0, 0, 0, # lower left
-1.0, 1.0, 0, 1, # upper left
1.0, -1.0, 1, 0, # lower right
1.0, 1.0, 1, 1, # upper right
], dtype="f4"))
self.vao = self.ctx.vertex_array(self.display_prog, [self.vbo.bind('in_vert', 'in_texcoord')])
# Transform vertex array to generate new map state
self.tao = self.ctx.vertex_array(self.transform_prog, [])
self.pbo = self.ctx.buffer(reserve=pixels.nbytes) # buffer to store the result
def render(self, time, frame_time):
self.ctx.clear(1.0, 1.0, 1.0)
# Bind texture to channel 0
self.texture.use(location=0)
if time - self.last_updated > self.update_delay:
# Generate the new map and write that to the pbo buffer
self.tao.transform(self.pbo, vertices=self.width * self.height)
# Copy the pbo into the texture
self.texture.write(self.pbo)
self.last_updated = time
# Render the texture
self.vao.render(moderngl.TRIANGLE_STRIP)
if __name__ == '__main__':
Conway.run()
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