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local win = require("window")
local color = require("color")
local world = require("world")
local numstars = 400 -- we might have as many as 4 over
local genned_stars = 0
local period_x = 3
local period_y = 3
local stars = {}
while genned_stars < numstars do
local rngx = math.random()
local xpos = rngx * win.width --* (period_x - 1)
local rngy = math.random()
local ypos = rngy * win.height --* (period_y - 1)
local blinks = math.random() > 0.3 and (math.random() * 2 * math.pi) or 0
stars[#stars+1] = vec3(xpos, ypos, blinks)
genned_stars = genned_stars + 1
if xpos < win.width then
-- duplicate on the last screen
stars[#stars+1] = vec3(xpos + (win.width * (period_x-2)), ypos, blinks)
genned_stars = genned_stars + 1
end
if ypos < win.height then
stars[#stars+1] = vec3(xpos, ypos + (win.height * (period_y-2)), blinks)
genned_stars = genned_stars + 1
end
if xpos < win.width and ypos < win.height then
stars[#stars+1] = vec3(xpos + (win.width * (period_x-2)), ypos+(win.height * (period_y-2)),blinks)
genned_stars = genned_stars + 1
end
end
local node = am.use_program(am.program([[
precision highp float;
attribute vec3 stars;
uniform float time;
uniform float world_x;
uniform float world_y;
uniform float world_x_period;
uniform float world_y_period;
uniform mat4 MV;
uniform mat4 P;
void main() {
float world_x_off = mod(world_x, world_x_period);
float world_y_off = mod(world_y, world_y_period);
gl_Position = P * MV * vec4(stars.x - world_x_off, stars.y - world_y_off, 0.0, 1.0);
float intensity = sin(stars.z + time) * cos(time) + 1.;
gl_PointSize = pow(intensity, 2.) * stars.z * 0.3;
}
]],[[
precision mediump float;
uniform vec4 color;
void main() {
gl_FragColor = color;
}
]]))
^ am.bind({
MV = mat4(
1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
(-win.width / 2), (-win.height/2), 0, 1
),
color = color.am_color.highlight,
stars = am.vec3_array(stars),
world_x = am.current_time(),
world_x_period = (period_x - 2) * win.width,
world_y = am.current_time(),
world_y_period = (period_y - 2) * win.height,
time = am.current_time(),
})
^ am.draw("points")
node:action(function(self)
self("bind").time = am.current_time()
self("bind").world_x = world.world_x
self("bind").world_y = world.world_y
end)
return node
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