1 files changed, 76 insertions, 0 deletions
diff --git a/src/shaders/stars.lua b/src/shaders/stars.lua
new file mode 100644
index 0000000..111bef8
--- /dev/null
+++ b/src/shaders/stars.lua
@@ -0,0 +1,76 @@
+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