1 files changed, 75 insertions, 11 deletions
diff --git a/bin/main.lua b/bin/main.lua
index 67c6122..789dcc6 100644
--- a/bin/main.lua
+++ b/bin/main.lua
@@ -43,15 +43,81 @@ vec4 effect(vec4 color, Image texture, vec2 texture_coords, vec2 pixel_coords)
 }	
 ]] 
 
+local lighningShader = [[ 
+extern vec2 iResolution; // 分辨率, pixels
+extern number iTime;  // 秒数, seconds
+// Lightning shader
+// rand,noise,fmb functions from https://www.shadertoy.com/view/Xsl3zN
+// jerome
+
+float rand(vec2 n) {
+    return fract(sin(dot(n, vec2(12.9898, 4.1414))) * 43758.5453);
+}
+
+float noise(vec2 n) {
+    const vec2 d = vec2(0.0, 1.0);
+    vec2 b = floor(n), f = smoothstep(vec2(0.0), vec2(1.0), fract(n));
+    return mix(mix(rand(b), rand(b + d.yx), f.x), mix(rand(b + d.xy), rand(b + d.yy), f.x), f.y);
+}
+
+float fbm(vec2 n) {
+    float total = 0.0, amplitude = 1.0;
+    for (int i = 0; i < 7; i++) {
+        total += noise(n) * amplitude;
+        n += n;
+        amplitude *= 0.5;
+    }
+    return total;
+}
+
+vec4 effect(vec4 outcolor, Image img, vec2 texture_coords, vec2 pixel_coords)
+//void mainImage( out vec4 fragColor, in vec2 fragCoord )
+{
+    vec4 col = vec4(0,0,0,1);
+    vec2 uv = pixel_coords.xy * 1.0 / iResolution.xy;
+   
+   
+    // draw a line, left side is fixed
+    vec2 t = uv * vec2(2.0,1.0) - iTime*3.0;
+    vec2 t2 = (vec2(1,-1) + uv) * vec2(2.0,1.0) - iTime*3.0; // a second strand
+   
+    // draw the lines,
+//  this make the left side fixed, can be useful
+//  float ycenter = mix( 0.5, 0.25 + 0.25*fbm( t ), uv.x*4.0);
+//    float ycenter2 = mix( 0.5, 0.25 + 0.25*fbm( t2 ), uv.x*4.0);
+    float ycenter = fbm(t)*0.5;
+    float ycenter2= fbm(t2)*0.5;
+
+    // falloff
+    float diff = abs(uv.y - ycenter);
+    float c1 = 1.0 - mix(0.0,1.0,diff*20.0);
+   
+    float diff2 = abs(uv.y - ycenter2);
+    float c2 = 1.0 - mix(0.0,1.0,diff2*20.0);
+   
+    float c = max(c1,c2);
+    col = vec4(c*0.6,0.2*c2,c,1.0); // purple color
+    //fragColor = col;
+	return col; 
+}
+]]
+
 local jg = jin.graphics
 local effect =  jg.Shader(shader) 
 local effect2 = jg.Shader(shader2)
+local lightning = jg.Shader(lighningShader)
 local diffuse = jg.Image("treestump_diffuse.png")
 local img = jg.Image("treestump.png")
+local img2 = jg.Image("lightning.png")
 local ww, wh = jg.size() 
 local scale = 2 
 ww = ww / scale 
 wh = wh / scale 
+jin.core.onLoad = function() 
+	jg.use(lightning)
+	lightning:send("vec2", "iResolution", ww, wh)
+	jg.unuse()
+end 
 jin.core.onEvent = function(e) 
 	if e.type == "quit" then 
 		jin.core.quit() 
@@ -59,7 +125,9 @@ jin.core.onEvent = function(e)
 end 
 local mx, my 
 local c = 0
+local t = 0;
 jin.core.onUpdate = function(dt) 
+	t = t + dt
 	mx, my = jin.mouse.position() 
 	mx = mx / 2 
 	my = my / 2
@@ -73,20 +141,16 @@ end
 img:setAnchor(16, 16)
 local cvs = jg.Canvas(320, 240)
 local i = 0
+
 jin.core.onDraw = function() 
 --	if true then return end
-	i = i + 0.1
+	i = i + 0.001
 	jg.bind(cvs)
-	jg.use(effect)
-	effect:send("vec2", "mouse", mx, my)
-	effect:send("number", "i", i)
-	effect:send("Image", "diffuse", diffuse)
-	jg.draw(img, ww / 2, wh / 2, 2, 2)
-	jg.unuse()
-	jg.use(effect)
-	effect:send("Image", "diffuse", diffuse)
-	jg.draw(img, ww / 3, wh / 2, 2, 2)	
-	jg.unuse() 
+		jg.use(lightning)
+			lightning:send("number", "iTime", t)
+			lightning:send("Image", "img", img2)
+			jg.draw(img2, 20, 20)
+		jg.unuse()
 	jg.unbind()	
 	jg.draw(cvs, 0, 0, 2, 2)
 end