Refactor code structure for improved readability and maintainability

samples/auroras.lua

@@ -0,0 +1,156 @@
+-- Auroras by nimitz 2017 (twitter: @stormoid)
+-- License Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
+-- Converted from ShaderToy to live-wallpaper system
+
+effect = nil
+
+function _create()
+    local fxSrc = [[
+in vec2 vPosition;
+
+#define time uTime
+
+mat2 mm2(in float a){float c = cos(a), s = sin(a);return mat2(c,s,-s,c);}
+mat2 m2 = mat2(0.95534, 0.29552, -0.29552, 0.95534);
+float tri(in float x){return clamp(abs(fract(x)-.5),0.01,0.49);}
+vec2 tri2(in vec2 p){return vec2(tri(p.x)+tri(p.y),tri(p.y+tri(p.x)));}
+
+float triNoise2d(in vec2 p, float spd)
+{
+    float z=1.8;
+    float z2=2.5;
+    float rz = 0.;
+    p *= mm2(p.x*0.06);
+    vec2 bp = p;
+    for (float i=0.; i<5.; i++ )
+    {
+        vec2 dg = tri2(bp*1.85)*.75;
+        dg *= mm2(time*spd);
+        p -= dg/z2;
+
+        bp *= 1.3;
+        z2 *= .45;
+        z *= .42;
+        p *= 1.21 + (rz-1.0)*.02;
+
+        rz += tri(p.x+tri(p.y))*z;
+        p*= -m2;
+    }
+    return clamp(1./pow(rz*29., 1.3),0.,.55);
+}
+
+float hash21(in vec2 n){ return fract(sin(dot(n, vec2(12.9898, 4.1414))) * 43758.5453); }
+
+vec4 aurora(vec3 ro, vec3 rd)
+{
+    vec4 col = vec4(0);
+    vec4 avgCol = vec4(0);
+
+    for(float i=0.;i<50.;i++)
+    {
+        float of = 0.006*hash21(gl_FragCoord.xy)*smoothstep(0.,15., i);
+        float pt = ((.8+pow(i,1.4)*.002)-ro.y)/(rd.y*2.+0.4);
+        pt -= of;
+        vec3 bpos = ro + pt*rd;
+        vec2 p = bpos.zx;
+        float rzt = triNoise2d(p, 0.06);
+        vec4 col2 = vec4(0,0,0, rzt);
+        col2.rgb = (sin(1.-vec3(2.15,-.5, 1.2)+i*0.043)*0.5+0.5)*rzt;
+        avgCol =  mix(avgCol, col2, .5);
+        col += avgCol*exp2(-i*0.065 - 2.5)*smoothstep(0.,5., i);
+    }
+
+    col *= (clamp(rd.y*15.+.4,0.,1.));
+
+    return col*1.8;
+}
+
+//-------------------Background and Stars--------------------
+
+vec3 nmzHash33(vec3 q)
+{
+    uvec3 p = uvec3(ivec3(q));
+    p = p*uvec3(374761393U, 1103515245U, 668265263U) + p.zxy + p.yzx;
+    p = p.yzx*(p.zxy^(p >> 3U));
+    return vec3(p^(p >> 16U))*(1.0/vec3(0xffffffffU));
+}
+
+vec3 stars(in vec3 p)
+{
+    vec3 c = vec3(0.);
+    float res = uDesktopSize.x*1.;
+
+    for (float i=0.;i<4.;i++)
+    {
+        vec3 q = fract(p*(.15*res))-0.5;
+        vec3 id = floor(p*(.15*res));
+        vec2 rn = nmzHash33(id).xy;
+        float c2 = 1.-smoothstep(0.,.6,length(q));
+        c2 *= step(rn.x,.0005+i*i*0.001);
+        c += c2*(mix(vec3(1.0,0.49,0.1),vec3(0.75,0.9,1.),rn.y)*0.1+0.9);
+        p *= 1.3;
+    }
+    return c*c*.8;
+}
+
+vec3 bg(in vec3 rd)
+{
+    float sd = dot(normalize(vec3(-0.5, -0.6, 0.9)), rd)*0.5+0.5;
+    sd = pow(sd, 5.);
+    vec3 col = mix(vec3(0.05,0.1,0.2), vec3(0.1,0.05,0.2), sd);
+    return col*.63;
+}
+//-----------------------------------------------------------
+
+void main()
+{
+    vec2 fragCoord = (vPosition * 0.5 + 0.5) * uDesktopSize;
+
+    vec2 q = fragCoord.xy / uDesktopSize.xy;
+    vec2 p = q - 0.5;
+    p.x *= uDesktopSize.x / uDesktopSize.y;
+
+    vec3 ro = vec3(0,0,-6.7);
+    vec3 rd = normalize(vec3(p,1.3));
+    vec2 mo = uMouse.xy / uDesktopSize.xy-.5;
+    mo = (mo==vec2(-.5))?mo=vec2(-0.1,0.1):mo;
+    mo.x *= uDesktopSize.x / uDesktopSize.y;
+    rd.yz *= mm2(mo.y);
+    rd.xz *= mm2(mo.x + sin(time*0.05)*0.2);
+
+    vec3 col = vec3(0.);
+    vec3 brd = rd;
+    float fade = smoothstep(0.,0.01,abs(brd.y))*0.1+0.9;
+
+    col = bg(rd)*fade;
+
+    if (rd.y > 0.){
+        vec4 aur = smoothstep(0.,1.5,aurora(ro,rd))*fade;
+        col += stars(rd);
+        col = col*(1.-aur.a) + aur.rgb;
+    }
+    else //Reflections
+    {
+        rd.y = abs(rd.y);
+        col = bg(rd)*fade*0.6;
+        vec4 aur = smoothstep(0.0,2.5,aurora(ro,rd));
+        col += stars(rd)*0.1;
+        col = col*(1.-aur.a) + aur.rgb;
+        vec3 pos = ro + ((0.5-ro.y)/rd.y)*rd;
+        float nz2 = triNoise2d(pos.xz*vec2(.5,.7), 0.);
+        col += mix(vec3(0.2,0.25,0.5)*0.08,vec3(0.3,0.3,0.5)*0.7, nz2*0.4);
+    }
+
+    FragColor = vec4(col, 1.);
+}
+    ]]
+    effect = Effect.new(fxSrc)
+end
+
+function _update(dt)
+end
+
+function _render()
+    gl.Clear(0, 0, 0, 1.0)
+    effect:Render()
+end