diff --git a/.gitignore b/.gitignore
index e43b0f9..96f05f1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
 .DS_Store
+old/
+new/
diff --git a/22.jpg b/22.jpg
new file mode 100644
index 0000000..3e0b520
Binary files /dev/null and b/22.jpg differ
diff --git a/3.jpg b/3.jpg
new file mode 100644
index 0000000..0b0545c
Binary files /dev/null and b/3.jpg differ
diff --git a/4.jpg b/4.jpg
new file mode 100644
index 0000000..9bb2c0b
Binary files /dev/null and b/4.jpg differ
diff --git a/README.md b/README.md
index d316435..0262c7f 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,2 @@
-# graphics_hw1
-[link](https://billsun.dev/graphics/hw1)
+# graphics_hw2
+[link](https://billsun.dev/graphics/hw2)
diff --git a/RTXoff.svg b/RTXoff.svg
new file mode 100644
index 0000000..80488f7
--- /dev/null
+++ b/RTXoff.svg
@@ -0,0 +1,103 @@
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diff --git a/RTXon.svg b/RTXon.svg
new file mode 100644
index 0000000..d3124d7
--- /dev/null
+++ b/RTXon.svg
@@ -0,0 +1,105 @@
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+<style type="text/css">
+	.st0{fill:#75B943;}
+	.st1{fill:#1D1E1D;}
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+		l-20.35-31.93l-20.55,31.93"/>
+	<path class="st2" d="M221.13,167.89v-1.14h0.73c0.4,0,0.95,0.03,0.95,0.52c0,0.53-0.28,0.62-0.75,0.62H221.13 M221.13,168.7h0.49
+		l1.14,2h1.25l-1.26-2.09c0.65-0.05,1.19-0.36,1.19-1.23c0-1.09-0.75-1.45-2.03-1.45h-1.84v4.77h1.06V168.7 M226.49,168.33
+		c0-2.8-2.17-4.42-4.59-4.42c-2.44,0-4.61,1.62-4.61,4.42c0,2.8,2.18,4.43,4.61,4.43C224.32,172.75,226.49,171.12,226.49,168.33
+		 M225.16,168.33c0,2.04-1.5,3.41-3.27,3.41v-0.01c-1.82,0.01-3.29-1.36-3.29-3.39c0-2.04,1.47-3.4,3.29-3.4
+		C223.67,164.93,225.16,166.29,225.16,168.33"/>
+	<path class="st2" d="M110.83,137.83l0,33.49h9.46v-33.49H110.83z M36.43,137.78v33.54h9.54v-25.46l7.39,0
+		c2.45,0,4.2,0.61,5.37,1.87c1.5,1.59,2.11,4.17,2.11,8.87v14.73h9.25v-18.53c0-13.22-8.43-15.01-16.68-15.01H36.43z M126.06,137.83
+		v33.49h15.34c8.17,0,10.84-1.36,13.73-4.41c2.04-2.14,3.36-6.84,3.36-11.97c0-4.71-1.11-8.91-3.06-11.52
+		c-3.5-4.68-8.55-5.59-16.09-5.59H126.06z M135.44,145.12h4.06c5.9,0,9.71,2.65,9.71,9.52c0,6.88-3.81,9.53-9.71,9.53h-4.06V145.12z
+		 M97.2,137.83l-7.89,26.54l-7.56-26.54l-10.21,0l10.8,33.49h13.63l10.89-33.49H97.2z M162.88,171.32h9.46v-33.48l-9.46,0V171.32z
+		 M189.4,137.84l-13.21,33.46h9.33l2.09-5.91h15.63l1.97,5.91h10.12l-13.3-33.47L189.4,137.84z M195.54,143.95l5.73,15.68h-11.64"/>
+	<path class="st2" d="M61.86,71.16c0,0,12.17-17.96,36.47-19.81v-6.52c-26.91,2.16-50.22,24.96-50.22,24.96s13.2,38.16,50.22,41.65
+		v-6.93C71.16,101.09,61.86,71.16,61.86,71.16"/>
+	<path class="st2" d="M98.33,90.74v6.34c-20.53-3.66-26.23-25-26.23-25s9.86-10.92,26.23-12.69v6.96c-0.01,0-0.02,0-0.03,0
+		c-8.59-1.03-15.3,7-15.3,7S86.75,86.86,98.33,90.74"/>
+	<path class="st2" d="M98.33,32.81v12.02c0.79-0.06,1.58-0.11,2.38-0.14c30.6-1.03,50.54,25.1,50.54,25.1s-22.9,27.84-46.75,27.84
+		c-2.19,0-4.23-0.21-6.16-0.54v7.43c1.64,0.21,3.35,0.33,5.13,0.33c22.2,0,38.25-11.34,53.8-24.75c2.58,2.07,13.13,7.09,15.3,9.28
+		c-14.78,12.38-49.23,22.35-68.75,22.35c-1.88,0-3.69-0.11-5.47-0.29v10.44h84.38V32.81"/>
+	<path class="st2" d="M98.33,59.39v-8.05c0.78-0.05,1.57-0.1,2.38-0.12c22-0.69,36.44,18.91,36.44,18.91s-15.59,21.65-32.31,21.65
+		c-2.41,0-4.56-0.38-6.5-1.04V66.35c8.57,1.04,10.29,4.82,15.44,13.4l11.46-9.66c0,0-8.36-10.96-22.46-10.96
+		C101.23,59.12,99.76,59.23,98.33,59.39"/>
+</g>
+<g>
+	<path class="st3" d="M768.65,113.4c0,32.02-19.46,48.99-43.19,48.99c-24.56,0-41.81-19.04-41.81-47.2
+		c0-29.53,18.35-48.85,43.19-48.85C752.22,66.34,768.65,85.8,768.65,113.4z M696.47,114.92c0,19.87,10.76,37.67,29.67,37.67
+		c19.04,0,29.81-17.53,29.81-38.64c0-18.49-9.66-37.81-29.67-37.81C706.41,76.14,696.47,94.49,696.47,114.92z"/>
+	<path class="st3" d="M784.24,160.87V67.86h13.11l29.81,47.06c6.9,10.9,12.28,20.7,16.7,30.22l0.28-0.14
+		c-1.1-12.42-1.38-23.74-1.38-38.23V67.86h11.32v93.01h-12.14l-29.53-47.2c-6.49-10.35-12.7-20.98-17.39-31.05l-0.41,0.14
+		c0.69,11.73,0.97,22.91,0.97,38.36v39.74H784.24z"/>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+</svg>
diff --git a/index.html b/index.html
index 7480594..37b8809 100644
--- a/index.html
+++ b/index.html
@@ -21,7 +21,8 @@
  </style>
 <body bgcolor=white text=black link=black alink=blue vlink=blue>
 <center>
-<canvas id='canvas1' style="width: 600px; height:600px;" width=1200 height=1200></canvas>
+   <!!--- SUPER SAMPLING THE W/H PARAMS FOR CANVAS ARE RENDER SIZE, IN THE CSS IS ACTUAL(DISPLAY) SIZE.--->
+<canvas id='canvas1' style="overflow: auto; width: 600px; height:600px;" width=1200 height=1200></canvas>
 </center>
 </body>
 
@@ -39,7 +40,7 @@
 
 
 <!!-------- FRAGMENT SHADER: THIS IS WHERE YOU WILL DO YOUR WORK -------->
-<!!-------- FRAGMENT SHADER: MOVED TO ./shader.frag LOADED IN lib2.js -------->
+<!!-------- FRAGMENT SHADER: MOVED TO ./shader.frag!! LOADED IN lib2.js -------->
 <!--script src="shader.frag" id='my_fragment_shader' type='x-shader/x-fragment'> </script>
 
 
@@ -56,27 +57,41 @@ Solar RTX
 <p style="font-size:30px; ">In this homework, I implemented Global illumination w/ 
    Realtime Recursive Ray Tracing! 
 <p>
-<i style="font-size:25px;">Here is how it works:</i>
+<i style="font-size:25px;">Usage: </i>
 <ul>
-   <li>First, I added <a href="http://planetpixelemporium.com/download/download.php?earthmap1k.jpg">texture</a> to the sphere. The code to load the texture is from 
-      <a href="https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/Tutorial/Using_textures_in_WebGL">here</a>. Please wait a sec for the texture to download.</li>
-   <li>Then, I mapped the 3D sphere surface to the rectangular 2D texture picture.  </li>
-   <li>I also make it look like it's rotating by adding uTime to the offset of the texture and reset the offset to 0 whenever it exceeds
-       the width of the texture.</li>
-   <li>I used Perlin Noise to generate fake clouds.</li>
-   <li> I modified the lighting so that the light source won't move with the sphere and 
-      the lighting will change when the sphere moves. I also added specular lights to make it shinier.</li>
-   <li> I tried to add some 'soft shadow' to it. I used a mix of methods inspired by Ambient Occlusion and Ray Tracing.<br>
+   <li>Ctrl+Alt/Option+T: Toggle Texture.</li>
+   <li>Ctrl+S: Download fragment shader.</li>
+   <li>Ctrl+Alt/Option+R: Toggle Recursive Ray Tracing.</li>
+   <li>Ctrl+Alt/Option+N: Reset ViewPoint.</li>
+   <li>Ctrl+Alt/Option+P: Toggle Pause/Resume.</li>
+   <li style="color:red;">Please unfocus the Editing area (click somewhere else on the page) to use hotkeys.</li>
+   <li>Double Click on canvas (WITHOUT key modifiers): Toggle Pause/Resume.</li>
+   <li>MOUSE DRAG, SCROLL/WHEEL ZOOM: Changing Viewing point.</li>
+   <li>Use Chromium based browser for better performance.</li>
+</ul>
+<i style="font-size:25px;">How it works:</i>
+<ul>
+   <li>First, I started with what I've already done in <a href="https://billsun.dev/graphics/hw1">homework 1</a>. Which already included complete Phong shading with 
+      Specular light and much more (spherical texture mapping, simple interactions, improved UI/shader editor).
+   </li>
+   <li> I then merged the code from hw2 and added texture to each sphere.</li>
+   <li> I modified the ray tracing algorithm so that when hitting an object, instead of just returning color calculated from 
+      Phong model:<br>
       <ul>
-         <li>The Ambient lights and diffusion lights are reduced with respect to the distance between the background point and the sphere.</li>
-         <li>The specular light of the background wall is eliminated and the diffusion factor is reduced when the ray shooting from the background point 
-       towards the light source or from the background point towards the camera position intersect with the sphere.</li>
+         <li>It recursively bounces and/or refract(NOT IMPLEMENTED YET) itself spawning new rays.</li>
+         <li>The color of this pixel equals to Ambient + Diffuse + ks*color[Reflected] + kt*color[Refracted]. 
+            (<a href="https://www.cs.drexel.edu/~david/Classes/Papers/p343-whitted.pdf">Turner Whitted Model</a>)</li>
+         <li>The tracing will stop when a ray was not hitting any object or was reflected/refracted n_ref times. </li> 
+         <li>The color/intensity of the final lights are computed via specular component from the Phong model.</li>
+         <li>You may increase n_ref for more iterations, but please proceed with caution, because it may halt the computer.  
+         </li>
       </ul>
-   <li>I added basic interactions such as press ctrl + 't' key to hide/show texture, click on the above canvas to pause/unpause animations. 
-      Just a proof of concept.</li>   
-   <li>Finally, I made some small changes like changing R over time and refined the UI a little bit. I used 
-      <a href="https://ace.c9.io">Ace</a> for code highlighting and autocompletion on the edit panel.</li>
-   <li>Comments begin with '//*' are added by me.</li>
+   <li>I added more interactions, you can now change the viewpoint by 
+      holding shift and alt key while dragging on canvas to rotate,
+      or holding shift and alt while scrolling on canvas to change focal length.
+      This is implemented by applying a transformation matrix to the viewpoint and projection surface.
+   </li>   
+   <li>Finally, I used super sampling via doubling the render dimensions of the canvas to reduce aliasing. SEE comments on index.html</li>
    <li>Repo on <a href="https://github.com/sunyinqi0508/graphics_hw1">Github</a>.</li>
    </li>
  </ul>
@@ -111,18 +126,35 @@ let vs = my_vertex_shader.innerHTML;
    client.send();
 document.body.innerHTML = [''
    ,'<font size=7 color=#909090>' + my_title.innerHTML
+   ,'<img id="rtx" style="float:right;" src="./RTXon.svg" type="image/svg+xml"'
+   ,' alt="Turn Ray Tracing On/OFF" title="Turn Ray Tracing On/OFF" height=60px /img>' 
+   ,'<div id="fps" style="font-size:25;float:right;margin-right:18px;"></div>' 
    ,'<TABLE cellspacing=0 cellpadding=0><TR>'
    ,'<td><font color=red size=5><div id=errorMessage></div></font></td>'
    ,'</TR><TR>'
    ,'<table cellspacing=0>'
    ,'<tr>'
    ,'<td valign=top>'
-   ,'<div id="ace" style="width:800px;height:1780px;"></div>'
-   ,'</td><td valign=top>' + document.body.innerHTML  + '<div style=\'font-size:25px\'>' + my_instructions.innerHTML + '</div>' + '</td>'
+   ,'<div id="ace" style="width:800px;height:2200px;"></div>'
+   ,'</td><td valign=top>' + document.body.innerHTML
+   ,'<input type="number" id="ins" style="margin-left:3px;font-size:24px;width:100px;height:45px" value="4">'
+   ,'<button id="bns" style="margin-left:5px;font-size:24px;width:150px;height:45px">Set Spheres</button>'
+   ,'<div style=\'font-size:25px\'>' + my_instructions.innerHTML + '</div>' + '</td>'
    ,'</tr></table>'
    ,'</TR></TABLE>'
    ].join('');
-
+bns.onclick=function(e){
+   if(ins.value>0 &&ins.value<=ns &&cns!=ins.value)
+   {   
+      cns = ins.value;
+      fragmentShaderDefs = '\n const int cns = ' + cns + ';';
+      if(typeof canvas1.setShaders === "function")
+         {
+            canvas1.setShaders(vs, editor.getSession().getValue());
+            setUniform('1i', 'flags', flags);
+         }
+   }
+}
 // SET UP THE EDITABLE TEXT AREA ON THE LEFT SIDE.
 ace.require("ace/ext/language_tools");
 var editor = ace.edit("ace", {
@@ -144,52 +176,175 @@ editor.setAutoScrollEditorIntoView(true);
 delete editor.KeyBinding;
 let lastTime = Date.now();
 let animating = true;
-let ctrl = false;
-canvas1.addEventListener('click',function(ev){
+let ctrl = false, alt = false, shift = false, fpson = true, moving = false, over = false;
+let mousedx = 0, mousedy = 0, mousedz = 0;
+let cx = 1, cy = 1, sx = 0, sy = 0;
+let mouselastX, mouselastY;
+let lastClick = undefined;
+let pause_resume = function(){
    if(animating)
-      lastTime = Date.now();
-   else
-      startTime += Date.now() - lastTime;   
-   animating = !animating;
+         lastTime = Date.now();
+      else
+         startTime += Date.now() - lastTime;   
+      animating = !animating;
+};
+canvas1.addEventListener('click',function(ev){
+   if(!(shift && alt) && lastClick&& Date.now()-lastClick<400)
+      pause_resume();
+   lastClick = Date.now();
+   //moving = false;
+});
+canvas1.addEventListener('mouseover', function(e){
+   over = true;
+   const mask = 0x8;
+   flags |= mask;
+   setUniform('1i', 'flags', flags);
+});
+canvas1.addEventListener('mousedown', function(e){
+      moving = true
+      mouselastX = mouselastY =  undefined;
+});
+canvas1.addEventListener('mousemove', function(e){
+      if(!(mouselastX==undefined || mouselastY == undefined)&&moving){
+         mousedx -= (mouselastX - e.offsetX)/60;
+         mousedy -= (mouselastY - e.offsetY)/60;
+         cx = Math.cos(mousedx);
+         sx = Math.sin(mousedx);
+         cy = Math.cos(mousedy);
+         sy = Math.sin(mousedy);
+         setUniform('4f', 'rot', cx, sx, cy, sy);
+         const mask = 0x4;
+         flags |= mask;
+         setUniform('1i', 'flags', flags);
+      }
+      // if(over){
+      //    let x=e.offsetX/300-1;
+      //    let y=e.offsetY/300-1;
+      //    let z=-1-3-mousedz;
+      //    let tx = cx*x+sy*sx*y+sx*cy*z;
+      //    let ty = cy*y-sy*z;
+      //    let tz = -sx*x+cx*sy*y+cx*cy*z;
+      //    let len = Math.sqrt(tx*tx + ty*ty+tz*tz);
+      //    setUniform('3f', 'fDir', tx/len, ty/len, tz/len);
+      // }
+      mouselastX = e.offsetX;
+      mouselastY = e.offsetY;
+});
+canvas1.addEventListener('mouseup', function(e){
+   // if(ctrl && alt && moving){
+   // }
+   moving = false;
+});
+canvas1.addEventListener('mouseout', function(e){
+   // if(ctrl && alt && moving){
+   // }
+   const mask = 0x8;
+   flags &= !mask;
+   setUniform('1i', 'flags', flags);
+   over = false;
+   moving = false;
 });
+canvas1.addEventListener('wheel', function(e){
+      mousedz += e.wheelDelta/600;
+      setUniform('1f', 'dFL', mousedz);
+      e.stopImmediatePropagation();
+});
+canvas1.scroll(function(e) {e.stopPropagation();});
+rtx.style.cursor="pointer";
+let rtswitch = function(){
+   const mask = 0x2;
+   let rtstatus = !(flags&mask);
+   if (rtstatus)
+      rtx.src='./RTXoff.svg';
+   else
+      rtx.src='./RTXon.svg';
+   flags = (flags&(!mask)) | (rtstatus?mask:0);
+   setUniform('1i', 'flags', flags);
+}
+rtx.addEventListener('click', rtswitch);
+var requestAnimationFrame = window.requestAnimationFrame ||
+ window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
+let fpscounter = function(time){
+      if (start === undefined)
+         start = time;
+      else
+         fps.innerHTML = Math.round(10000/(time-start))/10 + ' fps';
+      start = time;
+      if(fpson)
+         requestAnimationFrame(fpscounter);
+      else{
+         start = undefined;
+         fps.innerHTML = '';
+      }
+   };
 document.addEventListener('keydown',(e)=>{
+   if(e.code.startsWith('Shift'))
+      shift = true;
    if(e.code.startsWith('Control'))
-   {
       ctrl = true;
-   }
-   else if(ctrl && e.code == 'KeyT')
-   {
-      mask = 0x1;
+   if(e.code.startsWith('Alt'))
+      alt = true;
+   else if(ctrl && alt && e.code == 'KeyT'){
+      const mask = 0x1;
       flags = flags&!mask | (!(flags&mask)?mask:0);
       setUniform('1i', 'flags', flags);
    }
-   else if (ctrl && e.code == 'KeyS')
-   {
+   else if (ctrl &&e.code == 'KeyS'){
       let a = document.createElement('a');
       a.href = "data:text/plain,"+encodeURIComponent(editor.getSession().getValue());
       a.download = 'shader.frag';
       a.click();
    }
+   else if(ctrl && alt&&e.code == 'KeyR')
+      rtswitch();
+   else if(ctrl && alt&&e.code == 'KeyN')
+   {
+      flags = 0;
+      moving = false;
+      mousedx = mousedy = mousedz = 0;
+      cx = Math.cos(mousedx);
+      sx = Math.sin(mousedx);
+      cy = Math.cos(mousedy);
+      sy = Math.sin(mousedy);
+      rtx.src='./RTXon.svg';
+      setUniform('4f', 'rot', cx, sx, cy, sy);
+      setUniform('1f', 'dFL', mousedz);
+      setUniform('1i', 'flags', flags);
+   }
+   else if(ctrl && alt&&e.code == 'KeyP')
+      pause_resume();
+   else if(ctrl && alt&&e.code == 'KeyF')
+      if(!fpson)
+      {
+         fpson = true;
+         requestAnimationFrame(fpscounter);
+      }
+      else
+         fpson = false;
+   // else if(e.code =='KeyV')
+   //    alert(' '+ mousedx+ ' ' + mousedy + ' '+mousedz)
+
 });
 
 document.addEventListener('keyup',(e)=>{
    if(e.code.startsWith('Control'))
-   {
       ctrl = false;
-   }
+   if(e.code.startsWith('Alt'))
+      alt = false;
+   if(e.code.startsWith('Shift'))
+      shift = false;
 });
 // SET THE CURRENT TIME IN SECONDS BEFORE RENDERING EACH FRAME.
 
 let startTime = Date.now();
-
+let lastFrameTime = 0;
 function animate(gl) {
    if(animating)
       setUniform('1f', 'uTime', (Date.now() - startTime) / 1000);
    else
       setUniform('1f', 'uTime', (lastTime - startTime) / 1000);
-
 }
-
-
+let start;
+requestAnimationFrame(fpscounter);
 </script>
 
diff --git a/lib2.js b/lib2.js
index 3247002..2dde401 100644
--- a/lib2.js
+++ b/lib2.js
@@ -15,8 +15,10 @@ let fragmentShaderHeader = [''                      // WHATEVER CODE WE WANT TO
    , '  r+=sin(6.3*dot(P,fract(D)-.5))*pow(max(0.,1.-2.*dot(P,P)),4.);'
    , '} return .5 * sin(r); }'
 ].join('\n');
-
-let nfsh = fragmentShaderHeader.split('\n').length; // NUMBER OF LINES OF CODE IN fragmentShaderHeader
+let ns = 4, cns = 4;
+fragmentShaderHeader+= 'const int ns = ' + ns + ';\n';
+let fragmentShaderDefs = 'const int cns = ' + cns + ';\n';
+let nfsh = fragmentShaderHeader.split('\n').length + 1; // NUMBER OF LINES OF CODE IN fragmentShaderHeader
 
 let isFirefox = navigator.userAgent.indexOf('Firefox') > 0;         // IS THIS THE FIREFOX BROWSER?
 let errorMsg = '';
@@ -90,7 +92,7 @@ function gl_start(canvas, vertexShader, fragmentShader) {           // START WEB
 
    setTimeout(function () {
       try {
-         canvas.gl = canvas.getContext('webgl2');              // Make sure WebGl is supported. IT WOULD BE GREAT TO USE WEBGL2 INSTEAD.
+         canvas.gl = canvas.getContext('experimental-webgl');              // Make sure WebGl is supported. IT WOULD BE GREAT TO USE WEBGL2 INSTEAD.
       } catch (e) { throw 'Sorry, your browser does not support WebGL.'; }
 
       canvas.setShaders = function (vertexShader, fragmentShader) {         // Add the vertex and fragment shaders:
@@ -138,20 +140,19 @@ function gl_start(canvas, vertexShader, fragmentShader) {           // START WEB
          };
 
          addshader(gl.VERTEX_SHADER, vertexShader);                         // Add the vertex and fragment shaders.
-         addshader(gl.FRAGMENT_SHADER, fragmentShaderHeader + fragmentShader);
+         addshader(gl.FRAGMENT_SHADER, fragmentShaderHeader +fragmentShaderDefs+ fragmentShader);
 
          gl.linkProgram(program);                                               // Link the program, report any errors.
          if (!gl.getProgramParameter(program, gl.LINK_STATUS))
             console.log('Could not link the shader program!');
          gl.useProgram(program);
          gl.program = program;
-         const ns = 2;
          for(let i = 0; i < ns; ++i){
             loadTexture(gl, './'+(i+1)+'.jpg', i); //Texture loading.
             textures[i] = i;
          }
          gl.uniform1iv(gl.getUniformLocation(program, 'uSampler'), textures);
-
+         setUniform('4f', 'rot', Math.cos(mousedx), Math.sin(mousedx), Math.cos(mousedy), Math.sin(mousedz));
          gl.bindBuffer(gl.ARRAY_BUFFER, gl.createBuffer());                     // Create a square as a triangle strip
          gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(                       //    consisting of two triangles.
             [-1, 1, 0, 1, 1, 0, -1, -1, 0, 1, -1, 0]), gl.STATIC_DRAW);
diff --git a/shader.frag b/shader.frag
index ee12c36..8f853c6 100644
--- a/shader.frag
+++ b/shader.frag
@@ -1,26 +1,43 @@
 
-vec3 foregroundColor = vec3(.0841, .5329, .9604);
+vec3 foregroundColor = vec3(.0841, .5329, .9604); 
 vec3 groundColor = vec3(.2, .3, .5);
 vec4 groundSpecular = vec4(.71, .71, .71, 10.);
 uniform float uTime;// TIME, IN SECONDS
 uniform int flags;
-//FLAGS 0-RT, 1-TEX, 2-
+//FLAGS 0-TEX, 1-RT, 2-MOVED, 3-FLASH, 4-TEX_ROT, 5-CLOUD
+
+uniform vec4 rot; //ROTATION VALUES USED TO CALCULATE TRANSFORMATION MATRIX
+//rot=[cosx, sinx, cosy, siny], x, y BING ROTATED ANGLE
+uniform float dFL; //DELTA on FOCAL LENGTH
+uniform vec3 fDir;//Flash light direction
 varying vec3 vPos;// -1 < vPos.x < +1
 // -1 < vPos.y < +1
 //      vPos.z == 0
 
-float fl=3.;
+float fl=3.;//ORIGINAL FOCAL LENGTH
 const float pi=3.14159265359;
-const int n_ref=2;
-const int ns=2;
+const float _2pi=2.*pi;
+const int n_ref=5; //<<=======***********************MAX NUMBER OF RAY TRACING RECURRSIONS. INCREASE IT IF YOUR GRAPHICS CARD CAN HANDLE.**************************** 
+//const int ns=4; ns is added from .js
 vec4 Sph[ns];
 uniform sampler2D uSampler[ns];
 vec3 Ambient[ns];
 vec3 Diffuse[ns];
 vec4 Specular[ns];
-struct RT{
+float ks[ns];
+struct Sphere{ //UPDATED SPHERE STRUCTURE THAT SUPPORTS TRANSPARENCY.(UNUSED)
+   vec4 Pos;
+   vec3 Ambient;
+   vec3 Diffuse;
+   vec4 Specular;
+   int textureid;
+   float ks, kt;
+};
+struct RT{ //STACK FOR RECURSIVE RAY TRACING.
    vec3 color;
    float ks;
+   // vec3 colorr;
+   // float kt;
    // vec3 ptr;
    // vec3 normal;
 } stack[n_ref];
@@ -33,24 +50,31 @@ float clampv(float val,float l,float h){
    return val<l?l:val>h?h:val;
 }
 void main(){
-   
    ////////////////////////////////////////////////
    //
    // HERE, FOR YOUR HOMEWORK, YOU CAN WRITE ANY
    // CODE YOU LIKDEFINE A COLOR FOR THIS FRAGMENT.
    
    // LIGHT DIRECTION AND COLOR
-   
+   //* I USED LDir AS LIGHT POSITION
+   //* I NORMALIZED IT AFTER GETTING THE 
+   //* DIRECTION BY SUBTRACTING IT FROM THE POINT
    vec3 LDir=vec3(.5,.5,.5);
    vec3 LCol=vec3(1.,1.,1.);
    
    // SPHERE
+   Sph[3]=vec4(.9*sin(uTime*.4),0.,.9*cos(uTime*.4),.25);
+   Sph[2]=vec4(.22*sin(uTime*1.2),0.05,.22*cos(uTime*1.2),.02);
+   Sph[0]=vec4(.45*sin(uTime),0.05*cos(uTime + 1.),.45*cos(uTime),.1);
+   Sph[1]=vec4(0.,0.,0.,.15);
    
-   Sph[0]=vec4(.5*sin(uTime),0.,.5*cos(uTime),.2);
-   Sph[1]=vec4(0.,0.,0.,.2);
-   
-   // SURFACE REFLECTANCE PROPERTIES
-   
+   // SURFACE REFLECTANCE PROPERTIES, can be transferred from .js
+   Ambient[3]=vec3(.1,.1,.1);// r,g,b
+   Diffuse[3]=vec3(.71,.71,.71);// r,g,b
+   Specular[3]=vec4(.71,.71,.71,10.);// r,g,b,power
+   Ambient[2]=vec3(.1,.05,.05);// r,g,b
+   Diffuse[2]=vec3(.71,.71,.71);// r,g,b
+   Specular[2]=vec4(.71,.71,.71,10.);// r,g,b,power
    Ambient[1]=vec3(.1,.05,.05);// r,g,b
    Diffuse[1]=vec3(1.,.5,.5);// r,g,b
    Specular[1]=vec4(1.,.5,.5,10.);// r,g,b,power
@@ -58,25 +82,37 @@ void main(){
    Ambient[0]=vec3(.05,.05,.1);// r,g,b
    Diffuse[0]=vec3(.5,.5,1.);// r,g,b
    Specular[0]=vec4(1.,.5,.5,20.);// r,g,b,power
-   
+   ks[0] = 0.25;
+   ks[1] = 0.1;
+   ks[2] = 0.3;
+   ks[3] = 0.05;
    // INITIALIZE TO A BACKGROUND COLOR
-   
    vec3 color=vec3(.2, .3, .5);
-   
+   float ca=rot.x, sa = rot.y, cb=rot.z, sb=rot.w;
+   mat3 transformation, invTr;//Transformation matrix for viewpoint.
+   transformation[0] = vec3(ca, sb*sa, sa*cb);//because the matrices are all the same,
+   transformation[1] = vec3(0, cb, -sb);//We don't need to calculate it for every pixel
+   transformation[2] = vec3(-sa,ca*sb,ca*cb);//So, we get it from the CPU
+   invTr[0] = vec3(ca, 0, -sa);//it's inverse, to calculate texture mapping.
+   invTr[1] = vec3(sa*sb, cb, ca*sb);
+   invTr[2] = vec3(cb*sa, -sb, ca*cb);
+   vec3 trPos = transformation*((dFL+fl+1.)/(fl+1.))*vec3(vPos.xy, -1);
    // COMPUTE THE RAY ORIGIN AND DIRECTION
-   float x=vPos.x;
-   float y=vPos.y;
-   
-   vec3 V=vec3(0.,0.,fl);
-   vec3 W=normalize(vec3(x,y,-fl));
+   vec3 V0=transformation*vec3(0.,0.,fl+dFL), V = V0;
+   vec3 W=normalize(trPos-V);
    // RAY TRACE TO ALL OBJECTS IN THE SCENE
-   bool rtxoff = getflag(flags, 1);
+   bool rtxoff = getflag(flags, 1), 
+   showtexture = !getflag(flags,0), 
+   moved = getflag(flags,2)//,
+//   flash = true;//getflag(flags, 3)
+   ;//get flags.
+ //  bool hit = false;
    int cnt_ref = n_ref;
    for(int j=0;j<n_ref;j++)
    {
       float tMin=10000.;
       int iMin = -1;
-      for(int i=0;i<ns;i++){
+      for(int i=0;i<cns;i++){
          // SHIFT COORDINATES, SO THAT SPHERE IS AT (0,0,0)
          vec3 Vp=V-Sph[i].xyz;
          // SOLVE FOR QUADRATIC EQUATION IN t
@@ -86,8 +122,8 @@ void main(){
          if(D>0.){
             float t=-B-sqrt(D);
             if(t > 0. && t < tMin){
-               tMin = t;
-               iMin = i;
+               tMin = t; //This is an optimization, we don't have to do lighting/tex
+               iMin = i; // for objects that are occuluded, which is expensive!
             }
          }
       }
@@ -95,47 +131,61 @@ void main(){
       if(iMin >= 0){
          float t = tMin;
          vec3 S=V+t*W;
-         for(int i = 0; i < ns; ++ i)
-            if(i == iMin)
-            {
-               //*TEXTURE MAPPING
-               vec3 tex_sph=S-Sph[i].xyz;
+         for(int i = 0; i < cns; ++ i)
+            if(i == iMin) //* Because GLSL doesn't support non-const index, 
+            {             //*  we have to get Sph[iMin], uSampler[iMin], etc. this way
+               //*Good old TEXTURE MAPPING from hw1
+               vec3 tex_sph = (S-Sph[i].xyz);
+               if(moved)
+                  tex_sph=invTr*tex_sph;//* transform the sphere to original place if view point moved;
+                                        //* This is super expensive! plus it's in the inner loop!!
+                                        //* We added a flag to disable it when the viewport is not moved!
                float R=Sph[i].w;
                float tex_x=acos(abs(tex_sph.x)/sqrt(R*R-tex_sph.y*tex_sph.y));
                if(tex_sph.x>0.)
                   tex_x=pi-tex_x;
-               tex_x=R*tex_x;
                tex_x*=1.5708;//*Correct aspect ratio of texture 2:1 -> 2pir:2r
-               tex_x=tex_x+float(uTime)*R;
-               float _2pir=2.*pi*R;
-               float quo=float(int(tex_x/_2pir));
-               tex_x=clampv((tex_x-quo*_2pir),0.,_2pir)/_2pir;
+               tex_x=tex_x+float(uTime);
+               float quo=float(int(tex_x/_2pi));
+               tex_x=tex_x/_2pi -quo;
                vec3 texture_color;
-               if(!getflag(flags,0))
+               if(showtexture)
                   texture_color=texture2D(uSampler[i],vec2(tex_x,((R-tex_sph.y)/(2.*R)))).xyz;
                else texture_color = foregroundColor;
                vec3 N=normalize(S-Sph[i].xyz);
                //*DIRECTIONS ARE NORMALIZED TO GET THE CORRECT PHONG LIGHTING
-               vec3 realLDir=normalize(LDir-S);
+               vec3 realLDir=normalize(LDir-S); 
                color=(
                      Ambient[i]
                      +Diffuse[i]*max(0.,dot(N,realLDir))*LCol
                   )*texture_color
                ;
                // + SPECULAR COMPONENT GOES HERE
-               if(rtxoff || j == n_ref - 1)
-                  color += float(j) * Specular[i].xyz*pow(max(0.,dot(2.*dot(N,realLDir)*N-realLDir,-W)),Specular[i].w);
-               stack[j] = RT(color, 0.15);
-               V = S;
-               W = -normalize(2. * dot(N, W) * N - W);
-               break;
+               if(rtxoff || j == n_ref - 1) //if it's the last ray
+                  color += sqrt(float(j+1)) * Specular[i].xyz*pow(max(0.,
+                  dot(2.*dot(N,realLDir)*N-realLDir,-W)),Specular[i].w);
+               //*Pushing current color and ks into stack.
+               //*suppose ks is 0.15 for all spheres, we can 
+               //*of course support different ks, kt for different object
+               //*but I didn't have time to do that, just a proof of concept,
+               //*I defined the new sphere structure that could be used in the future.
+               stack[j] = RT(color, ks[i]);
+               V = S; //*NEXT RAY SHOOTING FROM THE INTERSECTION POINT 
+               // if(flash && j == 0){
+               //    V0 = V - V0;
+               //    hit = true;
+               // }               
+               W = -normalize(2. * dot(N, W) * N - W);//*W is the next direction of the next ray.
+
+               break;// this is only the innerloop, RT is still going!
             }
       }
       else {
       // TO SIMIPIFY THINGS UP, I'LL ASSUME THAT EVERYTHING 
       // IS INSIDE THE BOUNDING BOX [(-1,-1,-1), (1,1,1)]
-      // AND THERE'S A INFINITE FLOOR [y = -1]
-
+      // AND THERE'S A FLOOR at [y = -1] THE NORMAL IS (0,1,0)
+      // Because We assumed that the light always hit sphere first,
+      // It will have wirld behavior when you rotate the scene upsidedown.
          float t = -(.2+V.y)/W.y;
          float sx = V.x + t* W.x, sz = V.z + t * W.z;
 
@@ -144,28 +194,32 @@ void main(){
             vec3 S = vec3(sx, -.2, sz);
             vec3 realLDir=normalize(LDir - S);
             color=(
-                  0.5
-                  +0.5*max(0.,realLDir.y)*LCol
+                  0.5 //ambient for ground
+                  +0.5*max(0.,realLDir.y)*LCol //diffusion for ground
                )*groundColor
             ;
             // + SPECULAR COMPONENT GOES HERE
             if(rtxoff || j == n_ref - 1)
-               color += float(j)*groundSpecular.xyz*
+               color += sqrt(float(j+1))*groundSpecular.xyz* //specular for ground.
                   pow(max(0., dot(vec3(-realLDir.x, realLDir.y,-realLDir.z),-W)),groundSpecular.w);
-            stack[j] = RT(color, 0.1);
-            V = S;
-            W = vec3(W.x, -W.y, W.z);
+            stack[j] = RT(color, 0.15); //ks of ground is 0.1
+            V = S; //Same as above, trace again from S, dir = reflect(W, N).
+            // if(flash && j == 0){
+            //    V0 = W;
+            //    hit = true;
+            // }
+            W = vec3(W.x, -W.y, W.z); 
          }
          else{
             if(j > 0)
             {
-               stack[j] = RT(vec3(12.,12.,12.)*pow(max(0.,dot(W, normalize(LDir - V))), 10.), 0.);
+               // If the light bounces away! The color of it is calculated by 
+               stack[j] = RT(sqrt(float(j+1))*vec3(4.,4.,4)*pow(max(0.,dot(W, normalize(LDir - V))), 10.), 0.);
                cnt_ref = j + 1;
             }
-            else
-               cnt_ref = j;
-
-            break;
+            else //If the light hits the void in the first place, it's just black!
+               cnt_ref = j;//j is always 0 in this case.
+            break; //The light is shooting into the void, let's stop RT.
          }
       }       
       // RTX off
@@ -180,9 +234,9 @@ void main(){
       float currks = 1.;
       for(int i = 0; i < n_ref; ++i)
       {
-         if(i >= cnt_ref)
+         if(i >= cnt_ref)//same trick to use bounded non-const on indexes
          {
-            color += currks * stack[i - 1].color;
+            color += currks * stack[i - 1].color; //if there're less than n_ref rays, e.g. ray go to the void.
             break;
          }
          color += currks *(1.-stack[i].ks) * stack[i].color;
@@ -192,6 +246,7 @@ void main(){
          color += currks * stack[n_ref - 1].color;
    }
    // APPLY GAMMA CORRECTION AND SET THE PIXEL COLOR.
+
    gl_FragColor=vec4(sqrt(color),1.);
 }
    
\ No newline at end of file