textures

06/gradient.frag

@@ -11,9 +11,9 @@ uniform float u_time;
 vec3 colorA = vec3(0.149,0.141,0.912);
 vec3 colorB = vec3(1.000,0.833,0.224);
 
-float plot (vec2 _st, float _pct){
-  return  smoothstep( _pct-0.01, _pct, _st.y) - 
-          smoothstep( _pct, _pct+0.01, _st.y);
+float plot (vec2 st, float pct){
+  return  smoothstep( pct-0.01, pct, st.y) - 
+          smoothstep( pct, pct+0.01, st.y);
 }
 
 void main() {

07/cross.frag

@@ -9,20 +9,20 @@ uniform vec2 u_resolution;
 uniform vec2 u_mouse;
 uniform float u_time;
 
-float box(in vec2 _st, in vec2 _size){
-    _size = vec2(0.5) - _size*0.5;
-    vec2 uv = smoothstep(_size,
-                        _size+vec2(0.001),
-                        _st);
-    uv *= smoothstep(_size,
-                    _size+vec2(0.001),
-                    vec2(1.0)-_st);
+float box(in vec2 st, in vec2 size){
+    size = vec2(0.5) - size*0.5;
+    vec2 uv = smoothstep(size,
+                        size+vec2(0.001),
+                        st);
+    uv *= smoothstep(size,
+                    size+vec2(0.001),
+                    vec2(1.0)-st);
     return uv.x*uv.y;
 }
 
-float cross(in vec2 _st, float _size){
-    return  box(_st, vec2(_size,_size/4.)) + 
-            box(_st, vec2(_size/4.,_size));
+float cross(in vec2 st, float size){
+    return  box(st, vec2(size,size/4.)) + 
+            box(st, vec2(size/4.,size));
 }
 
 void main(){

07/triangle-making.frag

@@ -10,21 +10,21 @@ uniform vec2 u_mouse;
 uniform float u_time;
 
 // Based on https://www.shadertoy.com/view/4sSSzG
-float triangleDF(vec2 _st, 
-                vec2 _p0, vec2 _p1, vec2 _p2){
+float triangleDF(vec2 st, 
+                vec2 p0, vec2 p1, vec2 p2){
   vec3 e0, e1, e2;
 
-  e0.xy = normalize(_p1 - _p0).yx * vec2(+1.0, -1.0);
-  e1.xy = normalize(_p2 - _p1).yx * vec2(+1.0, -1.0);
-  e2.xy = normalize(_p0 - _p2).yx * vec2(+1.0, -1.0);
+  e0.xy = normalize(p1 - p0).yx * vec2(+1.0, -1.0);
+  e1.xy = normalize(p2 - p1).yx * vec2(+1.0, -1.0);
+  e2.xy = normalize(p0 - p2).yx * vec2(+1.0, -1.0);
 
-  e0.z = dot(e0.xy, _p0);
-  e1.z = dot(e1.xy, _p1);
-  e2.z = dot(e2.xy, _p2);
+  e0.z = dot(e0.xy, p0);
+  e1.z = dot(e1.xy, p1);
+  e2.z = dot(e2.xy, p2);
 
-  float a = max(0.0, dot(e0.xy, _st) - e0.z);
-  float b = max(0.0, dot(e1.xy, _st) - e1.z);
-  float c = max(0.0, dot(e2.xy, _st) - e2.z);
+  float a = max(0.0, dot(e0.xy, st) - e0.z);
+  float b = max(0.0, dot(e1.xy, st) - e1.z);
+  float c = max(0.0, dot(e2.xy, st) - e2.z);
 
   return length(vec3(a, b, c)*2.0);
 }

07/triangle.frag

@@ -10,24 +10,24 @@ uniform vec2 u_mouse;
 uniform float u_time;
 
 // Based on https://www.shadertoy.com/view/4sSSzG
-float triangle (vec2 _st, 
-                vec2 _p0, vec2 _p1, vec2 _p2, 
-                float _smoothness){
+float triangle (vec2 st, 
+                vec2 p0, vec2 p1, vec2 p2, 
+                float smoothness){
   vec3 e0, e1, e2;
 
-  e0.xy = normalize(_p1 - _p0).yx * vec2(+1.0, -1.0);
-  e1.xy = normalize(_p2 - _p1).yx * vec2(+1.0, -1.0);
-  e2.xy = normalize(_p0 - _p2).yx * vec2(+1.0, -1.0);
+  e0.xy = normalize(p1 - p0).yx * vec2(+1.0, -1.0);
+  e1.xy = normalize(p2 - p1).yx * vec2(+1.0, -1.0);
+  e2.xy = normalize(p0 - p2).yx * vec2(+1.0, -1.0);
 
-  e0.z = dot(e0.xy, _p0) - _smoothness;
-  e1.z = dot(e1.xy, _p1) - _smoothness;
-  e2.z = dot(e2.xy, _p2) - _smoothness;
+  e0.z = dot(e0.xy, p0) - smoothness;
+  e1.z = dot(e1.xy, p1) - smoothness;
+  e2.z = dot(e2.xy, p2) - smoothness;
 
-  float a = max(0.0, dot(e0.xy, _st) - e0.z);
-  float b = max(0.0, dot(e1.xy, _st) - e1.z);
-  float c = max(0.0, dot(e2.xy, _st) - e2.z);
+  float a = max(0.0, dot(e0.xy, st) - e0.z);
+  float b = max(0.0, dot(e1.xy, st) - e1.z);
+  float c = max(0.0, dot(e2.xy, st) - e2.z);
 
-  return smoothstep(_smoothness * 2.0, 
+  return smoothstep(smoothness * 2.0, 
                     1e-7, 
                     length(vec3(a, b, c)));
 }

10/1d-random.frag

@@ -5,6 +5,7 @@ precision mediump float;
 #endif
 
 uniform vec2 u_resolution;
+uniform vec2 u_mouse;
 uniform float u_time;
 
 float plot(vec2 _st, float _pct){

10/2d-random-mosaic.frag

@@ -5,6 +5,7 @@ precision mediump float;
 #endif
 
 uniform vec2 u_resolution;
+uniform vec2 u_mouse;
 uniform float u_time;
 
 float random (in vec2 _st) { 

10/2d-random-truchet.frag

@@ -7,6 +7,7 @@ precision mediump float;
 #define PI 3.14159265358979323846
 
 uniform vec2 u_resolution;
+uniform vec2 u_mouse;
 uniform float u_time;
 
 float random (in vec2 _st) { 

10/2d-random.frag

@@ -5,6 +5,7 @@ precision mediump float;
 #endif
 
 uniform vec2 u_resolution;
+uniform vec2 u_mouse;
 uniform float u_time;
 
 float random (in vec2 _st) { 

11/1d-noise.frag

@@ -6,20 +6,20 @@ uniform vec2 u_resolution;
 uniform vec2 u_mouse;
 uniform float u_time;
 
-float plot(vec2 _st, float _pct){
-  return  smoothstep( _pct-0.01, _pct, _st.y) - 
-          smoothstep( _pct, _pct+0.01, _st.y);
+float plot(vec2 st, float pct){
+  return  smoothstep( pct-0.01, pct, st.y) - 
+          smoothstep( pct, pct+0.01, st.y);
 }
 
-float random (in float _x) {
-    return fract(sin(_x)*1e4);
+float random (in float x) {
+    return fract(sin(x)*1e4);
 }
 
 // Based on Morgan McGuire @morgan3d
 // https://www.shadertoy.com/view/4dS3Wd
-float noise (in float _x) {
-    float i = floor(_x);
-    float f = fract(_x);
+float noise (in float x) {
+    float i = floor(x);
+    float f = fract(x);
     float u = f * f * (3.0 - 2.0 * f);
     return mix(random(i), random(i + 1.0), u);
 }

11/2d-noise.frag

@@ -6,17 +6,17 @@ uniform vec2 u_resolution;
 uniform vec2 u_mouse;
 uniform float u_time;
 
-float random (in vec2 _st) { 
-    return fract(sin(dot(_st.xy,
+float random (in vec2 st) { 
+    return fract(sin(dot(st.xy,
                          vec2(12.9898,78.233)))* 
         43758.5453123);
 }
 
 // Based on Morgan McGuire @morgan3d
 // https://www.shadertoy.com/view/4dS3Wd
-float noise (in vec2 _st) {
-    vec2 i = floor(_st);
-    vec2 f = fract(_st);
+float noise (in vec2 st) {
+    vec2 i = floor(st);
+    vec2 f = fract(st);
 
     // Four corners in 2D of a tile
     float a = random(i);

11/3d-noise.frag

@@ -6,17 +6,17 @@ uniform vec2 u_resolution;
 uniform vec2 u_mouse;
 uniform float u_time;
 
-float random (in float _x) {
-    return fract(sin(_x)*1e4);
+float random (in float x) {
+    return fract(sin(x)*1e4);
 }
 
 // Based on Morgan McGuire @morgan3d
 // https://www.shadertoy.com/view/4dS3Wd
-float noise (in vec3 _p) {
+float noise (in vec3 p) {
     const vec3 step = vec3(110.0, 241.0, 171.0);
 
-    vec3 i = floor(_p);
-    vec3 f = fract(_p);
+    vec3 i = floor(p);
+    vec3 f = fract(p);
  
     // For performance, compute the base input to a 
     // 1D random from the integer part of the 

11/noise-move.frag

@@ -6,6 +6,7 @@ precision mediump float;
 #endif
 
 uniform vec2 u_resolution;
+uniform vec2 u_mouse;
 uniform float u_time;
 
 float random (in float _x) {

11/noise.frag

@@ -5,27 +5,27 @@ precision mediump float;
 uniform vec2 u_resolution;
 uniform float u_time;
 
-float random (in float _x) {
-    return fract(sin(_x)*1e4);
+float random (in float x) {
+    return fract(sin(x)*1e4);
 }
 
-float random (in vec2 _st) { 
-    // return fract(sin(dot(_st.xy ,vec2(12.9898,78.233))) * 43758.5453123);
-    return fract( 1e4 * sin(17.0 * _st.x + _st.y * 0.1) * (0.1 + abs(sin(_st.y * 13.0 + _st.x)))); 
+float random (in vec2 st) { 
+    // return fract(sin(dot(st.xy ,vec2(12.9898,78.233))) * 43758.5453123);
+    return fract( 1e4 * sin(17.0 * st.x + st.y * 0.1) * (0.1 + abs(sin(st.y * 13.0 + st.x)))); 
 }
 
 // Based on Morgan McGuire @morgan3d
 // https://www.shadertoy.com/view/4dS3Wd
-float noise (in float _x) {
-    float i = floor(_x);
-    float f = fract(_x);
+float noise (in float x) {
+    float i = floor(x);
+    float f = fract(x);
     float u = f * f * (3.0 - 2.0 * f);
     return mix(random(i), random(i + 1.0), u);
 }
 
-float noise (in vec2 _st){
-    vec2 i = floor(_st);
-    vec2 f = fract(_st);
+float noise (in vec2 st){
+    vec2 i = floor(st);
+    vec2 f = fract(st);
 
     // Four corners in 2D of a tile
     float a = random(i);
@@ -44,11 +44,11 @@ float noise (in vec2 _st){
     return mix(a, b, u.x) + (c - a) * u.y * (1.0 - u.x) + (d - b) * u.x * u.y;
 }
 
-float noise (in vec3 _p) {
+float noise (in vec3 p) {
     const vec3 step = vec3(110.0, 241.0, 171.0);
 
-    vec3 i = floor(_p);
-    vec3 f = fract(_p);
+    vec3 i = floor(p);
+    vec3 f = fract(p);
  
     // For performance, compute the base input to a 1D random from the integer part of the argument and the 
     // incremental change to the 1D based on the 3D -> 1D wrapping
@@ -63,41 +63,39 @@ float noise (in vec3 _p) {
 
 #define NUM_OCTAVES 5
 
-float fbm ( in float _x) {
+float fbm ( in float x) {
     float v = 0.0;
     float a = 0.5;
     float shift = float(100.0);
     for (int i = 0; i < NUM_OCTAVES; ++i) {
-        v += a * noise(_x);
-        _x = _x * 2.0 + shift;
+        v += a * noise(x);
+        x = x * 2.0 + shift;
         a *= 0.5;
     }
     return v;
 }
 
-
-float fbm ( in vec2 _st) {
+float fbm ( in vec2 st) {
     float v = 0.0;
     float a = 0.5;
     vec2 shift = vec2(100.0);
     // Rotate to reduce axial bias
     mat2 rot = mat2(cos(0.5), sin(0.5), -sin(0.5), cos(0.50));
     for (int i = 0; i < NUM_OCTAVES; ++i) {
-        v += a * noise(_st);
-        _st = rot * _st * 2.0 + shift;
+        v += a * noise(st);
+        st = rot * st * 2.0 + shift;
         a *= 0.5;
     }
     return v;
 }
 
-
-float fbm ( in vec3 _p) {
+float fbm ( in vec3 p) {
     float v = 0.0;
     float a = 0.5;
     vec3 shift = vec3(100);
     for (int i = 0; i < NUM_OCTAVES; ++i) {
-        v += a * noise(_p);
-        _p = _p * 2.0 + shift;
+        v += a * noise(p);
+        p = p * 2.0 + shift;
         a *= 0.5;
     }
     return v;

11/wood.frag

@@ -9,17 +9,17 @@ uniform vec2 u_resolution;
 uniform vec2 u_mouse;
 uniform float u_time;
 
-float random (in vec2 _st) { 
-    return fract(sin(dot(_st.xy,
+float random (in vec2 st) { 
+    return fract(sin(dot(st.xy,
                          vec2(12.9898,78.233)))* 
         43758.5453123);
 }
 
 // Based on Morgan McGuire @morgan3d
 // https://www.shadertoy.com/view/4dS3Wd
-float noise (in vec2 _st) {
-    vec2 i = floor(_st);
-    vec2 f = fract(_st);
+float noise (in vec2 st) {
+    vec2 i = floor(st);
+    vec2 f = fract(st);
 
     // Four corners in 2D of a tile
     float a = random(i);
@@ -34,18 +34,18 @@ float noise (in vec2 _st) {
             (d - b) * u.x * u.y;
 }
 
-mat2 rotate2d(float _angle){
-    return mat2(cos(_angle),-sin(_angle),
-                sin(_angle),cos(_angle));
+mat2 rotate2d(float angle){
+    return mat2(cos(angle),-sin(angle),
+                sin(angle),cos(angle));
 }
 
-float lines(in vec2 _pos, float _angle, float _b){
+float lines(in vec2 pos, float angle, float b){
     float scale = 10.0;
-    _pos *= scale;
-    _pos = rotate2d( _angle ) * _pos;
+    pos *= scale;
+    pos = rotate2d( angle ) * pos;
     return smoothstep(0.0,
-                    0.5+_b*0.5,
-                    abs((sin(_pos.x*3.1415)+_b*2.0))*0.5);
+                    0.5+b*0.5,
+                    abs((sin(pos.x*3.1415)+b*2.0))*0.5);
 }
 
 void main() {

12/1d-fbm.frag

@@ -6,33 +6,33 @@ uniform vec2 u_resolution;
 uniform vec2 u_mouse;
 uniform float u_time;
 
-float plot(vec2 _st, float _pct){
-  return  smoothstep( _pct-0.01, _pct, _st.y) - 
-          smoothstep( _pct, _pct+0.01, _st.y);
+float plot(vec2 st, float pct){
+  return  smoothstep( pct-0.01, pct, st.y) - 
+          smoothstep( pct, pct+0.01, st.y);
 }
 
-float random (in float _x) {
-    return fract(sin(_x)*1e4);
+float random (in float x) {
+    return fract(sin(x)*1e4);
 }
 
 // Based on Morgan McGuire @morgan3d
 // https://www.shadertoy.com/view/4dS3Wd
-float noise (in float _x) {
-    float i = floor(_x);
-    float f = fract(_x);
+float noise (in float x) {
+    float i = floor(x);
+    float f = fract(x);
     float u = f * f * (3.0 - 2.0 * f);
     return mix(random(i), random(i + 1.0), u);
 }
 
 #define NUM_OCTAVES 5
 
-float fbm ( in float _x) {
+float fbm ( in float x) {
     float v = 0.0;
     float a = 0.5;
     float shift = float(100.0);
     for (int i = 0; i < NUM_OCTAVES; ++i) {
-        v += a * noise(_x);
-        _x = _x * 2.0 + shift;
+        v += a * noise(x);
+        x = x * 2.0 + shift;
         a *= 0.5;
     }
     return v;

12/2d-fbm.frag

@@ -6,17 +6,17 @@ uniform vec2 u_resolution;
 uniform vec2 u_mouse;
 uniform float u_time;
 
-float random (in vec2 _st) { 
-    return fract(sin(dot(_st.xy,
+float random (in vec2 st) { 
+    return fract(sin(dot(st.xy,
                          vec2(12.9898,78.233)))* 
         43758.5453123);
 }
 
 // Based on Morgan McGuire @morgan3d
 // https://www.shadertoy.com/view/4dS3Wd
-float noise (in vec2 _st) {
-    vec2 i = floor(_st);
-    vec2 f = fract(_st);
+float noise (in vec2 st) {
+    vec2 i = floor(st);
+    vec2 f = fract(st);
 
     // Four corners in 2D of a tile
     float a = random(i);
@@ -33,7 +33,7 @@ float noise (in vec2 _st) {
 
 #define NUM_OCTAVES 5
 
-float fbm ( in vec2 _st) {
+float fbm ( in vec2 st) {
     float v = 0.0;
     float a = 0.5;
     vec2 shift = vec2(100.0);
@@ -41,8 +41,8 @@ float fbm ( in vec2 _st) {
     mat2 rot = mat2(cos(0.5), sin(0.5), 
                     -sin(0.5), cos(0.50));
     for (int i = 0; i < NUM_OCTAVES; ++i) {
-        v += a * noise(_st);
-        _st = rot * _st * 2.0 + shift;
+        v += a * noise(st);
+        st = rot * st * 2.0 + shift;
         a *= 0.5;
     }
     return v;

12/noise.frag

@@ -3,12 +3,13 @@ precision mediump float;
 #endif
 
 uniform vec2 u_resolution;
+uniform vec2 u_mouse;
 uniform float u_time;
 
 // Based on Morgan
 // https://www.shadertoy.com/view/4dS3Wd
-float random (in float _x) {
-    return fract(sin(_x)*1e4);
+float random (in float x) {
+    return fract(sin(x)*1e4);
 }
 
 float random (in vec2 _st) { 
@@ -16,9 +17,9 @@ float random (in vec2 _st) {
     return fract( 1e4 * sin(17.0 * _st.x + _st.y * 0.1) * (0.1 + abs(sin(_st.y * 13.0 + _st.x)))); 
 }
 
-float noise (in float _x) {
-    float i = floor(_x);
-    float f = fract(_x);
+float noise (in float x) {
+    float i = floor(x);
+    float f = fract(x);
     float u = f * f * (3.0 - 2.0 * f);
     return mix(random(i), random(i + 1.0), u);
 }
@@ -63,13 +64,13 @@ float noise (in vec3 _p) {
 
 #define NUM_OCTAVES 5
 
-float fbm ( in float _x) {
+float fbm ( in float x) {
     float v = 0.0;
     float a = 0.5;
     float shift = float(100.0);
     for (int i = 0; i < NUM_OCTAVES; ++i) {
-        v += a * noise(_x);
-        _x = _x * 2.0 + shift;
+        v += a * noise(x);
+        x = x * 2.0 + shift;
         a *= 0.5;
     }
     return v;

14/README.md

@@ -1,15 +1,39 @@
 # Image processing
 
-Graphic cards (GPUs) have the ability to chop images (called a *texture*) into smaller fragments, which are then fed to the active threads. For this task, the graphics cards are equipped with special accelerated memory types which require the image to be uploaded before being used. Like vegetables in restaurant kitchens, the elements have to be chopped and ready before cooking starts. ****we need to talk about this paragraph and improve it ****
+![](01.jpg)
 
-## What is a texture?
+## Textures, the new way of doing images
 
-Coming soon…
+Graphic cards (GPUs) have special memory types for images. Usually on CPUs images are stores as arrays of bites but on GPUs store images as ```sampler2D``` which is more like a table (or matrix) of floating point vectors. More interestingly is that the values of this *table* of vectors are continously. That means that value between pixels are interpolated in a low level.
 
-![fabric](05.jpg)
+In order to use this feature we first need to *upload* the image from the CPU to the GPU, to then pass the ```id``` of the texture to the right [```uniform```](../05). All that happens outside the shader. 
+
+Once the texture is loaded and linked to a valid ```uniform sampler2D``` you can ask for specific color value at specific coordinates (formated on a [```vec2```](index.html#vec2.md) variable) usin the [```texture2D()```](index.html#texture2D.md) function which will return a color formated on a [```vec4```](index.html#vec4.md) variable.
+
+```glsl
+vec4 texture2D(sampler2D texture, vec2 coordinates)  
+```
+
+Check the following code to see how this works inside a shader:
 
 <div class="codeAndCanvas" data="texture.frag" data-imgs="kanagawa.jpg"></div>
 
-## Playing
+Try:
+
+* Scaling the previus texture by half.
+* Rotating the previus texture 90 degrees.
+* Hooking the mouse position to the coordenates to move it.
+
+If you pay attention you will note that the coordinates for the texture are normalized! What a surprise right?
+
+Why you should be excited about textures? Well first of all forget about the sad 255 values for channel, once your image is trasformed into a ```uniform sampler2D``` you have all the values between 0.0 and 1.0 (depending on what you set the ```precision``` to ). That's why shaders can make really beatiful post-processing effects. 
+
+Second, the [```vec2()```](index.html#vec2.md) means you can get values even between pixels. As we said before the textures are a continum. This means that if you set up your texture correctly you can ask for values all arround the surface of your image and the values will smoothly vary from pixel to pixel with no jumps! 
+
+Finnally, you can setup your image to repeat in the edges, so if you give values over or lower of the normalized 0.0 and 1.0, the values will wrap around starting over.
+
+All this features makes your images more like an infinit spandex fabric. You can streach and shrinks your texture without noticing the grid of bites they originally where compose of or the ends of it. To experience this take a look to the following code where we distort a texture using [the noise function we already made](../11/).
+
+<div class="codeAndCanvas" data="texture-noise.frag" data-imgs="kanagawa.jpg"></div>
 
-<div class="codeAndCanvas" data="texture-noise.frag" data-imgs="kanagawa.jpg"></div>
+In the next chapters we will learn how to do some image processing using shaders. You will note that finnaly the complexity of shader makes sense, because was in a big sense designed to do this type of process. We will start doing some image operations!

14/texture-noise.frag

@@ -8,19 +8,20 @@ uniform sampler2D u_tex0;
 uniform vec2 u_tex0Resolution;
 
 uniform vec2 u_resolution;
+uniform vec2 u_mouse;
 uniform float u_time;
 
 // Based on Morgan
 // https://www.shadertoy.com/view/4dS3Wd
-float random (in vec2 _st) { 
-    return fract(sin(dot(_st.xy,
+float random (in vec2 st) { 
+    return fract(sin(dot(st.xy,
                          vec2(12.9898,78.233)))* 
         43758.5453123);
 }
 
-float noise (in vec2 _st) {
-    vec2 i = floor(_st);
-    vec2 f = fract(_st);
+float noise (in vec2 st) {
+    vec2 i = floor(st);
+    vec2 f = fract(st);
 
     // Four corners in 2D of a tile
     float a = random(i);

14/texture.frag

@@ -6,6 +6,7 @@ uniform sampler2D u_tex0;
 uniform vec2 u_tex0Resolution;
 
 uniform vec2 u_resolution;
+uniform vec2 u_mouse;
 uniform float u_time;
 
 void main () {

glossary/abs.md

@@ -1,5 +1,5 @@
 ## Abs
-Return the absolute value of the parameter
+Return the absolute value of the parameter.
 
 ### Declaration
 ```glsl

glossary/uniform.md

@@ -0,0 +1,4 @@
+## Uniform
+
+### See
+[Chapter 03: Uniforms](../05/)