[examples] Add shaders_game_of_life (#5394)

* [examples] Add `shaders_game_of_life`

* Declaration hides another variable same name

Author: JordSant

examples/shaders/resources/game_of_life/acorn.png

@@ -0,0 +1,44 @@
+#version 100
+
+precision highp float;
+
+// Input vertex attributes (from vertex shader)
+varying vec2 fragTexCoord;
+varying vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform vec4 colDiffuse;
+
+// Input size in pixels of the textures
+uniform vec2 resolution;
+
+void main()
+{
+    // Size of one pixel in texture coordinates (from 0.0 to 1.0)
+    float x = 1.0/resolution.x;
+    float y = 1.0/resolution.y;
+
+    // Status of the current cell (1 = alive, 0 = dead)
+    int origValue = (texture2D(texture0, fragTexCoord).r < 0.1)? 1 : 0;
+
+    // Sum of alive neighbors
+    int sumValue = (texture2D(texture0, vec2(fragTexCoord.x - x, fragTexCoord.y - y)).r < 0.1)? 1 : 0;  // Top-left
+    sumValue    += (texture2D(texture0, vec2(fragTexCoord.x - x, fragTexCoord.y    )).r < 0.1)? 1 : 0;  // Top
+    sumValue    += (texture2D(texture0, vec2(fragTexCoord.x - x, fragTexCoord.y + y)).r < 0.1)? 1 : 0;  // Top-right
+
+    sumValue    += (texture2D(texture0, vec2(fragTexCoord.x,     fragTexCoord.y - y)).r < 0.1)? 1 : 0;  // Left
+    sumValue    += (texture2D(texture0, vec2(fragTexCoord.x,     fragTexCoord.y + y)).r < 0.1)? 1 : 0;  // Right
+
+    sumValue    += (texture2D(texture0, vec2(fragTexCoord.x + x, fragTexCoord.y - y)).r < 0.1)? 1 : 0;  // Bottom-left
+    sumValue    += (texture2D(texture0, vec2(fragTexCoord.x + x, fragTexCoord.y    )).r < 0.1)? 1 : 0;  // Bottom
+    sumValue    += (texture2D(texture0, vec2(fragTexCoord.x + x, fragTexCoord.y + y)).r < 0.1)? 1 : 0;  // Bottom-right
+
+    // Game of life rules:
+    // Current cell remains alive when 2 or 3 neighbors are alive, dies otherwise
+    // Current cell goes from dead to alive when exactly 3 neighbors are alive
+    if ((origValue == 1 && sumValue == 2) || sumValue == 3)
+        gl_FragColor = vec4(0.0, 0.0, 0.0, 255.0);  // Alive: draw the pixel black
+    else
+        gl_FragColor = fragColor;                   // Dead: draw the pixel with the background color, RAYWHITE
+}