[examples] Add core_monitor_change and shaders_ascii_rendering (#293)

* Add monitor_change example

* Adding `core_monitor_change` and `shaders_ascii_rendering` examples

examples/shaders/resources/LICENSE.md

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+| resource           | author        | licence | notes |
+| :----------------- | :-----------: | :------ | :---- |
+| fudesumi.png       | [Eiden Marsal](https://www.artstation.com/marshall_z)  | [CC-BY-NC](https://creativecommons.org/licenses/by-nc/4.0/)  | - |
+| raysan.png         | [@raysan5](https://github.com/raysan5)      | [CC0](https://creativecommons.org/publicdomain/zero/1.0/)   | - |

examples/shaders/resources/shaders/glsl100/ascii.fs

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+#version 100
+
+precision mediump float;
+
+// Input from the vertex shader
+varying vec2 fragTexCoord;
+
+// Output color for the screen
+varying vec4 finalColor;
+
+uniform sampler2D texture0;
+uniform vec2 resolution;
+
+// Fontsize less then 9 may be not complete
+uniform float fontSize;
+
+float GreyScale(in vec3 col)
+{
+    return dot(col, vec3(0.2126, 0.7152, 0.0722));
+}
+
+float GetCharacter(float n, vec2 p)
+{
+    p = floor(p*vec2(-4.0, 4.0) + 2.5);
+
+    // Check if the calculated coordinate is inside the 5x5 grid (from 0.0 to 4.0)
+    if (clamp(p.x, 0.0, 4.0) == p.x && clamp(p.y, 0.0, 4.0) == p.y)
+    {
+        float a = floor(p.x + 0.5) + 5.0*floor(p.y + 0.5);
+
+        // This checked if the 'a'-th bit of 'n' was set
+        float shiftedN = floor(n/pow(2.0, a));
+
+        if (mod(shiftedN, 2.0) == 1.0)
+        {
+            return 1.0; // The bit is on
+        }
+    }
+
+    return 0.0; // The bit is off, or we are outside the grid
+}
+
+// -----------------------------------------------------------------------------
+// Main shader logic
+// -----------------------------------------------------------------------------
+
+void main() 
+{
+    vec2 charPixelSize = vec2(fontSize, fontSize);
+    vec2 uvCellSize = charPixelSize/resolution;
+
+    // The cell size is based on the fontSize set by application
+    vec2 cellUV = floor(fragTexCoord/uvCellSize)*uvCellSize;
+
+    vec3 cellColor = texture2D(texture0, cellUV).rgb;
+
+    // Gray is used to define what character will be selected to draw
+    float gray = GreyScale(cellColor);
+
+	float n =  4096.0;
+    
+    // Character set from https://www.shadertoy.com/view/lssGDj
+    // Create new bitmaps https://thrill-project.com/archiv/coding/bitmap/
+    if (gray > 0.2) n = 65600.0;    // :
+	if (gray > 0.3) n = 18725316.0; // v
+	if (gray > 0.4) n = 15255086.0; // o 
+	if (gray > 0.5) n = 13121101.0; // &
+	if (gray > 0.6) n = 15252014.0; // 8
+	if (gray > 0.7) n = 13195790.0; // @
+	if (gray > 0.8) n = 11512810.0; // #
+
+    vec2 localUV = (fragTexCoord - cellUV)/uvCellSize; // Range [0.0, 1.0]
+
+    vec2 p = localUV*2.0 - 1.0; // Range [-1.0, 1.0]
+
+    // cellColor and charShape will define the color of the char
+    vec3 color = cellColor*GetCharacter(n, p);
+
+    gl_FragColor = vec4(color, 1.0);
+}

examples/shaders/resources/shaders/glsl120/ascii.fs

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+#version 120
+
+// Input from the vertex shader
+varying vec2 fragTexCoord;
+
+// Output color for the screen
+varying vec4 finalColor;
+
+uniform sampler2D texture0;
+uniform vec2 resolution;
+
+// Fontsize less then 9 may be not complete
+uniform float fontSize;
+
+float GreyScale(in vec3 col)
+{
+    return dot(col, vec3(0.2126, 0.7152, 0.0722));
+}
+
+float GetCharacter(float n, vec2 p)
+{
+    p = floor(p*vec2(-4.0, 4.0) + 2.5);
+
+    // Check if the calculated coordinate is inside the 5x5 grid (from 0.0 to 4.0)
+    if (clamp(p.x, 0.0, 4.0) == p.x && clamp(p.y, 0.0, 4.0) == p.y)
+    {
+        float a = floor(p.x + 0.5) + 5.0*floor(p.y + 0.5);
+
+        // This checked if the 'a'-th bit of 'n' was set
+        float shiftedN = floor(n/pow(2.0, a));
+
+        if (mod(shiftedN, 2.0) == 1.0)
+        {
+            return 1.0; // The bit is on
+        }
+    }
+
+    return 0.0; // The bit is off, or we are outside the grid
+}
+
+// -----------------------------------------------------------------------------
+// Main shader logic
+// -----------------------------------------------------------------------------
+
+void main() 
+{
+    vec2 charPixelSize = vec2(fontSize, fontSize);
+    vec2 uvCellSize = charPixelSize / resolution;
+
+    // The cell size is based on the fontSize set by application
+    vec2 cellUV = floor(fragTexCoord / uvCellSize)*uvCellSize;
+
+    vec3 cellColor = texture2D(texture0, cellUV).rgb;
+
+    // Gray is used to define what character will be selected to draw
+    float gray = GreyScale(cellColor);
+
+	float n =  4096.0;
+    
+    // Character set from https://www.shadertoy.com/view/lssGDj
+    // Create new bitmaps https://thrill-project.com/archiv/coding/bitmap/
+    if (gray > 0.2) n = 65600.0;    // :
+	if (gray > 0.3) n = 18725316.0; // v
+	if (gray > 0.4) n = 15255086.0; // o 
+	if (gray > 0.5) n = 13121101.0; // &
+	if (gray > 0.6) n = 15252014.0; // 8
+	if (gray > 0.7) n = 13195790.0; // @
+	if (gray > 0.8) n = 11512810.0; // #
+
+    vec2 localUV = (fragTexCoord - cellUV)/uvCellSize; // Range [0.0, 1.0]
+
+    vec2 p = localUV*2.0 - 1.0; // Range [-1.0, 1.0]
+
+    // cellColor and charShape will define the color of the char
+    vec3 color = cellColor*GetCharacter(n, p);
+
+    gl_FragColor = vec4(color, 1.0);
+}

examples/shaders/resources/shaders/glsl330/ascii.fs

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+#version 330
+
+// Input from the vertex shader
+in vec2 fragTexCoord;
+
+// Output color for the screen
+out vec4 finalColor;
+
+uniform sampler2D texture0;
+uniform vec2 resolution;
+
+// Fontsize less then 9 may be not complete
+uniform float fontSize;
+
+float GreyScale(in vec3 col)
+{
+    return dot(col, vec3(0.2126, 0.7152, 0.0722));
+}
+
+float GetCharacter(int n, vec2 p)
+{
+	p = floor(p*vec2(-4.0, 4.0) + 2.5);
+	
+	// Check if the coordinate is inside the 5x5 grid (0 to 4)
+	if (clamp(p.x, 0.0, 4.0) == p.x && clamp(p.y, 0.0, 4.0) == p.y)
+    {
+        int a = int(round(p.x) + 5.0*round(p.y));
+        if (((n >> a) & 1) == 1)
+        {
+            return 1.0;
+        }
+    }
+
+	return 0.0; // The bit is off, or we are outside the grid
+}
+
+// -----------------------------------------------------------------------------
+// Main shader logic
+// -----------------------------------------------------------------------------
+
+void main() 
+{
+    vec2 charPixelSize = vec2(fontSize, fontSize);
+    vec2 uvCellSize = charPixelSize/resolution;
+
+    // The cell size is based on the fontSize set by application
+    vec2 cellUV = floor(fragTexCoord/uvCellSize)*uvCellSize;
+
+    vec3 cellColor = texture(texture0, cellUV).rgb;
+
+    // Gray is used to define what character will be selected to draw
+    float gray = GreyScale(cellColor);
+
+	int n =  4096;
+    
+    // Character set from https://www.shadertoy.com/view/lssGDj
+    // Create new bitmaps https://thrill-project.com/archiv/coding/bitmap/
+    if (gray > 0.2) n = 65600;    // :
+	if (gray > 0.3) n = 18725316; // v
+	if (gray > 0.4) n = 15255086; // o 
+	if (gray > 0.5) n = 13121101; // &
+	if (gray > 0.6) n = 15252014; // 8
+	if (gray > 0.7) n = 13195790; // @
+	if (gray > 0.8) n = 11512810; // #
+
+    vec2 localUV = (fragTexCoord - cellUV)/uvCellSize; // Range [0.0, 1.0]
+
+    vec2 p = localUV*2.0 - 1.0; // Range [-1.0, 1.0]
+
+    vec3 color = cellColor*GetCharacter(n, p);
+
+    finalColor = vec4(color, 1.0);
+}