Dither (for e.g. shadowing, invisibility, water transparency, invincibility effect)

[Jimmy]

Invincibility shader

Import mojo2
Function Main()
    New MyApp
End

Class MyApp Extends App

    Global image2:Image
    Global imagecanvas2:Canvas
    Field sourceImage : Image
    Field canvas : Canvas
    Field effect : ShaderEffect
    Field x : Int = 0
   
    Method OnCreate()
        sourceImage = Image.Load("256x256.png",0,0,0)
        effect = New ShaderEffect
        canvas = New Canvas
        image2=New Image(256,256,0,0,0)
        imagecanvas2=New Canvas(image2)
        SetUpdateRate 0
    End
   
    Method OnRender()
        canvas.Clear 0, 0.5, 1, 1
        canvas.DrawRect 0,0, 64,64

        If MouseDown(0)
            effect.Render sourceImage,image2 ; canvas.DrawRect x,0, 256*1,256*1,image2,0,0,256,256
        Else
             canvas.DrawRect x,0, 256*1,256*1,sourceImage,0,0,256,256
        Endif  

        x = x + 1 ; If x >= 512 Then x = x - 512
       
        canvas.Flush
    End

End

Class myShader Extends Shader

    Method New()
        Build(LoadString("shader.glsl"))
    End  
   
    Method OnInitMaterial:Void(material:Material)
        material.SetTexture "ColorTexture",Texture.White()
    End
   
    Function Instance:myShader()
        If Not _instance _instance=New myShader
        Return _instance
    End
   
    Private
    Global _instance:myShader
End

Class ShaderEffect

    Private
    Global _canvas:Canvas
    Field _material:Material
       
    Method New()
        If Not _canvas _canvas=New Canvas
        _material=New Material( myShader.Instance() )
    End
   
    Method Render:Void(source:Image,target:Image)
        _material.SetTexture "ColorTexture",source.Material.ColorTexture
        _canvas.Clear 0, 0, 0, 0
        _canvas.SetRenderTarget target
        _canvas.SetViewport 0,0,target.Width,target.Height
        _canvas.SetProjection2d 0,target.Width,0,target.Height
        _canvas.DrawRect 0,0,target.Width,target.Height,_material
        _canvas.Flush
    End
   
End

// Uniforms
uniform sampler2D ColorTexture; // sometimes called Texture0

// Constants
#define PI 3.14

// Functions
float luma(vec3 color) {
  return dot(color, vec3(0.299, 0.587, 0.114));
}

float luma(vec4 color) {
  return dot(color.rgb, vec3(0.299, 0.587, 0.114));
}

float dither2x2(vec2 position, float brightness) {
  int x = int(mod(position.x, 2.0));
  int y = int(mod(position.y, 2.0));
  int index = x + y * 2;
  float limit = 0.0;
  if (x < 8) {
    if (index == 0) limit = 0.25;
    if (index == 1) limit = 0.75;
    if (index == 2) limit = 1.00;
    if (index == 3) limit = 0.50;
  }
  return brightness < limit ? 0.0 : 1.0;
}

vec4 dither2x2(vec2 position, vec4 color) {
  return vec4(color.rgb * dither2x2(position, luma(color)), 1.0);
}

// Main function
void shader(){
// -------------------------------------------------------------------------------------------------
    // Get coordinate
    vec2 uv=(b3d_ClipPosition.st/b3d_ClipPosition.w)*0.5+0.5;    // 0.0 - 1.0
    vec2 p = vec2(floor(uv.x*256.0), floor(uv.y*256.0));        // 0 - 255

    // Read pixel
    vec4 color=texture2D(ColorTexture,uv).rgba;

    // Write pixel
    if (color.a != 0.0)
        b3d_FragColor = dither2x2(p, color.rgba) ; // Pixel shadow invisibility effect
    else
        b3d_FragColor = color ;
// -------------------------------------------------------------------------------------------------
}

Example how to use it :

 

[Jimmy]

After darkness comes light!

Import mojo2
Function Main()
    New MyApp
End

Class MyApp Extends App

    Global image2:Image
    Global imagecanvas2:Canvas
    Field sourceImage : Image
    Field sourceImage2 : Image
    Field targetImage : Image
    Field canvas : Canvas
    Field effect : ShaderEffect
    Field value : Float
    
    Method OnCreate()
        sourceImage = Image.Load("graphics.png",0,0,0)
        sourceImage2 = Image.Load("graphics2.png",0,0,0)
        targetImage = New Image(sourceImage.Width,sourceImage.Height)
        effect = New ShaderEffect
        canvas = New Canvas
        image2=New Image(256,256,0,0,0)
         imagecanvas2=New Canvas(image2)
         SetUpdateRate 0
    End
    
    Method OnRender()
        canvas.Clear
        value = value + 0.001
        If value > 100 Then value = 0

                effect.SetValue value
                value = value + 0.01
                effect.Render sourceImage, sourceImage2,image2 ; canvas.DrawRect 64,0, 256*2,256*2,image2,0,0,256,256
            
 
        canvas.Flush
    End

End

Class myShader Extends Shader

    Method New()
        Build(LoadString("shader.glsl"))
    End   
    
    Method OnInitMaterial:Void(material:Material)
        material.SetTexture "ColorTexture",Texture.White()
        material.SetTexture "ColorTexture2",Texture.White()
        material.SetScalar "Timer",1
    End
    
    Function Instance:myShader()
        If Not _instance _instance=New myShader
        Return _instance
    End
    
    Private
    Global _instance:myShader
End

Class ShaderEffect

    Private
    Global _canvas:Canvas
    Field _material:Material
        
    Method New()
        If Not _canvas _canvas=New Canvas
        _material=New Material( myShader.Instance() )
    End
    
    Method SetValue:Void( value:Float )
        _material.SetScalar "Timer",value
        _material.SetVector "color2",[1.0,0.0,0.0,1.0]
    End
    
    Method Render:Void(source:Image,source2:Image,target:Image)
        _material.SetTexture "ColorTexture",source.Material.ColorTexture
        _material.SetTexture "ColorTexture2",source2.Material.ColorTexture
        _canvas.Clear 0, 0, 0, 0
        _canvas.SetRenderTarget target
        _canvas.SetViewport 0,0,target.Width,target.Height
        _canvas.SetProjection2d 0,target.Width,0,target.Height
        _canvas.DrawRect 0,0,target.Width,target.Height,_material
        _canvas.Flush
    End
    
End

// Uniforms
uniform sampler2D ColorTexture;
uniform float Timer;

// Main function
void shader(){
// -------------------------------------------------------------------------------------------------
// Get coordinate
vec2 uv=(b3d_ClipPosition.st/b3d_ClipPosition.w)*0.5+0.5;    // 0.0 - 1.0
vec2 p = vec2(floor(uv.x*256.0), floor(uv.y*256.0));        // 0 - 255

    // Read pixel
    vec4 color=texture2D(ColorTexture,uv).rgba;

  vec3 c1 = vec3(0.0, 0.3, 0.5);
  vec3 c2 = vec3(0.5, 0.0, 0.3);
  float f = 0.0;
  float g = 0.0;
  float h = 0.0;
  float PI = 3.14159265;
  for(float i = 0.0; i < 63.0; i++){
    if (floor(0.5 * 64.0) < i)
      break;
    float s = sin(Timer + i * PI / 16.0) * 0.8;
    float c = cos(Timer + i * PI / 16.0) * 0.8;
    float d = abs(uv.x - 0.2 + c);
    float e = abs(uv.y - 0.2 + s);
    f += 0.001 / d;
    g += 0.001 / e;
    h += 0.00003 / (d * e);
  }

// Write pixel
b3d_FragColor = vec4(f * c1 + g * c2 + vec3(h), 1.0);
// -------------------------------------------------------------------------------------------------
}

 

[MikeHart]

Cool stuff. Self made or from a tutorial?