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Snippet Slimey shader

Wingnut

Well-known member
3rd Party Module Dev
Tutorial Author
Joined
Jan 2, 2020
Messages
1,414
Slime shader is a useful example of how a shader works.

code.png


Screenshot.png

shader.cxs
Cerberus:
Import mojo2
Function Main()
    New MyApp
End

Class MyApp Extends App

    Field sourceImage : Image
    Field targetImage : Image
    Field canvas : Canvas
    Field effect : ShaderEffect
    Field value : Float
    Field timer:Float = 0
     
    Method OnCreate()
        sourceImage = Image.Load("slime.png",0,0,0)
        targetImage = New Image(sourceImage.Width,sourceImage.Height)
        effect = New ShaderEffect
        canvas = New Canvas
          SetUpdateRate 0
    End
   
    Method OnUpdate:Int()
         timer = Millisecs()/100.0
'         timer = MouseX()/100.0 ' Test using mouse
        Return 0
    End
   
    Method OnRender()
        canvas.Clear 0, 0.5, 1, 1  
        effect.SetValue value
        value = value + 0.01        
        effect.SetValue timer ' Pass the varialel timer to shader
        effect.Render sourceImage, sourceImage,targetImage
        canvas.DrawRect 0,0, 256*1,256*1,targetImage,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.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 ' Timer should be 0-1
    End
   
    Method Render:Void(source:Image,source2: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
shader.glsl
Code:
uniform sampler2D ColorTexture;
uniform float Timer;

void shader(){
// -------------------------------------------------------------------------------------------------
    // Get pixel coordinate
    vec2 uv=(b3d_ClipPosition.st/b3d_ClipPosition.w)*0.5+0.5 ;
    vec2 p = vec2(floor(uv.x*256.0), floor(uv.y*256.0)) ;

    // Process pixel coordinate
    // uv.y = 1.0 - uv.y;
    // uv.y = -uv.y;
    //
    uv.y += (cos((uv.y+(Timer*0.004))*45.0)*0.019) +
    (cos((uv.y+(Timer*0.01))*15.0)*0.002);
    //
    uv.x += (sin((uv.y+(Timer*0.007))*15.0)*0.029) +
    (sin((uv.y+(Timer*0.01))*15.0)*0.002);
   
    // Read pixel
    vec4 color = texture2D(ColorTexture,uv).rgba ;

    // Write pixel
    b3d_FragColor = color ;
// -------------------------------------------------------------------------------------------------
}
 

Attachments

  • Slimeshader.zip
    54.8 KB · Views: 84
Looks nice. But you can see it not working correctly on the right side:

1621842905557.png
 
That's the edge of the texture that inhibits the blob to become larger. You always want to have spare room around the object.
I was exploring how it added to the drip-effect sometimes.

Here's one I edited that will fit perfectly.

slime.png
 
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