GLSL shader: set material uniforms

[AnatolParticipant]

Hi!

I’m still brand new at GLSL shaders and I’m trying to pass a value into a shader. So in the .glsl file I have this (simplified):

C++

uniform vec4 m_TestColor; void main(){ gl_FragColor=m_TestColor; }

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uniform vec4 m_TestColor;   void main(){ gl_FragColor=m_TestColor; }

From Monkey2 (in a class that extends Image) I’m trying to set m_TestColor via

Monkey

Local testColor := New Vec4f( 1.0, 0.0, 0.0, 1.0 ) Material.SetVec4f( "TestColor", testColor )

1 2	Local testColor := New Vec4f( 1.0, 0.0, 0.0, 1.0 ) Material.SetVec4f( "TestColor", testColor )

This causes an error: “Invalid uniform type 0 expecting 4”.

So how can I use SetVec4f or other UniformBlock methods? I assume I need those to pass something to a shader?

Thank you.

[Mark SiblyKeymaster]

Would need to see more code, it looks like it can’t find a uniform but I can’t really see how you’re setting things up etc.

It’s the right general idea though.

[edit]The shader related error message REALLY need some work! I’ll see what I can do here.[/edit]

[nerobotParticipant]

Don’t know what you do, but maybe my example will be useful.

I took mojo’s sprite shader, removed unused vars and added TestColor into fragment section.

Monkey

Namespace myapp #Import "<std>" #Import "<mojo>" Using std.. Using mojo.. Class MyWindow Extends Window Method New( title:String="Simple mojo app",width:Int=640,height:Int=480,flags:WindowFlags=Null ) Super.New( title,width,height,flags ) Local shader:=New Shader( "painter",shaderData,"" ) image=New Image( 100,100,,shader ) image.Handle=New Vec2f( .5 ) End Method OnRender( canvas:Canvas ) Override image.Material.SetColor( "TestColor",New Color( Mouse.Location.x/Float(Width),.5,Mouse.Location.y/Float(Height),1 ) ) App.RequestRender() canvas.DrawImage( image,Width/2,Height/2 ) End Field image:Image End Function Main() New AppInstance New MyWindow App.Run() End Const shaderData:="//@renderpasses 0,1,2 //@vertex attribute vec4 a_Position; uniform mat4 r_ModelViewProjectionMatrix; void main(){ gl_Position=r_ModelViewProjectionMatrix * a_Position; } //@fragment uniform vec4 m_TestColor; void main(){ gl_FragColor=m_TestColor; } "

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Namespace myapp   #Import "<std>" #Import "<mojo>"   Using std.. Using mojo..   Class MyWindow Extends Window   Method New( title:String="Simple mojo app",width:Int=640,height:Int=480,flags:WindowFlags=Null )   Super.New( title,width,height,flags ) Local shader:=New Shader( "painter",shaderData,"" ) image=New Image( 100,100,,shader ) image.Handle=New Vec2f( .5 ) End   Method OnRender( canvas:Canvas ) Override image.Material.SetColor( "TestColor",New Color( Mouse.Location.x/Float(Width),.5,Mouse.Location.y/Float(Height),1 ) ) App.RequestRender() canvas.DrawImage( image,Width/2,Height/2 ) End Field image:Image End   Function Main()   New AppInstance New MyWindow App.Run() End     Const shaderData:="//@renderpasses 0,1,2   //@vertex   attribute vec4 a_Position;   uniform mat4 r_ModelViewProjectionMatrix;   void main(){   gl_Position=r_ModelViewProjectionMatrix * a_Position; }   //@fragment   uniform vec4 m_TestColor;   void main(){   gl_FragColor=m_TestColor;   } "

[AnatolParticipant]

Thanks Mark and nerobot. Both answers were really helpful, plus it’s a face palm situation for me. It’s true that the shader couldn’t find the uniform. I set it in a method that was never called, so naturally the shader was expecting a Vec4f but probably had a null, or 0 vector if that even exists. I’m still confused enough by shaders that I was looking in the wrong place.

Actually I base my shader and ImageExtend on your sprite-masked shader, nerobot. That post was incredibly helpful. I just need to add a few “features” to the shader mask and I’m getting there one step at a time. Next up is a way to move/translate and scale the shader mask. I’ll see how I go and will share it in the forum.

[AnatolParticipant]

Sometimes it’s literally weeks until I find some more time for this, but for completeness’ sake and as I said I’ll share the result, I can simply send an offset value to the shader, e.g.

Monkey

CanvasLayer.Mask.Material.SetVec2f( "Resolution", New Vec2f( width, height ) ) ' app width/height CanvasLayer.Mask.Material.SetVec2f( "Offset", New Vec2f( App.MouseLocation.x, App.MouseLocation.y ) )

1 2	CanvasLayer.Mask.Material.SetVec2f( "Resolution", New Vec2f( width, height ) ) ' app width/height CanvasLayer.Mask.Material.SetVec2f( "Offset", New Vec2f( App.MouseLocation.x, App.MouseLocation.y ) )

which the shader will pick up and apply like this (simplified):

C++

uniform vec2 m_Resolution; uniform sampler2D m_ImageTexture0; uniform sampler2D m_MaskTexture; uniform vec4 m_HighlightColor; uniform vec2 m_Offset; void main(){ vec2 maskCoord = v_TexCoord0 - m_Offset / m_Resolution; vec4 maskColor = texture2D( m_MaskTexture, maskCoord ); vec4 imageColor = texture2D( m_ImageTexture0, v_TexCoord0 ); gl_FragColor.rgba = imageColor.rgba * m_HighlightColor.rgba; gl_FragColor.rgba *= ( maskColor.r + maskColor.g + maskColor.b ) / 3.0; #endif

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uniform vec2 m_Resolution; uniform sampler2D m_ImageTexture0; uniform sampler2D m_MaskTexture; uniform vec4 m_HighlightColor; uniform vec2 m_Offset;   void main(){ vec2 maskCoord = v_TexCoord0 - m_Offset / m_Resolution; vec4 maskColor = texture2D( m_MaskTexture, maskCoord ); vec4 imageColor = texture2D( m_ImageTexture0, v_TexCoord0 ); gl_FragColor.rgba = imageColor.rgba * m_HighlightColor.rgba; gl_FragColor.rgba *= ( maskColor.r + maskColor.g + maskColor.b ) / 3.0; #endif

For a full working example see this test on Github with a mask that moves based on mouse coordinates.

Here’s the shader code.

It’s not perfect but it shows how it works in principle.

[Author]

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