Vary amount of transparency: material or shaderParm howto..?

[Bikerdude]

I am trying to make some chinese lanterns -

• I have already created some two-sisded textures from existing paint textures,
• I added the transparent arg to the material def, but it appears to be 100%.
• So then I wehn to the wiki and found 'shaderParm3 and applied that to the FS model, but it dosent work.

So, can I vary the mount of transparency say by 50%? or is the shaderParm rout the right and I am just doing it wrong..?

 

ta.

[AluminumHaste]

AFAIK transparency will make anything with the pink colour 100% transparent, it's binary 100% opaque or 100% transparent.

 

Or, take the chain link fence texture in Doom 3 and see how it was done. It sounds like basically the same thing, you want parts to the transparent but opaque in others.

[nbohr1more]

The alpha keyword will set the percentage of transparency.

 

LOD entities use shaderParm3 to dynamically alter this but use alphatest to cut-off parts of the LOD texture:

 

http://wiki.thedarkmod.com/index.php?title=Alpha-fading

 

http://wiki.thedarkmod.com/index.php?title=List_of_shaderParm_variables

[Bikerdude]

The alpha keyword will set the percentage of transparency.

So tried gave that a go, no effect -

//paper texture for chinese lanterns - bikerdude

textures/darkmod/paint_paper/transparent/chinese_lantern_fancy_red
{

    surftype15
    description "cloth"
	
    twosided

    qer_editorimage textures/darkmod/paint_paper/wallpaper_fancy_red_ed
    {
    blend diffusemap
        map    		textures/darkmod/paint_paper/wallpaper_fancy_red
    alphatest 0.8
    }
    bumpmap         textures/darkmod/paint_paper/wallpaper_fancy_local

    {
        if ( parm11 > 0 )
        blend       gl_dst_color, gl_one
        map         _white
        rgb         0.40 * parm11
    }
    {
        if ( parm11 > 0 )
        blend       add
        map         textures/darkmod/paint_paper/wallpaper_fancy_red
        rgb         0.15 * parm11
    }

	// TDM Ambient Method Related 
	{							
		if (global5 == 1)		
		blend add				
		map				textures/darkmod/paint_paper/wallpaper_fancy_red		
		scale			1, 1		
		red				global2	
		green			global3	
		blue			global4	
	}							
}

[nbohr1more]

Alphatest is a hard cutoff. Invisible or not

Alpha is a smooth fading.

 

For the latter to work, you also need the translucent keyword AFAIK.

[Bikerdude]

So -

• changed 'alphatest 0.8' to 'alpha 0.8' no change,
• added the keyword transparency below twosided, and the textures apears tranparent but black
• reduced the alpha value, no change, texture still black.

 

Is is possible its not working because the texture in question dont have an alpha channel..? Scratch that I just check in Gimp at there is an alpha channel.

[nbohr1more]

It's "translucent" not "transparency".

 

Please post your updated material def.

 

[Bikerdude]

Inserting the arg 'translucent' fixed it! noice one fella.

[Bikerdude]

I spoke to soon, the alpha amount dosen't seem to have any effect on amount of transparency -

textures/darkmod/paint_paper/transparent/chinese_lantern_fancy_red
{

    surftype15
    description "cloth"
	
    twosided
    translucent

    qer_editorimage textures/darkmod/paint_paper/wallpaper_fancy_red_ed
    {
    blend diffusemap
        map    		textures/darkmod/paint_paper/wallpaper_fancy_red
    alpha 0.35
    }
    bumpmap         textures/darkmod/paint_paper/wallpaper_fancy_local

    {
        if ( parm11 > 0 )
        blend       gl_dst_color, gl_one
        map         _white
        rgb         0.40 * parm11
    }
    {
        if ( parm11 > 0 )
        blend       add
        map         textures/darkmod/paint_paper/wallpaper_fancy_red
        rgb         0.15 * parm11
    }

	// TDM Ambient Method Related 
	{							
		if (global5 == 1)		
		blend add				
		map				textures/darkmod/paint_paper/wallpaper_fancy_red		
		scale			1, 1		
		red				global2	
		green			global3	
		blue			global4	
	}							
}

[nbohr1more]

Ack!

 

I keep forgetting that alpha (not alphatest) material stages cannot be lit.

(Unlit meaning blend blend or blend add, cannot use blend diffusemap)

 

Under normal circumstances, you'd make a material like a glass shader but if you want the material to look like

fabric, you need to use the technique here:

 

http://forums.thedarkmod.com/topic/11515-real-translucency-anyone/

 

1) Export the Model

2) Vertex paint it with 50% weight everywhere

3) Texture is with a material like:

 
translucent/example
{

    // one set comprised of a normal map and diffuse map utilizing the vertexcolor keyword

    {
        blend    bumpmap
        map    normalmap.tga
        vertexcolor
    }
    {
        blend    diffusemap
        map    diffusemap.tga
        vertexcolor
    }

    // a second set using the same images with the inversevertexcolor keyword

    // the scale function here is "inverting" the normal map so that it catches light from the opposite side.

    {
        blend    bumpmap
        map    scale(normalmap.tga, 1, 1, 0, 1)
        inversevertexcolor
    }
    {
        blend    diffusemap
        map    diffusemap.tga
        inversevertexcolor
    }
 

[Bikerdude]

1) Export the Model

2) Vertex paint it with 50% weight everywhere

The video on that link dosen't appear to be working.

[nbohr1more]

Strange. It's just a YouTube video. Google "real translucency Doom 3" and you should find it amongst Rich_is_Bored's videos.

 

That said, there's no tutorial for the creation part. You need to know how to vertex paint in a modeling application.

[Bikerdude]

Sorry I means to say the tut link, and it looks Like I will have to see if I can figure out just enough to get this done in blender...

[rich_is_bored]

With a better understanding of fragment programs it occurs to me that it should be possible to assign vertex colors in a vfp. That's huge because it means you can make use of this effect on everything, not just models. I'll investigate this in the coming days and confirm.

[Bikerdude]

With a better understanding of fragment programs it occurs to me that it should be possible to assign vertex colors in a vfp. That's huge because it means you can make use of this effect on everything, not just models. I'll investigate this in the coming days and confirm.

Thanks Rich!

[Obsttorte]

instead of alpha use rgb parm3

 

Now you can alter the level of transparancy using the spawnarg shaderParm3

 

Note that you don't have the full bandwidth between invisible and opaque, the material is always translucent.

 

For more control you really need a shader program

[rich_is_bored]

Just wanted to report back. The following shader should assign a grey value to every vertex...

 

 

!!ARBvp1.0
OPTION ARB_position_invariant;

MOV result.color, {0.5, 0.5, 0.5, 1.0};

END

 

However, in TDM for reasons that escape me the vertex colors remain black. I've checked the console for errors and the shader compiles with no problem.

[nbohr1more]

I don't think you can alter a lit material that way?

 

You probably need to integrate this into a copy of our entire light vfp (probably where it gathers the vertex color)

then call that whole shebang from the material def?

 

Does it work with an unlit material?

[rich_is_bored]

It makes no difference.

[nbohr1more]

This was done to a brush, patch, or model?

[Bikerdude]

If your asking me, its the patch based part of the model..

[nbohr1more]

That was directed at Rich. If it's anything other than model that might tell us that the other formats do not respect the vertex color attribute

for some reason. I can't see how that would be the case but perhaps there's a driver bug.

[rich_is_bored]

I used r_materialOverride to apply it to everything.

[nbohr1more]

I guess I'll be trying out a few ideas this evening.

 

I keep forgetting about that cvar. Thanks for your input thus far.

[Bikerdude]

@Rib, thanks for your help on this.

 

@Nbohr, I look forward to trying out what you come up with.