Blending using multiply

[Adversus]

I want to blend a quad to the framebuffer using this but I can't figure out what I need to do.

Basically what I want to happen is if I blend a white quad on an area of the framebuffer then there's no change. If it's black then the result is black i.e. the source is multiplied by the dest.

I looked at ag for EMT_ONETEXTURE_BLEND, but the equation doesn't seem to be able to give me what I want

from the docs it says:

( BlendFactor ) BlendFunc = source * sourceFactor + dest * destFactor.

Any ideas or do I have to write a material to do this?

[devsh]

glBlendFunc()

you need to stick a native openGL call in OnSetMaterial in your shadercall-back

RECAP, blendign function:

srcCol*srcFact+destCol*destFact

srcFact and destFact can be any of GL_ONE,ZERO,SRC_ALPHA,DST_ALPHA,SRC_COL,DST_COL and OBVIOUSLY the ONE_MINUS variants of the last 4

the source factor (srcFact) need to be THE DESTINATION COLOR
then your dest factor can be GL_ZERO

[Adversus]

Offcourse, sorry didn't have that much sleep last night

For some reason I just assumed you could only pass dest enums into dest factors etc.

Thanks.

[Mel]

You don't need any shader for that. Besides, Irrlicht has its own function to pack the operation for the EMT_ONETEXTURE_BLEND which is driver independent

f32 irr::video::pack_texureBlendFunc( const E_BLEND_FACTOR srcFact,const E_BLEND_FACTOR dstFact,const E_MODULATE_FUNC modulate, const u32 alphaSource );

That uses the enums you were referring to. Then, you have to set the result of the function on the MaterialTypeParam on the material you are using to draw the quad, and you'd be done.

[Vectrotek]

I have seeked but I have not found!

Code: Select all

 
    Material.MaterialTypeParam = video::pack_texureBlendFunc(  // pack_texureBlendFunc
        video::EBF_SRC_ALPHA, 
        video::EBF_ONE_MINUS_SRC_ALPHA,
        video::EMFN_MODULATE_1X, 
        video::EAS_TEXTURE | video::EAS_VERTEX_COLOR); 
 
 

What would be a good replacement for the code above using Irrlicht 1.8.3 or 1.8.4 ?

Code: Select all

video::pack_texureBlendFunc

seems to be a problem..

[Vectrotek]

[Vectrotek]

2012 material..
http://irrlicht.sourceforge.net/forum/v ... ip#p250538
The project is downloadable here:
http://www.van-helsing-band.de/irrlicht ... nenode.zip
Please help.. (lens flare in another example works..)

[hendu]

textureBlendFunc. May also need to enable blending in the material (mat.BlendOperation = EBO_ADD).

[Vectrotek]

Thanks! I forgot to mention that "pack_texureBlendFunc" is not available under Irrlicht 1.8.3.
I was wondering if there is another way of using what is available in the standard Irrlicht version 1.8.3 (or 4)
to achieve the same thing.

Ive tried all sorts of combinations like..

Code: Select all

 
    // ORIGINAL..
    // Material.MaterialType = video::EMT_ONETEXTURE_BLEND; // Old line..
    Material.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL; // My new Line..
    // ORIGINAL..
    /* // NOT available under Irrlicht 1.8.3 (comes from 1.8.0-alpha)
    Material.MaterialTypeParam
       = video::pack_texureBlendFunc(video::EBF_SRC_ALPHA, 
                                     video::EBF_ONE_MINUS_SRC_ALPHA,
                                     video::EMFN_MODULATE_1X, 
                                     video::EAS_TEXTURE | video::EAS_VERTEX_COLOR); // ???
    //*/
    
    // Possible substitutes?
    //  Material.MaterialTypeParam = video::EBF_SRC_ALPHA ;
    // Material.MaterialTypeParam = video::EBF_ONE_MINUS_SRC_ALPHA ;
    //** Material.MaterialTypeParam = video::EMFN_MODULATE; // ???????
    // Material.MaterialTypeParam = video::EAS_TEXTURE ; // NOPE!!
    // Material.MaterialTypeParam = video::EAS_VERTEX_COLOR;
    // Material.MaterialTypeParam = video::EMT_ONETEXTURE_BLEND; // NOPE
 
    // Tests A..
    // Material.MaterialTypeParam =  video::EBF_ZERO;                         // src & dest (0, 0, 0, 0)
    // Material.MaterialTypeParam =  video::EBF_ONE;                  // src & dest (1, 1, 1, 1)
    // Material.MaterialTypeParam =  video::EBF_DST_COLOR;            // src (destR, destG, destB, destA)
    // Material.MaterialTypeParam =  video::EBF_ONE_MINUS_DST_COLOR;  // src (1-destR, 1-destG, 1-destB, 1-destA)
    // Material.MaterialTypeParam =  video::EBF_SRC_COLOR;            // dest (srcR, srcG, srcB, srcA)
    // Material.MaterialTypeParam =  video::EBF_ONE_MINUS_SRC_COLOR;  // dest (1-srcR, 1-srcG, 1-srcB, 1-srcA)
    // Material.MaterialTypeParam =  video::EBF_SRC_ALPHA;            // src & dest (srcA, srcA, srcA, srcA)
    // Material.MaterialTypeParam =  video::EBF_ONE_MINUS_SRC_ALPHA;  // src & dest (1-srcA, 1-srcA, 1-srcA, 1-srcA)
    // Material.MaterialTypeParam =  video::EBF_DST_ALPHA;            // src & dest  (destA, destA, destA, destA)
    // Material.MaterialTypeParam =  video::EBF_ONE_MINUS_DST_ALPHA;  // src & dest (1-destA, 1-destA, 1-destA, 1-destA)
    // Material.MaterialTypeParam =  video::EBF_SRC_ALPHA_SATURATE;   // src (min(srcA, 1-destA), idem, ...)
 
 

[Vectrotek]

I got the alpha working, but when I compare the Original EXE with my own then I see that there is a noticeable border at the end in the horison.

[hendu]

Add the missing T. Like I highlighted in bold.

[Vectrotek]

This may have something to do with the "COLORS" (or aplhas of those colors) in..

Code: Select all

 
   f32 factor = InnerRadius / OuterRadius;     // calculate the factor (inner ring)
   // first vertex is the center of the cloud dome
   InnerVertices[0] = video::S3DVertex(0, CenterHeight, 0, 0.f, -1.f, 0.f, CenterColor, 0, 0);
   // now calculate the vertices on the inner ring and on the outer ring
   for (s32 i=0; i<CLOUDSUBDIV; i++)
    {edge = edge.rotateBy(360.f/(f32)CLOUDSUBDIV, core::vector2d<f32>(0.f, 0.f));
        InnerVertices[i+1] = video::S3DVertex(edge.X*factor, InnerHeight, edge.Y*factor, 0.f, -1.f, 0.f, InnerColor, edge.X*factor, edge.Y*factor);
        OuterVertices[i] = InnerVertices[i+1];
        OuterVertices[i+CLOUDSUBDIV] = video::S3DVertex(edge.X, OuterHeight, edge.Y, 0.f, -1.f, 0.f, OuterColor, edge.X, edge.Y);
    }
 

But how do we get these colors to show?

[Vectrotek]

Which missing "T"?

[Vectrotek]

I don't see no Bold T!

[Vectrotek]

Aaaaaargh!!!! pack_textureBlendFunc "t" Gotit!!!!