Re: [x3dom-users] x3dom Multitexture - how to layer textures / multi layer texture alpha

[Chris R. <ch...@th...>]

 Thanks Timo - it's nearly working but comes out as a multiply blend for me

vec4 crate = texture2D(crateSampler, fragTexCoord);
vec4 text   = texture2D(textSampler,   fragTexCoord);
gl_FragColor = crate + text.rgb * text.a;


I suspect I need something like:

gl_FragColor = (crate * 1-text.a)  + (text.rgb * text.a);

But I'm not sure how to do it..


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Chris Ratcliffe / Animation / Graphics / Creative Code
44 (0) 7973 299 138 / ch...@th...

THE GUILD TV LTD / http://www.theguild.tv

On 23 November 2015 at 10:50, Sturm, Timo <tim...@ig...>
wrote:

> Something like that should work:
>
>     vec4 crate = texture2D(crateSampler, fragTexCoord);
>     vec4 text   = texture2D(textSampler,   fragTexCoord);
>     gl_FragColor = crate + text.rgb * text.a;
>
> Regards
> Timo
>
> Am 23.11.2015 um 11:01 schrieb Chris Ratcliffe:
>
> Hi,
> Apologies for asking what may seem an obvious question:
>
> I would like to layer two textures using multitexture:
>
> I can BLEND two textures using this command:
>
>    vec4 texCol0 = texture2D(Picture0, fragTexCoord);
>    vec4 texCol1 = texture2D(Picture1, fragTexCoord);
>    gl_FragColor = texCol0 * 0.5 + texCol1 * 0.5;
>
> How can I layer a top texture over the bottom using an alpha channel?
>
> For example - say I had a crate texture and I want to stencil some letters
> over the top
> of the crate as if the top layer had an alpha channel to reveal only the
> letters?
>
> Thanks for any advice
>
>
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