[shader] Internal reflection / intersection with geometry given a point and a vector

[MinZe]

Hi, I want to do an internal reflection shader, and I need to check two things:

1. Check if with a given point, vector and maximum distance there is a face of my geometry in which the vector intersects with.

2. the face's normal.

Is there a way to do this?

Thanks.

[brianzinn]

#1. https://doc.babylonjs.com/babylon101/raycasts

var ray = new BABYLON.Ray(origin, direction, length);
var hit = scene.pickWithRay(ray);

You may need to do a multipick, if you want to go past meshes occluding.

#2.  I think you need to use the hit.faceId to get the normal of the face.  The normal of the hit is, I think, for the ray.

var normal = pickInfo.getNormal(...);

edit: Welcome to the forum!

[MinZe]

Thanks, but I wanted to say in the shader, I already know how to to a raycast using babylon's code.

[brianzinn]

I've only used the reflection probe:
https://doc.babylonjs.com/how_to/how_to_use_reflection_probes

That's generating a reflection cube map texture.  With just a point, vector, and normal (reflection angle) - you still need to account for other light sources and shadows as well. There are some shader gurus in the forum, but it would be helpful if you had a playground.

[Nabroski]

so i'm also not sure what is going on with this engine, take this as a template to go further https://www.babylonjs-playground.com/#6LGN7K#1

i think @NasimiAsl is the expert here.

[MinZe]

Thanks! generating a cubemap in realtime it's something that I needed too!

For the intersection with geometry, I think that If I pass the array of the geometry to the shader I can calculate the intersection between a point with a vector and a plane.

But If someone knows any method to do it, feel free to post it, as It's gonna help for sure.

[NasimiAsl]

hi  

just for start challenge  you wanna make something like diamond? or infinity self mirror?

[MinZe]

1 hour ago, NasimiAsl said:

hi  

just for start challenge  you wanna make something like diamond? or infinity self mirror?

More like a diamond

[NasimiAsl]

for step 1 : i just can make fake inner reflect ( i don't calculate inner position for yet )

so i use this pic

** if we can make some  real image from inside and make dark and white face ( calculate by normal direction )   we can close to real

for step 2 : make refract from this pic

http://www.babylonjs-playground.com/#7AIII8#45

step 3 : make reflect from last refract ( like 2 reflect  notice in real diamond we have infinity reflact but we do just some level)

https://www.babylonjs-playground.com/#7AIII8#46

step 4 : broke refract with  last result and use main environment map 

https://www.babylonjs-playground.com/#7AIII8#47

it is starter solution for make diamond  

add specular reflect 

https://www.babylonjs-playground.com/#7AIII8#48

 

 

[MinZe]

Thanks!

it's good enough to have until I've done the shader.  thanks for the help