Discovering Fake Caustics in Blender

it's very late i just was about to end my day and then i just came across this way of making caustics in blender like this the lighting just looks really interesting and i'm just surprised at how quick this was to set up i just have to share this before i forget it so here's a render i did at 5 000 samples and you can just see the the light place just super nicely on the ground and i haven't even tried to animate this yet i have made the nodes set up to be able to do it but it just takes so long to render you can just see how fantastic this is going to look rendered okay so i'm going to try and use the shading tab yeah let's make a new material let's just call it casual caustics and uh let's give it an emission shader the thing here is to use the voronoi texture it's just a fantastic texture so add a voronoi texture connect the distance you know what we're going to make a plane instead yeah there we go and let's scale this down and you can see already it sort of feels it has something to do with liquids and refractions and i i think it's really interesting already but what we want to do here is we want to take two voronoi textures and we want to take the difference between them and then we want to just make tiny adjustments and it's super efficient so duplicate the voronoi texture and add a mix rgb node and set the mix type to difference and now when we set this to 1 it should go completely black perfect that means that these are identical so now we can change for example the scale and this is sort of the difference between these two let's set both of them to 4d and let's set this value to smooth f1 instead of just f1 set both of them to smooth f1 and now the whole trick here is to take the smoothness value and just see that oh my god it's already happening so there's the difference in the smoothness is what we are trying to control and a really nice way to control it is to add a value node so input value and connect this to smoothness in both of them and we can press f2 to just rename this to smoothness and since this controls both of them they're exactly the same which is perfect so now let's add a math node to just one of them let's set this to add and let's set it to point and now we can sort of increase this smoothness let me increase the brightness here so we can see it a bit easier really cool and you can make all types of controllers so you can take this one and just let's name this scale and let's make another one randomness connect these scale into the scale i'm probably looking like a crazy person just in the dark but i just have to share this because it's just it's so fascinating let's increase the scale and the randomness just makes this look so look at that we're not ready yet there's one final thing we need to adjust and that is in this color we need to add a color ramp node and let's increase the contrast and let's set it to b spline look at this look at all these details you can make another black value if you like so you get it even more contrasty fantastic look at that i just love this texture it's so cool you know what you can add one more and call this evolution and let's set this to connect it to the w you can hold down shift and you can change this value and this is basically going to be our effect let's dial down the randomness a little bit or maybe up yeah okay perfect so now here comes the trick how do we make this 2d texture into a light source this is the cool part oh yeah let's save this you see i've tried this a bunch of times so under material oh you can probably don't see this so under material properties let's click this shield button and let's just cross this out and make a new material set this to diffuse let's go back to the caustics material and let's split our viewport and let's set this to shader editor select everything by pressing a and ctrl c to just copy all of them and now let's make a light set to spotlight and let's move it on the z-axis the ground plane let's set the material back to just ground the diffuse material we already made let's select the light click use nodes if you're in the shader editor you can click use nodes and you can press ctrl v and now we can paste this entire texture into our light and delete the material output and set the emission to the surface let's set this to render view oh the light is way too weak so let's set it to ten thousand what hundred thousand i don't understand why this isn't working what's wrong here oh yes there's one important thing uh connect this back again let's delete the old stuff this vector we have forgotten to populate it so let's take this vector and let's make a texture coordinate node because we need to access this normal data and then let's make a vector and then mapping and then let's connect these vector values to this one and connect the normal to vector and there we go look at this beauty the thing is you have to go on the light settings and lower the radius so let's set this to 0.1 and already it's getting a lot sharper so this is sort of the sharpness value we're adjusting set our world strength to zero oh yeah and now we have to go to in the shader editor let's set it to world and let's just get rid of the background and shift a to make a volume scatter shader and plug this into the volume let's set the density to 0.1 look at that now let's add a monkey shift a look at this it just renders so slowly there it is so the trick is to make your light have this setup this is the takeaway from this tutorial make a light that has this setup this is going to take a really long time to render [Music] [Music] my [Music] that is a different type of tutorial i just couldn't not make a tutorial about it so thanks for watching i was able to make this work in eevee as well let's have a look so now we are in the ev render engine the thing is that the shadow on the ground is going to look really weird look at this i mean this isn't what evie is really good at shadows so if we just focus on the volumetrics like the scatter part it actually works pretty good and the thing you have to do is that you have to make a ground plane with the texture and instead of it having an emission material you can see the emission shader has been swapped out with a transparent shader that is very important because then you're sort of just casting a shadow see like like that and that is basically what is happening in cycles as well but in eevee you can't really use nodes on the light so this is a nice workaround i think and there's one more important thing you have to do you have to select the object this plane that you make and under material properties make sure the shadow mode is set to either alpha clip or alpha hash i think it's alpha clipped set it like this this is almost a more intuitive way you can sort of understand how this works [Music] you

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Id: X9YmJ0zGWHw

Length: 9min 41sec (581 seconds)

Published: Wed Sep 01 2021