BlendLuxCore Quick Start Guide

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Revision as of 09:22, 5 May 2019 by Byob (talk | contribs) (Todo)
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Switching to LuxCore

After you have installed the addon, switch the render engine in the info panel on the top to "LuxCore".

Switch to luxcore.png

If you now press F12 or hit the render or animation buttons, the BlendLuxCore addon will create a LuxCore session and convert the Blender objects, camera, lights etc. to a LuxCore scene and start to render it. Note that addons like this one were called "exporters" in the past, however BlendLuxCore by default does not export any files to the harddisk, so it's probably more appropriate to call it an "integration addon" for LuxCore or something like that. (It's still possible to write the LuxCore scene to disk, though - can be handy for network rendering)

Just press F12

Now, if you loaded one of your old scenes or created a testscene with some cubes on a plane and a monkey head and you press F12, the result will probably look a bit like this:

This is Piita's Hungry for Light scene from the old LuxRender show-off pack

Which raises several questions:

  • Why is everything covered in checkers?
    In BlendLuxCore, every material should have an associated node tree. We did not touch any materials yet, so they are converted with the fallback material that is supposed to tell you "this object is missing a material (or node tree)". More on materials later.
  • Why is the render not stopping and the progress bar not filling?
    By default, LuxCore renders endlessly until you press Esc to stop the render (when you are satisfied with the noise level). You can specify halt conditions to tell LuxCore to stop rendering after a certain amount of time, samples or noise level is reached, but this is only strictly required when you want to render an animation or multiple render layers (otherwise the first frame or the first render layer would render endlessly).
  • Why is everything slightly blue?
    Because the world in BlendLuxCore is set to a "Sky" light by default. The world light source can be changed in the world panel.

Materials

A quick tour of material settings:

  • Select an object.
  • Open the material tab in the properties:
    Props material.png
  • You will now see a button called "Use Material Nodes". If you would click that, it would add a matte material (similar to Cycles' "diffuse" shader).
  • However, you can also click one of the buttons in the panel below that is labeled "Node Tree Presets". It offers several of the base materials with only one click. Here is a description of the materials with example images: LuxCoreRender Materials
  • After you clicked one of the buttons, open a node editor. It will be showing the wrong kind of node tree (probably compositing nodes), so switch the node tree type in the header to "LuxCore Material Nodes", as seen here: BlendLuxCore Node Editor
  • If you still do not see any nodes, try to zoom out and pan around a bit or press the Home key on the keyboard. BlendLuxCore adds nodes around the origin of the node editor, and your focus might be set somewhere else from before.
  • After you found the nodes, try adding a few more materials. Start a viewport render and connect them to the output (or duplicate the output and switch between them) to see how they look like.
  • Note that in LuxCore, all materials have three sockets in common:
    • Opacity: Used to make the material transparent. In LuxCore this is usually preferable to using the classic "mix with transparent shader" approach because the opacity socket is optimized and much faster. So if you want to make leaves with an alpha texture, plug it into the opacity socket of a glossy translucent material.
    • Bump: Used for bump or normal mapping. If you have a normal map texture, create an imagemap node, select the texture and enable the "normalmap" checkbox on the imagemap node. The output will then automatically change to the "Bump" type and you can plug it into the corresponding material socket. In the "Utils" node category there is also a "Bump" node that can be used for classic greyscale bump maps.
    • Emission: Any material can emit light. Click the "Add" button next to the Emission socket to configure light emission.


Lighting

Start from a new file in Blender. Depending on your start-up file you might already have a light in your scene. Press F12 to render. If you get an error about no lights in the scene then simply add an area light (Shift A->Lamp->Area) and press F12.

Lighting a scene is usually done by area lights or a HDRI. Go to the World panel and enable the HDRI option and open a HDRI file. Render. On this panel you can also enable/disable the default sky lighting.

Blendluxcore world panel.png


If your start-up file in Blender has the sun lamp, you might not see the HDRI light up your scene now because the sun lamp overpowers the HDRI. Stop the render (ESC) and enable viewport rendering (Shift Z). Select the sun lamp and decrease its Gain until you can see the HDRI lighting. You probably need to use a low gain(0.00001) as the sun lamp is very bright.

Blendluxcore sun object data panel.png

For more in-depth information about lights, see

Texturing

Add a Glossy material node (Shift A->Material->Glossy) and connect the material socket to the material socket on the output node. Open a texture in the image editor or drag and drop it into the editor. In the node editor add a texture node (Shift A->Texture->Image) and select the texture in the node. Connect the color socket from the texture node to the diffuse socket on the material node. If you have a roughness/specularity texture and a normal map texture you can add those too in a similar way. Drop the two textures into the image editor and duplicate the texture node (Shift D) two times. Select the roughness/specularity texture in the second texture node and connect its color socket to the roughness socket on the Glossy node. Select the normal map in the third texture node, enable the normal map option and connect the node to the bump socket on the Glossy node. Render.

Node setup and finished render


Camera

Auto Brightness

The camera will adjust the brightness automatically by default but you can disable it here if you need more control. If you are using a very bright lamp such as the sun along with weaker lamps such as area lights or HDRI's, the weaker lamps can look like they are not emitting any light, but in fact they are over-powered by the sun lamp. If you disable Auto Brightness you will need to adjust the brightness of all lamps individually.

Blendluxcore camera panel.jpg


Depth of Field

Enabling depth of field will render out of focus objects blurry. You get most control over this by placing an Empty in your scene and selecting that Empty as camera focus. You control the blurriness with the F-stop value. This works in the same way as a real camera: a low value (about 1) gives a more blurry/out of focus render. Increase to get a more in focus effect.

Depth of field (left) and no depth of field (right)


Render Settings

Render Engine

Path + Sobol is the fastest and works good for scenes with simple lighting such as studios, well lit indoors and outdoors. Bidir + Metropolis can handle anything that Path + Sobol can and it can also render scenes with more difficult lighting such as light coming in from outside a room. Bidir + Metropolis is also required if you want to render caustics.

For more in-depth information about the render settings, see BlendLuxCore_RenderPanel.

Blendluxcore render engine.jpg

Halt Conditions

By default the render will stop only when you stop it. Here you can set specific conditions when you want the render to stop.

Viewport Settings

If you need the viewport render to run longer than the default 10 seconds you can change that here.

Blendluxcore render halt.jpg


Questions

If you are a beginner and have a question that's not covered by this guide yet, send a PM to "B.Y.O.B." or "Piita" in the forum.

You are also welcome to ask any questions in our user support forum or discord.