To add variations to each light instance, beyond the standard instance/copy attributes, we use the** instancepoint()expression. By turning on Active Radius, and reducing the distance to just beyond the natural falloff of your light, you can help speed up renders a fair bit.
There is an optimziation on lights to tell Mantra when to consider a light for contributions. An instance object instancing lights won’t show up in the light lists, just the object ones, but the lights will stil work fine. Because we are changing lights, which need to go into the IFD, we have to use Full Instancing (Fast Instancing is for render-time changes).ĭon’t forget to hide/turn off the original light in your scene! You can also exclude the light from the Objects list on your Mantra ROP. The second important point (ha!) is to use Full point instancing, and not the Fast type. Just remember to move the display/render flag from the Add SOP which is on by default, so that your points are used by the instances. Inside, you can either generate your points, or more likely merge them from another object. To instance a light across points, you can use an Instance Object. This is a simple demonstration of how to instance lights, and how to read attributes from the points onto each light instance. Instancing lights for Mantra has had some excellent optimizations in Houdini 16, specifically since build 537.
