Documentation / Node reference / code nodes
How much the pixel this tex/Builder is writing differs from the average of the pixels around it.
Texture
Connect a texture, from a code/TextureInput (a picture wired into the tex/Builder) or a code/Param set to NodePath, and this node gives its Laplacian at the pixel being written: the average of the pixels around it, minus the pixel itself. It is 0 where the texture is flat, positive in a dip, negative on a bump. It reads all four channels at once and returns the four Laplacians.
This is what makes things spread out. Add a little of it to a picture, step after step in a tex/Solver, and the picture diffuses: a blur by steps, heat flowing, the two chemicals of a reaction-diffusion spreading before they react.
kernel says which pixels around it are averaged. On a 2D picture, FIVE_POINT takes the four side pixels, and NINE_POINT the eight around it, the corners weighed less: rounder spreading, for four more reads. On a 3D texture, in a 3D tex/Builder, SEVEN_POINT takes the six voxels that share a face, and TWENTY_SEVEN_POINT all 26 around it: smoother, for 20 more reads. A kernel for the other dimension than the texture's stops the build with a message saying which kernels to choose. ROUND and FAST follow the texture: ROUND is NINE_POINT on a picture and TWENTY_SEVEN_POINT on a 3D texture, FAST is FIVE_POINT and SEVEN_POINT, so one graph runs on either. A 2D picture in a 3D builder is read at the voxel's x and y, with a 2D kernel.
borderMode says what is read past the edge of the texture, on each axis, as in code/TextureTexel. REPEAT, the opposite side, is what a simulation on a tile needs.
The kernel input takes the kernel as a number, from a code/Param or a code/Constant of type UInt32, holding one of the kernel values (FIVE_POINT 0, NINE_POINT 1, SEVEN_POINT 2, TWENTY_SEVEN_POINT 3, ROUND 4, FAST 5). A code/Param changes it without rebuilding the shader. Wired, it follows the texture: FIVE_POINT, SEVEN_POINT and FAST read the side pixels or face voxels, any other value the round kernel of the texture's dimension.
| Name | Type | What it does |
|---|---|---|
| kernel | UInt8 FIVE_POINT · NINE_POINT · SEVEN_POINT · TWENTY_SEVEN_POINT · ROUND · FAST | Which neighbours are averaged, when nothing is wired into the kernel input. For a 2D picture: FIVE_POINT, the four side pixels (1/4 each), or NINE_POINT, the eight around it (sides 0.2, corners 0.05), rounder for four more reads. For a 3D texture: SEVEN_POINT, the six face neighbours (1/6 each), or TWENTY_SEVEN_POINT, all 26 around it (1/26 each), smoother for 20 more reads. A kernel for the other dimension stops the build with a message. ROUND (NINE_POINT or TWENTY_SEVEN_POINT) and FAST (FIVE_POINT or SEVEN_POINT) pick by the texture's dimension, for a graph meant for both. |
| borderMode | UInt8 CLAMP · TRANSPARENT · REPEAT · MIRROR | What is read past the edge of the texture. CLAMP: the edge pixels repeat. TRANSPARENT: transparent black. REPEAT: the opposite side of the texture, for a picture that tiles, as a simulation on a tile needs. MIRROR: the picture flipped at its edge. |
Scenes you can open in the editor that teach this node.
The tex/ReactionDiffusion node grows a pattern from a star seeded in a picture: two chemicals spread and react, and the star becomes a maze of stripes. Other values of F and k give coral, worms, spots and holes.
tex/PolyNode tex/Solver tex/Builder code/TextureLaplacian
The tex/ReactionDiffusion node grows a pattern in a 64 by 64 by 64 texture: two chemicals spread through the volume and react, and three seeded spheres grow into a maze of folded sheets. The viewer draws them as fog with a mat/Volume, and beside it as a solid with a mat/VolumeSurface, both reading the texture where the GPU wrote it. Open the texture panel to see it slice by slice or raymarched.
tex/PolyNode tex/Solver tex/Builder code/TextureLaplacian mat/Volume mat/VolumeSurface
This page is generated from the engine, so it describes the release you can download. The same text is in the editor's Help panel next to the node itself.