Set Position With Custom Normal In Blender Geometry Nodes

Hey guys! Ever found yourself wrestling with geometry nodes, trying to achieve that perfect displacement effect based on custom normals? It can be a bit of a head-scratcher, especially when you're dealing with dense meshes from voxel remeshing and don't have the luxury of UV maps. Well, buckle up, because we're diving deep into the world of normals and displacements to unlock some cool techniques.

Understanding the Challenge

Custom normals are key when you need precise control over how your geometry deforms. Unlike the default normals, which are calculated based on the surface's orientation, custom normals let you define the direction of displacement. This is incredibly useful for creating intricate details and effects that wouldn't be possible otherwise. When working with voxel remeshed meshes, you often end up with a high-density mesh that lacks a natural UV map. This means traditional displacement methods relying on UV coordinates are out the window. That's where the magic of geometry nodes comes in. Geometry Nodes allows us to manipulate the position of vertices directly, using custom normals as a guide. The primary challenge lies in calculating these custom normals and then applying them to the mesh in a way that creates the desired displacement effect. This involves understanding vector math, attribute management, and the node-based workflow of Geometry Nodes. We need to figure out how to displace vertices along the direction of these custom normals, effectively pushing them outwards (or inwards) to create the desired shape. The beauty of this approach is its flexibility. You can define custom normals based on various factors, such as proximity to other objects, procedural patterns, or even image textures. This opens up a world of possibilities for creating unique and dynamic displacement effects. For instance, imagine creating a mesh that grows and pulsates based on a procedural noise pattern driving the custom normals. Or perhaps you want to simulate the effect of erosion by displacing the mesh along normals that are influenced by the flow of a virtual fluid. The possibilities are truly endless. This approach is especially useful when you want to create effects that are not easily achievable with traditional methods, such as sculpting or texture-based displacement. It gives you a fine-grained control over the deformation process, allowing you to create complex and organic shapes with ease.

Setting the Stage: Normals and Vectors

Before we jump into the node setup, let's talk normals and vectors. Think of a normal as an arrow sticking straight out of a surface. It tells us the direction the surface is facing. In Blender, normals are represented as vectors – a set of numbers that define a direction and magnitude in 3D space. In our case, we want to create our own normals, ones that aren't just based on the mesh's surface. This is where things get interesting. We can use various techniques to define these custom normals. For example, we might want to align the normals with the direction of a gradient, a procedural texture, or even the position of another object in the scene. The key is to calculate a vector for each point on the mesh that represents the desired normal direction. Once we have these custom normals, we can use them to displace the vertices of the mesh. The displacement is essentially a movement of the vertices along the normal direction. The amount of displacement can be controlled by a scalar value, which acts as a multiplier for the normal vector. This allows us to create varying degrees of displacement across the surface of the mesh. Understanding vectors is crucial for working with normals. Vectors can be added, subtracted, multiplied, and normalized. Normalizing a vector means making its length equal to 1, which is important for ensuring consistent displacement. If the normals have varying lengths, the displacement will be uneven, leading to unexpected results. Blender's Geometry Nodes provide a powerful set of tools for manipulating vectors. You can use nodes like Vector Math to perform arithmetic operations on vectors, and nodes like Normalize to normalize them. These tools make it easy to calculate custom normals and use them for displacement. The ability to manipulate vectors directly within Geometry Nodes is a game-changer for creating complex and procedural effects. It allows you to build systems that respond to various inputs and generate dynamic and intricate deformations.

Building the Geometry Nodes Setup

Alright, let's get our hands dirty with some nodes! First, fire up Blender and create a new object. This will be the base for our displacement experiment. Add a Geometry Nodes modifier to your object. This opens up the node editor, where the magic happens. Now, let's break down the setup step-by-step. We'll start by capturing the original position of our mesh. This is important because we'll be using this original position as a reference point for our displacement. Add a "Capture Attribute" node and connect it between the input geometry and the output. Set the attribute type to "Vector" and the domain to "Point". Plug the "Position" input into the "Value" input of the Capture Attribute node. This will store the original position of each vertex as an attribute. Next, we need to generate our custom normals. For this example, let's use a simple technique: aligning the normals with the direction of a procedural noise texture. Add a "Noise Texture" node and connect its "Color" output to a "Vector Math" node. Set the operation of the Vector Math node to "Normalize". This will normalize the color values from the noise texture, converting them into vectors that represent our custom normals. Now, we have our custom normals, but we need to apply them to the mesh. Add a "Set Position" node and connect it to the output geometry. This node allows us to directly manipulate the position of the vertices. Connect the "Position" input of the Set Position node to a "Vector Math" node. Set the operation of the Vector Math node to "Add". This will add our custom normals to the original position of the vertices, effectively displacing them. Connect the "Attribute" output of the Capture Attribute node to the first vector input of the Add Vector Math node. Connect the output of the Normalize Vector Math node to the second vector input of the Add Vector Math node. To control the amount of displacement, we need to scale the custom normals. Add another "Vector Math" node between the Normalize Vector Math node and the Add Vector Math node. Set the operation of this Vector Math node to "Scale". Connect the output of the Normalize Vector Math node to the vector input of the Scale Vector Math node. Add a "Value" node and connect it to the scalar input of the Scale Vector Math node. This Value node will control the strength of the displacement. Adjust the value to see the mesh deform. There you have it! A basic setup for displacing a mesh based on custom normals. You can now experiment with different noise textures, scaling values, and other parameters to create a variety of interesting effects.

Adding Directional Control

Now, the cool part! We want to displace in both directions along the normal – essentially pushing the surface both outwards and inwards. This creates a more pronounced and detailed displacement effect. To achieve this, we need to modify our node setup slightly. The key is to use a function that outputs both positive and negative values based on some input. A simple and effective function for this is the sine function. The sine function oscillates between -1 and 1, providing us with the directional control we need. Add a "Math" node and set its function to "Sine". Connect a "Value" node to the input of the Sine Math node. This Value node will control the frequency of the sine wave. Add another "Math" node and set its function to "Multiply". Connect the output of the Sine Math node to the first input of the Multiply Math node. Connect the Value node that controls the displacement strength to the second input of the Multiply Math node. Replace the Value node that was previously connected to the scalar input of the Scale Vector Math node with the output of the Multiply Math node. Now, the displacement will oscillate between outwards and inwards, creating a more complex deformation. You can adjust the frequency Value node to control the speed of the oscillation and the displacement strength Value node to control the overall magnitude of the effect. This technique is particularly useful for creating effects like ripples, waves, or pulsating surfaces. By combining the sine function with custom normals, you can achieve a wide range of dynamic and organic deformations. For example, you could use a 3D noise texture to drive the frequency of the sine wave, creating a more chaotic and unpredictable displacement pattern. Or you could use the distance from another object to control the amplitude of the sine wave, creating a proximity-based displacement effect. The possibilities are endless. The directional control provided by the sine function adds a new dimension to our displacement effect, allowing us to create more visually interesting and complex deformations. By mastering this technique, you can unlock a whole new level of control over your geometry and create stunning visual effects.

Optimizing for Dense Meshes

Dealing with dense meshes from voxel remeshing can be a performance hog, so let's optimize our setup. The key here is to minimize the calculations we're doing per vertex. One simple trick is to use a "Subdivision Surface" node with adaptive subdivision before the Geometry Nodes modifier. This can significantly reduce the number of vertices the geometry nodes need to process, while still maintaining a high level of detail in the final result. Another optimization technique is to use the "Attribute Statistic" node to calculate the average normal direction across a region of the mesh. This can be used to create a smoother and more consistent displacement, reducing the need for fine-grained control over each individual vertex. To implement this, add an "Attribute Statistic" node and connect it before the Set Position node. Set the attribute to the name of the attribute that stores our custom normals. Connect the "Average" output of the Attribute Statistic node to a "Vector Math" node. Set the operation of the Vector Math node to "Normalize". This will normalize the average normal vector. Use this normalized average normal vector instead of the individual custom normals for the displacement. This will create a smoother displacement effect, which can be particularly useful for large-scale deformations. In addition to these techniques, it's also important to be mindful of the complexity of your node setup. Avoid using overly complex calculations or excessive numbers of nodes. Simplify your setup as much as possible without sacrificing the desired effect. By combining these optimization techniques, you can significantly improve the performance of your Geometry Nodes setup when working with dense meshes. This will allow you to create more complex and detailed effects without running into performance issues. Remember, optimization is an iterative process. Experiment with different techniques and find the ones that work best for your specific project. By constantly seeking ways to improve the efficiency of your workflows, you can unlock the full potential of Geometry Nodes and create stunning visual effects.

Beyond the Basics: Advanced Techniques

Ready to take it up a notch? We can explore more advanced techniques for even greater control over our displacement. One powerful method is using field inputs to drive the displacement. Fields allow you to create complex patterns and variations in the displacement based on various factors, such as distance from other objects, procedural textures, or even custom curves. For example, you could use a proximity field to create a displacement effect that grows stronger as an object gets closer to the mesh. Or you could use a curve to define the shape of the displacement, creating organic and flowing deformations. To use field inputs, you need to connect a field node to the input of a node that supports fields. For example, the "Set Position" node has a field input for the "Offset" parameter. You can connect various field nodes to this input, such as "Proximity", "Curve", or "Noise Texture". Each field node will generate a field of values that can be used to drive the displacement. Another advanced technique is using custom attributes to control the displacement. Custom attributes allow you to store additional data on your mesh, which can then be used to drive various aspects of the Geometry Nodes setup. For example, you could create a custom attribute that represents the density of the mesh in different areas. You could then use this attribute to control the strength of the displacement, creating a more detailed and nuanced effect. To create custom attributes, you can use the "Attribute Create" node. This node allows you to create a new attribute and assign values to it based on various inputs. You can then use the "Attribute Sample" node to sample the values of the custom attribute and use them to drive the displacement. By mastering these advanced techniques, you can unlock a whole new level of control over your geometry and create stunning and dynamic visual effects. Fields and custom attributes are powerful tools that allow you to create complex and procedural deformations, pushing the boundaries of what's possible with Geometry Nodes. Experiment with these techniques and explore the endless possibilities they offer.

Conclusion

So there you have it! Setting position based on custom normals might seem daunting at first, but with the power of Geometry Nodes, it's totally achievable. We've covered the basics, explored directional control, optimized for dense meshes, and even dipped our toes into advanced techniques. Now it's your turn to experiment and create some amazing displacements! Go forth and node! Happy Blending!