For my next modelling challenge I chose this Nerf gun which has a number of topology challenges. Initially I tried using some snaps from my iPhone. Having various profiles makes precise modelling much easier but the problem with these images is the perspective, which messes up the scale. It would be possible to flatten out the perspective somewhat using a telephoto lens but I decided to ditch the top and front profiles and use the side profile as a rough guide together with measurements from the actual, physical gun, which I have.
I started with the gun cylinder using a Cylinder Object. The initial cylinder (left) didn’t have enough edges to allow for sharpening the cuts needed for the recesses, so I ended up going with 64 edges (right). These extra edges also ensure that when the barrels were in place (added using a Mograph Cloner in Radial mode) the edges where the objects intersect lined up fairly closely.
Rather than cut into the geometry for each barrel, I chose one barrel, selected enough loops to leave tow on each side of the barrel (totalling 11 loops) and deleted all of the other geometry.
This was then duplicated using a Mograph Cloner object in Radial mode. It resulted in a slight overlap since the original edge count was 64 and the total edge count after cloning was 66 (6 x 11). This resulted in a slight geometry overlap but dropping everything into a Connect object dealt with that issue, and having the higher edge count up front meant the slight discrepancy in the spacing of the loops on the cylinder made no perceptible change to the circular shape. I tried to get the edge count exact up front so I wouldn’t have to deal with any of these issues but I couldn’t get the math right and have the barrels be the correct radius.
After adding an edge loop around the recess and sharpening cuts, the result under subdivision was nice and clean.
The next section to tackle was the barrels which have two parts – the black, outer section and the orange inner section. To treat these as separate objects I split off the front section of one of the barrels and added it into a new Mograph Cloner in radial mode.
The next step was to connect the barrels to the front part of the cylinder, which was split off the main cylinder section. To do that I used Connect & Delete to combine the front of the barrels with the front of the cylinder and the Bridge tool to add in the connecting geometry.
I used the Bevel tool in Solid mode to add sharpening cuts and the result under subdivision looks pretty smooth.
Cutting details into the cylinder is fairly straight forward as this is still inside a Cloner object and here I used the Slide tool to clone extra edges. Starting with enough edges in the cylinder allowed me to cut in this kind of detail and not effect the overall curvature.
The trickier part is sharpening the detail under subdivision and this take practice. Here I used a looping system to create the sharpening without messing with the cylinder curvature. The result is all quads and smooths cleanly under subdivision.
Here’s a more simplified example from Serge Step. Notice how this does add an extra loop cut across the model which was okay in this situation but may not be an option in other situations. The kind of sharpening solution you choose depends on your topology.
A few more simple loops to finish this detail. Simple loops such as these avoid propagating cuts across other sections of the model, which might mess with curvature or cause issues later down the line.
This detail at the back of the cylinder started out as a Cylinder object. Cloning a small section using the MoGraph Cloner object in Radial mode obviously saves a lot of tedious work.
The completed cylinder and barrel section.
Starting on the handle with big polygons to rough out the basic shape using the Poly Pen tool.
Establishing the topology in 2D before adding depth is a good way to work on these kinds of models.
Once the base topology is in place the next step is to extrude and drop into a Symmetry object.
Detail starting to emerge after a few control cuts and extrusions, smoothed inside a Subdivision Surface object.
Added a booled capsule section to retopo onto using the Poly Pen tool in conjunction with the Shrink Wrap deformer. In the image below I’ve shifted the boole geometry to the side for comparison with the new geometry. Note how I had to split the surrounding geometry off of the main geometry in order to get good results with the Shrink Wrap deformer.
Once the new geometry was complete it was collapsed then welded back into place onto the main geometry.
This example shows the n-gons created by adding sharpening cuts to two opposing concave corners, and the all quad solution using a single diagonal cut.
Here’s another sharpening solution using all quad polygons.
Although the main body of the Nerf gun is a single object, the plastic has insets that make it appear to be constructed of more than one section. Rather than recreate the faux detail I decided to split the model into the actual sections. This had the added benefit of making it easier to sharpen the sections individually rather than as a single object.
Sharpening the trigger section required extra loop cuts which took a little time to resolve but resulted in a pretty clean mesh.
The trigger was once again modelled flat then extruded.
The slide started off as a cube…
A challenging section to sharpen with four close corners next to a curved section, which holds up pretty well up close.
The site was created by adding cuts into the main gun section, extruding and working in symmetry of course!
The front hinge started as a cylinder.
The completed front hinge.
adding a tooth into this section required some creative looping to sharpen and not affect the surrounding curvature.
The front and back hinges complete, allowing the cylinder to rotate out for bullet loading.
Getting the initial flat topology right up front made adding the extra grip detail straight forward.
The butt of the grip was surprisingly challenging at first but once I again working flat to establish the initial shape made it easier.
To create this section of the sight I booled in a cylinder object and cleaned up. If I had used more side in the cylinder I would have less pinching at the join but that would have given me more geometry to have to clean up. It’s generally a trade off in these situations and because we won’t be that close to the gun I decided to start with less cylinder sides.
The finished sight under subdivision.
Adding in these kinds of details under subdivision with curved sections requires creative sharpening solutions, as any extra edges would have messed up the curvature.
The main section of the gun is the most detailed single piece of geometry I’ve sub-d modelled to date. I ended up with only two triangles and no n-gons.
I threw some Cinema 4D materials onto the finished model. Those materials will become the different layer sets within Substance Painter.
Unwrapping the UVs in 3D Coat took a couple of hours. As I was unwrapping I discovered small topology problems (mostly caused by points being welded after optimization) so had to go back to Cinema 4D a few times, make the corrections and re-export.
In Substance Painter I decided to create the look of a actual weapon but with Nerf colours. The new Anchor Point system helps to create the pealed paint.
Here are the final renders.