Friday, 18 March 2016

Uneven Curved Corners

I was surprised how well a simple technique worked to get a curved corner that had a different radius in two directions.

To get the first curve I subdivided a plane and moved the vertices to line up with a circle in each of the directions I wanted the corner.

To get the curve round the corner to be a larger curve than the others I added a circle and simply scaled each row of vertices in just one direction until the edge vertex lined up with the view of the edge of the circle.

The other vertices scaled neatly to keep a smooth complex curve. In the above example I scaled [S] and restricted it to the Y axis [Y] which is the direction of the green arrow in the above image.

It was the fact of scaling rather than moving that kept the curve in the other direction looking smooth.
I started from the top and always scaled to the centre line of the guide circle. I just selected the upper most vertex as the last selection and scaled towards that.

It's much harder to describe than it was to do.

Thursday, 10 March 2016

Modelling with quads

I've been working on some static models of cars. This hopefully this will improve my 3D modelling skills.

I am trying to stick to the pretty much universally recommended way of doing this and that is to use only quads. Not triangles.

There are several articles online about why quads work better. Here's a link to just one explanation but a quick search on Google will find you lots of others. In short, quads can be smoothed, quads maintain edge loops and can be subdivided for improved quality results.

Most balance articles also mention that there are cases for using triangles in some parts of the model but they should be hidden out of sight. I now know why I found it so difficult to get smooth faces on some of my earlier models. I'd used triangles in the wrong places.

From a games perspective, most, if not all rendering is done as triangles but we are talking about the best way to create the model. Quads, apparently also animate better because the folds will be more predictable.

Anyway. The point of this post is to remind myself of how I have made some shapes with quads, avoiding triangles.

At the moment there is just one tip but I'll add more as I work them out.

  • Reduce the number of edges subdividing rectangles 

This transitions from a row of three quads down to a row made with just a single quad. A complex shape at the bottom of the face and simplified at the top.

I often end up with this situation when creating curves within otherwise flat faces.

Another example, 10 quads down to just two.

Other useful articles and tips:
What shape should the quads be? Evenly sizes or any shape.
Also look for edge-parallel mode. After pressing Ctrl-R for a loop cut, press E to align to an edge and F to toggle between which edge to align to.