I've been quiet on my game for a week (except for discussing a shader I made for it) but I've still been busy, on two main things. One is a graphical overhaul, involving the shader but also a new way of drawing filled rings and a lot of tweaks to make it work, which I finished last week.

## Monday, 23 April 2012

## Thursday, 19 April 2012

### Pixel Bender bug

The circular gradient fill shader I wrote yesterday took more time than expected as for a while it would not work: more specifically it worked fine in Pixel Bender Toolkit but not in Flash. And it failed in a particular way: on use it would instantly lock up rather than fail with an error or produce the wrong result.

## Wednesday, 18 April 2012

### Circular gradient shader

This is something I started coding today before I realised it wasn't available in the BitmapData APIs: the gradient fill available comes in two varieties, linear and radial. But the latter is always based on the distance from the centre, never the bearing from the centre as I wanted. So I wrote a shader for it, to generate a result like this:

## Thursday, 12 April 2012

### Quaternion rotation shader

After writing yesterday's post I wondered how easy it would be to use the mathematics in a shader. This would be a natural way to extend my cross product shader, replacing the simple product in that with a more general geometric product.

### Multiplying two vectors

In mathematics there are a number of ways to multiply two vectors. The most common is the dot product, which works for any two vectors of the same size. In three dimensions there's the cross product, while in two dimensions there's the perp dot product, sort of equivalent to the cross product.

But they all have the weakness that they are not invertible. Given the cross product

and knowing

**c**and another vector it isn't possible to calculate the third vector (**c**×**c**= 0, so given a solution all points on a line through this solution parallel to**c**are also solutions).## Sunday, 8 April 2012

### Oops

I've been working on the front end, which also means I've been deciding how many levels, what distinguishes them etc. It's very different from Bug Tunnel Defense where every level was designed individually. Here the levels are mostly numbers. But at the same time I've been changing and adding things to make it easier to introduce elements progressively, and make for a more varied experience.

While testing some of these changes I generated the above screenshot, which is a really bad way to start a game (hence the title), but is also more aesthetically pleasing than the usual cluttered mess of the screenshots the game produces. It shows off some elements of the game much more clearly than usual, although they really need to be seen in motion to appreciate.

## Friday, 6 April 2012

### Shader vs. ActionScript revisited

Last week I created a shader based on the cross product. This was a simple experiment, done mostly as it was very straightforward: the shader code has only three lines of simple vector maths. But since I realised that it should be possible to recreate it using ActionScript, in particular using a ColorMatrixFilter.

## Wednesday, 4 April 2012

### Five new screenshots

It's two weeks since I lasted posted any screenshots. Lots of changes since then, most of them graphical. All of the core gameplay is in now, although much needs to be done, not least a front-end.

## Monday, 2 April 2012

### 100th post

According to Blogger I've written ninety-nine posts to date, making this the one-hundredth, a good point to look back and review my progress so far. All of the lists are in date order. These are based on the tags but not exactly so, and there's some overlap with some posts linked more than once, so they don't add up to ninety-nine.

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