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Two problems become none

No truism is always true, not even this one. I recently clashed with two common conceptions in software engineering: “All problems in computer science can be solved by another level of indirection.” – David Wheeler “Some people, when confronted with a problem, think ‘I know, I’ll use regular expressions.’ Now... Continue reading

Puzzle concepts

I’ve been doing more experimenting with the engine, trying to come up with a workable puzzle concept. Below are some videos and reasonings. First off, the game objective. Assuming that it’ll have something to do with the fluid, one possibility is that the player has to make the fluid flow... Continue reading

First gameplay

I had hoped that the editor would allow me to quickly test gameplay concepts by using “soft rules”: rules that are communicated to the tester verbally by me, instead of being enforced by the program. For example, I could say “Now try moving the orange ball into the blue rectangle,... Continue reading

Sandbox editor

To be able to test different configurations, I had a rudimentary text-based file format to describe levels in. It was fairly simple and easy to edit, but still, hand-typing coordinates is not my idea of fun. It was time to build a graphical editor. I plan to release the editor... Continue reading

The aspect ratio problem

In the days of MS-DOS, things were simple. If you developed a game, you usually wrote it for one specific VGA or SVGA resolution, such as 320x200 or 640x480. If someone’s video card did not support this resolution: tough luck. Nowadays, there is such a variety of screen resolutions that... Continue reading

Stam solver working

This week I worked hard on getting the fluid solver in the style of Jos Stam working. The basics were easy enough, but Stam makes some simplifying assumptions, so the continuation was not quite trivial. But combined with what I learned in my earlier work on the free-surface simulator, I... Continue reading

New approach

From my previous posts, it must now be clear that free-surface fluid dynamics is hard. This is mainly caused by the free surface. Without that, it is possible to write a fluid-in-a-box in a little over 100 lines of C code, as Jos Stam did in his paper Real-Time Fluid... Continue reading

Fluid solver on the GPU

Work on this project has been standing still for some time while I was working on another project. But this week I picked up work where I left off: making the fluid simulation even faster. Since the SOR solver I was using lends itself well to parallelization, and video cards... Continue reading

Optimization story

The fluid simulation was beginning to approach results of decent quality. However, it was still far too slow. Most of the screenshots I’ve shown so far were done on a 64x64 grid, which barely ran in real-time even on my fast Intel i7 machine. For a full-screen game, I’d need... Continue reading

The joy of graphical debugging

I’m a very visual type of guy. A picture really does say more than a thousand words. It should come as no surprise that my way of coding and debugging reflects this. How does one debug a fluid solver? It is possible to step through the code, but that does... Continue reading

Fluid still failing

It’s been a busy week with little to show for it. As I wrote last time, I more or less gave up on the SPH particle-based method, and opted to fix my grid method instead. That turned out to be harder than I expected. As a first attempt, I tried... Continue reading


To find the source of the instabilities, I pulled my code apart into more independent steps, that could individually be turned on or off. This did result in a speed hit, but allowed me to quickly trace the source of the problems to the advection routine. This is the part... Continue reading

Lid driven cavity

Since no existing code fit my requirements, I started working on my own fluid simulator a few weeks ago. The idea was to try both a grid-based and a particle-based method, and see which worked better for my situation. I started with the grid-based version. My code was not based... Continue reading

Previous work

I looked around for existing code or libraries to do the fluid simulation for me. There are some, but most are either GPL-licensed or too expensive, so they are out of the question for a small-time independent developer like me. Some publications exist on the topic, most notably Jos Stam’s... Continue reading

The beginning

Today, I’m really getting started. I quit my job last Friday so that I can work on this project full-time. I have some financial reserves to keep me alive during the period of development. Development of what? That is still largely an open question. I know it will be a... Continue reading

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