Currently...

Well now that I've got a half decent framework up a running I've just started to build a test project. Nothing special, just a simple match 3 game to make sure the framework is useable. So far so good. I'll post a link to the finished project once I'm done. Hopefully won't take long. Famous last words.

The other thing

While working on my sprite editor I've also been working on a more consistent framework for my projects. Whereas my previous isometric engine utilised OpenGL, it was kind of thrown together with little thought for what was where with the best intentions of sorting it out later. Instead of going through the laborious process of untangling a big mess of code I decided to start from scratch and, armed with the knowledge garnered from writing my isometric engine, I was able to decide on what was needed and what was completely unnecessary. With the new framework I've separated all aspects of the basic structure into clearly defined units.

I have a utilities unit which contains the main Game class. The game class is used for storing common objects that all games would contain;

log file (Class)
quit flag
title
framerate timer (Class)
pause flag

The Utils unit also houses some commonly used functions. All subsequent units have access to the Utils unit.

The Graphics unit houses the Screen class and the Sprite and SpriteManager classes. This is the only place where direct OpenGL calls should be made.

The Input unit is used for interfacing with the mouse and keyboard. I am using SDL for input but all SDL calls are contained here and there is no reason to directly call SDL outside of this unit.

Here's a screenshot of a very simple program written to test the framework. It is approx 200 lines of code in the main program since most of the work is done behind the scenes in the framework or encoded into the sprites using my sprite editor.


(Oh yeah, I borrowed the sprites from the Internets)
Download it here.
Use arrow keys to move one of the guys and be sure to click and hold for flames galore.

My sprite editor

Since my last post I've been creating a sprite editor which allows me to load a sprite sheet and section it off into frames. I can then also anchor points so that animations are drawn smoothly and trigger frames so that when I use the animation in the game I can look out for these triggers and generate an event based on the trigger value. For instance a zero would be a null trigger since the default for all frames is a zero. However a trigger value of one might be the shoot trigger. In which case I could generate bullets whenever this trigger frame is drawn. Instead of having the bullets generated at the beginning of the shoot animation I could have them generated at the exact frame where the gun recoils. Another example would be the jump animation. Let's say we've got a Prince Of Persia-esque character walking along then the player hits the jump button and this begins the jump animation. Now in this version there's a few frames of pre jump action where the character compresses his body then explodes into the jump. It would seem a bit odd to have the character jumping the instant this animation starts so instead I add a trigger frame at frame 4 and the animation is much more convincing. Now this could all be hard coded but the problem with hard coding things like this is that it's much more effort and should the need arise to change the animation then the code would need editing and recompiling, also the code tends to look like crap when there's special case stuff like that dotted all over the place.

Boring boring tools

After working on the isometric engine for so long and hitting countless dead ends and brick walls I'm currently taking a break from all that by building some tools for use with the engine. I'm currently working on my sprite editor which will allow me to import a bitmap image, split it into frames, add anchor points to each frame and then save it in my hand rolled sprite format. Alongside that I'm just learning a bit more about OpenGL vertex arrays and seeing if I can utilise them to increase my ever dwindling framerate. Did check out display list but they seem unsuitable what I'm doing not only because they are now deprecated and probably won't be supported at all much longer but also because they only seem to be useful for static stuff. Might be handy for a UI overlay but aside from that I can't find much good for them. I'll try and post a bit more from now on too.

A minor victory

Apologies for the delay between posts. Had to move flat and so programming took a bit of a backseat. After trying to squash the draw error using various methods I've finally made some progress using masking. I can now redraw the entire area occupied by a sprite correctly with any overlapping objects drawn either behind or in front without any issues. As a result I can also implement a dirty rect system for redrawing objects. The plan is to create a grid of rectangle. When anything moves a flag is switched on the relevant grid locations and all objects that are within those sections are redrawn. Should save a lot of time when it comes to drawing any scene. Current concerns lie with scrolling. If the user scrolls the scene then everything will need redrawing and since the camera will probably lock onto the player this means full redraw with every movement. I'm sure there's a way of shifting the colour buffer so that the OpenGL moves the ready drawn scene and the only redraw will be things coming into view. Right now I've got other stuff to worry about.

Can't talk now. Moving

Just finished moving hence there's a distinct lack of updates or programming of any kind going on right now. Hopefully get some work done tomorrow, will update ASAP.

OpenGL is here

Finally got round to porting across to OpenGL. It's so much faster. With the same number of objects (78) and no optimisation (i.e all objects redrawn every frame) I'm getting 1300 frames per second in windowed mode, compared to 50fps when using Windows GDI. That's a nice healthy number since my target is 60fps. Still got some bits to do and my textout function seems to take a huge chunk out of the framerate so it runs a lot slower when in debug mode with all sorts of data on screen. Although 1800 won't be the final framerate since I'm expecting to have hundreds of objects on screen at the same time so this will obviously slow things down but it does mean I've got a lot of room to play. Once I've got it running properly with that many objects I'll start adding the selective redraw stuff and maybe double linked lists to speed up the sorting algorithm. My friendly host JDarling from EonClash has given me some pointers on linked lists so I'll be reading up on that soon enough. I'll post some screens and a new download very soon.