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While I was working on my over-30-FPS patch, I found out that the tower background in the credits scroll was being completely re-drawn every single frame, which was a bit wasteful and expensive. It's also harder to interpolate for my over-30-FPS patch. I'm guessing this constant re-draw was done because the math to get the surface scroll properly working is a bit subtle, but I've figured the precise math out! The first changes of this patch is just removing the unconditional `map.tdrawback = true;`, and having to set `map.scrolldir` everywhere to get the credits scrolling in the right direction but make sure the title screen doesn't start scrolling like a descending tower, too. After that, the first problem is that it looks like the ACTION press to speed up the credits scrolling doesn't speed up the background, too. No problem, just shove a `!game.press_action` check in `gamecompletelogic()`. However, this introduces a mini-problem, which is that NOW when you hold down ACTION, the background appears to be slowly getting out of sync with the credits text by a one-pixel-per-second difference. This is actually due to the fact that, as a result of me adding the conditional, `map.bscroll` is no longer always unconditionally getting set to 1, while `game.creditposition` IS always unconditionally getting decremented by 1. And when you hold down ACTION, `game.creditposition` gets decremented by 6. Thus, I need to set `map.bscroll` when holding down ACTION to be 7, which is 6 plus 1. Then we have another problem, which is that the incoming textures desync when you press ACTION, and when you release ACTION. They desync by precisely 6 pixels, which should be a familiar number. I (eventually) tracked this down to `map.bypos` being updated at the same time `map.bscroll` is, even though `map.bypos` should be updated a frame later AFTER updating `map.bscroll`. So I had to change the `map.bypos` update in `gamecompleteinput()` and `gamecompletelogic()` to be `map.bypos += map.bscroll;` and then place it before any `map.bscroll` update, thus ensuring that `map.bscroll` updates exactly one frame before `map.ypos` does. I had to move the `map.bypos += map.bscroll;` to be in `gamecompleteinput()`, because `gamecompleteinput()` comes first before `gamecompletelogic()` in the `main.cpp` game loop, otherwise the `map.bypos` update won't be delayed by one frame for when you press ACTION to make it go faster, and thus cause a desync when you press ACTION. Oh and then after that, I had to make the descending tower background draw a THIRD row of incoming tiles, otherwise you could see some black flickering at the bottom of the screen when you held down ACTION. All of this took me way too long to figure out, but now the credits scroll works perfectly while being more optimized. |
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This is the source code to VVVVVV, version 2.0+. For more context about this release, see the announcement on Terry's blog!
License
VVVVVV's source code is made available under a custom license. See LICENSE.md for more details.
In general, if you're interested in creating something that falls outside the license terms, get in touch with Terry and we'll talk about it!
Authors
- Created by Terry Cavanagh
- Room Names by Bennett Foddy
- Music by Magnus Pålsson
- Metal Soundtrack by FamilyJules
- 2.0 Update (C++ Port) by Simon Roth
- 2.2 Update (SDL2/PhysicsFS/Steamworks port) by Ethan Lee
- Beta Testing by Sam Kaplan and Pauli Kohberger
- Ending Picture by Pauli Kohberger
Versions
There are two versions of the VVVVVV source code available - the desktop version (based on the C++ port, and currently live on Steam), and the mobile version (based on a fork of the original flash source code, and currently live on iOS and Android).