Tracking pieces already on the board If you only have 1bit graphics that pretty simple isnt it?.. Your graphics and your game state are the same thing. When you detect a collision with already settled blocks you get OR the falling blocks bits into your existing state.. >making sure that rotation I wonder why hes bother to rotate (graphically) pieces in code when it would easier just to have the pieces rotated in the program data He says hes used one method over the other for speed.. >wont cause a collision with another piece again, that isnt hard.. somewhere in your struct for your pieces you have something that says how big it is, before you move a piece left/right or swap the piece out for a rotation you check that tetro_width + offset_x or go out-of-bounds, and looking for completed >lines all add up to one bid headache. so you have 16 entry long uint8 array.. you do some like this to check for complete lines. bool completelinedetector(){ for (i = 0; i < 16; i++){ if(checkarray[i] == 0xFF){ return true; } } return false; } if you count the complete lines you can write a routine to animate out the completed lines too.. "collision" detection is a case of comparing your incoming byte (a byte the represents the bottom of the current tetro shifted to it's current offset) with byte below the current y offset of the tetro in the check array learning how shifts, boolean logic work in your language of choice is a must. I do like hackaday.. but you guys really over hype stuff sometimes. Posted at 1:40 pm on Jun 20th, 2010 by cantido Excuse the typos etc. :P Posted at 1:51 pm on Jun 20th, 2010 by cantido

@cantido Yes, someone codes differently than you and people think thats neat therefore: HaD must over hype things up. /sarcasm The guy did it his own way, what are you complaining about? At least he bothered to do something, to reach out and learn; after all isnt that what hacking is about? To learn, share, and grow Posted at 2:05 pm on Jun 20th, 2010 by Comrade @Comrade >The guy did it his own way,.. I didnt say the guy was doing it wrong. Read this line from the hack a day text; >>ourselves we understand how difficult >>it is to explain how the program works. No, it isnt. If youve got more than a few bytes of memory to play with you dont even need to do bit shifting You can be very lazy and use your smallest native unit for each pixel! You have an 2 dimension array that has your game state and an array + x/y bounds descriptors for the pieces, the idea is to OR the pieces on to the game state array. You can do bounds checking by checking that the left edge of the piece isnt out of the screen and left edge + piece width + current offset isnt bigger than the screen when the user tries to move it left or right. Each time the piece moves down you compare the bottom of the piece array with what is below it in the state array, then you check the next line up,.. If there is a collision at any point the piece stops falling (I think the official rules include some grace time in which the player can adjust the piece). before the piece rotates you have to check the rotation will fit in the current state.. which is a just case of iterating over the state and piece arrays. When the piece has stopped falling you OR it into the state array. Then you check for complete lines.. which is (again!) just a case of iterating over the state array to find lines that are complete. There you go, Ive just explained this terribly complex piece of computer science for you. Use it wisely. The data structures and logic are all very simple. Which is why there are lots and lots of tetris-like games out there on everything from desktop computers to hacked printer firmwares. Posted at 2:53 pm on Jun 20th, 2010 by cantido cantido:

I agree. HackaDays summary makes Tetris sound impressive but it really isnt. I commend the guy for his efforts, but I have to be honest here weve all done tetris! I think it was about a decade ago that I threw together Javascript Tetris. It took me close to 6 hours to create from scratch (much of that just learning the javascript) this is with no former programming experience Tetris isnt that hard if you can think even slightly analytically But then again, maybe my perspective is biased? Since then Ive found everything including mario clones, 2D rendering engines, compiler frontends, and java servers to be challenging yet doable. I assumed HackaDay would be filled with more analytical engineer types than creative artists, but maybe Im wrong? There are a lot of very creative hacks and gadgets posted to this site many requiring extensive technical expertise but that says nothing about the editors. So maybe his rotation algorithm really isnt obvious to HaDs editors? Maybe it is really impressive to them? :/ Posted at 3:11 pm on Jun 20th, 2010 by BikeHelmet @Comrade oh and here is how you do rotation,.. notice that you dont actually need to do any complex maths; your struct looks something like this; 000: length 001: height 002: piece data .. 000 for nothing, 0xff for a . block or something like that. . If you can manage shifts etc you can use . bits for this *wowza!*, if you are using . tilemaps i.e have more than 1 bit graphics . you would have a tile number here and check . for anything that isnt 000 in your . checking routines. 008: pointer to next rotation (length depends on how big your pointers are) The last rotation points back to the original form. When the piece is rotated you dont need to do any rotation in ram.. you can find what you need using the pointer and because the last piece loops back to first you dont need any logic to wrap around.

You can use a table of pointers to the pieces and use a random offset to piece the starting piece + rotation (I think the official rules state that all pieces start at the initial form though.. so you would only put those into your table). On a micro you are likely to have lots of flash rom and very little data memory so use static data over generating stuff

in ram where ever you can.

Please feel free to use this highly sensitive data under the terms of the GPL documentation license.

Posted at 3:31 pm on Jun 20th, 2010 by cantido Pretty nice bit of project. See? Things dontt have to be sloppy. Posted at 4:28 pm on Jun 20th, 2010 by George Johnson The whole project emerged from neccessity for a good example in how to manipulate LEDs and draw 2D graphics, to help others learn. His solution may not have been the most elegant ever, and its certainly general in nature. But that was the point to provide a relatively easy to understand method for 2D rotation that works on a wide scale. He did it well. Its good that it was put on HaD, to maybe pique the interest of those new to embedded programming and/or 2D graphics. So, in summary: Criticizing the programming technique in an example for novices? Really? Posted at 7:05 pm on Jun 20th, 2010 by Roboguy As to the referenced article, I think its commendable to try to help those out who need it. I remember when I did Tetris (brand new to the language, to 2D graphics, and to programming in general). It was a great learning experience, but pretty tough. I think its great to walk people through the process and make it easier on them. Posted at 7:09 pm on Jun 20th, 2010 by Roboguy

I cant thank and respect this dude enough for not using a frickin arduino. Neat project. I need to get some displays so I can try graphics on PIC. Posted at 12:34 am on Jun 21st, 2010 by M4CGYV3R @Roboguy So, in summary, if you actually read what people write.. you would notice that I didnt criticise his code all that much. I criticised hack a day for saying this is hard to describe. Which it isnt. Its very simple. If I was going to criticise anything it might be the fact that hes used a massive micro when he really didnt need to. But thats probably just using whats at hand.. Posted at 2:05 am on Jun 21st, 2010 by cantido Leave a Reply Name (required) Mail (will not be published) (required) Website

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