Could this work?

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Could this work?

symaxian 29 Sep 2007 05:24

I was wondering if there is any truth at all to this loop being used to load a background of sprites.
Is it coded right, impossible, is there an easier way, is it impractical, or is it revolution of TI-Basic please tell.

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:16->Y
:Lbl 1
:For(X,1,16
:If L1(X+Y)=1
--------(X*5)x((Y/16)*7) Pt-on commands for grass
:If L1(X+Y)=2
--------(X*5)x((Y/16)*7) Pt-on commands for water
:If L1(X+Y)=3
--------(X*5)x((Y/16)*7) Pt-on commands for mountains
:End
:Y+16->Y
:Goto 1

---

I didnt feel like writing the Pt-on commands but I hope you get the idea.
I used 5*7 sprites for the ease of the 16*8.
Im not real worried about the speed of loading the sprites, unless its ungodly long.

Last edited on 29 Sep 2007 05:25 by symaxian Show more

Re: Could this work?

burr 29 Sep 2007 05:51

I'm not completely sure I understood your question, but I'll try my best to answer it. If you have any additional related questions, just ask.

The most common method used for displaying multiple rows of data or graphics is by using two nested For( loops. For example, a matrix is commonly used to store the data of the game board, where you assign a value to each type of piece on the board: an empty spot is typically 0, the player might be 1, and a wall would be 2. When displaying the game board on the screen, you would then use the two For( loops method:

:[[1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]
[1,0,0,0,0,0,0,1,2,1,0,1,0,1,0,1]
[1,1,1,1,1,0,0,1,0,1,0,0,0,2,0,1]
[1,2,0,0,1,1,0,0,0,0,0,1,0,0,0,1]
[1,1,1,0,1,0,0,2,1,1,0,1,0,1,0,0]
[0,0,0,0,1,0,1,0,1,1,1,1,1,1,0,1]
[1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,1]
[1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
:For(X,1,16
:For(Y,1,8
:Output(Y,X,sub(" XO",1+Ans(Y,X),1
:End:End

Re: Could this work?

burr 29 Sep 2007 06:30

If you are looking for more information, I suggest you read The Complete TI-83 Basic Optimization Guide by Arthur O'Dwyer. Among other things, he covers graphics quite intensively.

Re: Could this work?

symaxian 29 Sep 2007 06:43

Sorry I guess I didnt word my question well.
Would this code be practical for generating a map of multiple 5*7 sprites made out of Pxl-on commands.
Ive broken it down in sections and little notes.

---

:1->Y
:Lbl 1
:For(X,1,16

:If L1(X+Y*16)=1
\Checks if the list value for the next space is a sprite for grass
\Then generates the grass sprite from simple Pxl-on commands
-—-(X*5)x(Y*7) Pxl-on commands for grass

:If L1(X+Y*16)=2
\Checks if the list value for the next space is a sprite for water
\Then generates the water sprite from simple Pxl-on commands
-—-(X*5)x(Y*7) Pxl-on commands for water

:If L1(X+Y*16)=3
\Checks if the list value for the next space is a sprite for mountains
\Then generates the mountain sprite from simple Pxl-on commands
-—-(X*5)x(Y*7) Pxl-on commands for mountains

:End

\Checks if this is the last row has been displayed then goes to Lbl 2
:If Y=16
:Goto 2

\When the current row is done displaying it increases the Y
coordinate by 1 and starts the loop again.
:Y+1->Y
:Goto 1

:Lbl 2

---

:If L1(X+Y*16)=1
\The X+Y*16 argument is the entry of the 5*7 space in the list, the list value determines the sprite shown. Y*16 because theres 16 columns, so the rows read right to left then the next row just the same as written text. 1x1 of 16x8 would be entry 1 of the list, 16x8 of 16x8 would be the last entry in the list, 128.

---

-—-(X*5)x(Y*7) Pxl-on commands for water
I didnt feel like writing out every Pxl-on command for the sprite so I placed these. So basically if you use 35 Pxl-on commands, one for each pixel in the 5x7 sprite, you would get the whole space filled black.

---

I thought of this as a possible way to make a whole screen from sprites without Assembly or Specific Text Sprites, and with the matrix it seemed as though you needed a different matrix for every different character/sprite.

Re: Could this work?

burr 29 Sep 2007 07:19

I understand you now. Thanks for the follow up :) That method works just as well as any other, but whether it is practical is up to you. However, there are a few things you can do to make the code run faster:

• Replace the Goto/Lbl's with a For( loop. A For( loop is not only easier to read, but is also faster as well.
• Place the sprite code in a separate subprogram, and then just call the subprogram with the appropriate value (i.e., If 2=L1(X+16Y is true, then you would pass 2 to the subprogram, and display the water sprite).
• Replace some of the Pxl-On( commands with text (i.e., a text-sprite). I don't know what your sprites look like, but you can make all sorts of things with text-sprites. And even if you can't make the whole sprite with text, you can fill in the missing pixels with Pxl-On( commands.

Re: Could this work?

symaxian 30 Sep 2007 00:16

Ive been working a test code out on the TI-84, im happy with the results and what this technique could do in the future, I particularly love the simplicity of the program and having the map data in a customizable and archivable list. Im picky with composing one game of many programs, so im wondering, why contain the text sprite generator in a different program if the above loops would apply to all the lists/maps.

Also how do you get a 5x7 sprite to the far right of the screen, if the pixels of the character would go offscreen then it doesnt show any of that character. Would I have to use Pxl-on( commands.

Last edited on 30 Sep 2007 02:00 by symaxian Show more

Re: Could this work?

burr 30 Sep 2007 04:24

The answer to your first question is available on the Optimization and Subprogram pages. I recommend reading through both pages, and really trying to understand the information. In regards to your sprite technique, the general idea is that you want to make your code as compact as possible, so that the calculator has to do as few operations as possible each time through the loop. This is what subprograms are used for.

The answer to your second question is simple: yes. By their design, text-sprites get displayed with characters overlapping each other, and because a text character cannot be partially displayed on the screen (i.e., you cannot display just one or two columns of a character), you can't get a sprite all the way over to the far right side of the screen. So, you need to use some Pxl-On( commands along with the text-sprite to get the desired sprite.