Isometric in SDL?

SDL Development
1

you mean to render a screen in isometric perspective using SDL, such as for a 2D game? It’s simple, just map the coordinates out yourself.
of course SDL doesn’t provide facilities for that, it’s a simple layer over the operating system code; not a generic game programming library.

It’s really easy though. If you think of each pixel as a square on the floor, when you move across the screen horizontally or vertically you’re changing both X and Y values by the same amount; and if you move perfectly diagonally across the screen (IE, the same change in screen’s X and screen’s Y) then you’re only changing one while the other is constant.

It sounds a lot more confusing than it really is.

Or maybe you’re talking about something else completely and I’m just making an ass out of myself here. :slight_smile:

2

I am talking about moving my player Isometricly

like this

\ /
\ /
\ /

basically I am not sure how the math would work. Any examples? I don’t want complete source dont get me wrong I am just new to Isometric math an it’s something you can’t find on the web much lol

3

What I do is represent everything in a standard 2D map,
but then simply display it using isometric tiles:

/
/

Because isometric makes it easy to do a 3rd dimension,
I create a basic little map that was WxHx2.
(The ground, and objects sitting on the ground.)

I then displayed them in such a way that things
overlapped correctly. A simple “painter’s method.”

for (z = 0; z < 2; z++) { /* Ground, then objects /
for (y = 0; y < 10; y++) { / Scrolling around a 10x10 view of the map /
for (x = 0; x < 10; x++) {
c = map[z][y + mapy][x + mapx]; / mapx,mapy is where we’ve scrolled */

    drawshape(CTRX + x * 32 - y * 32, TOPY + y * 16 + x * 16, c);

    /* CTRX,TOPY is top middle of where window into the map is to be drawn;
       tiles are 64x64 */
  }
}

}

Here are three example tiles (at approx 1/10th scale ;^) ):

  1. A cube:

    …XX…
    XXXXXX
    ==XX–On Fri, Nov 13, 2009 at 07:52:47PM -0800, Tivoilos wrote:

I am talking about moving my player Isometricly

===—
===—
…=-…

  1. Ground

    …
    …
    …
    …##…

    …##…

  2. Tree

    …88…
    .8888.
    …88…
    …||…
    …||…
    …

In this case, if I were to draw the ground first, then the wall, the
ground would be completely covered by my wall. But with the tree,
I get:

…88…
.8888.
…88…
…||…
##||##
…##…

And, of course, when multiple objects are drawn adjacent to each other,
they tile nicely:

          ......
          ......
       ............
       ............
    ..88....XX........
    .8888.XXXXXX......
    ..88..++XX--......
    ..||..+++---......
    ##||##+++---......
    ..######+-###.....
       ############
       ..########..
          ######
          ..##..

Or there 'bouts.

I wrote a little program that let me pan around an iso map.
It was about 415 lines of code. :slight_smile:

-bill!

4

There’s a whole subforum devoted to isometric game making over at gamedev.net.
As well as tutorials. You might want to check that out.

5

Tivoilos wrote:

I am talking about moving my player Isometricly

basically I am not sure how the math would work. Any examples? I don’t want complete source dont get me wrong I am just new to Isometric math an it’s something you can’t find on the web much lol

Like I said, to move diagonally you only change one isometric (x, y) coordinate value.
You’d probably want X to be moving like this \ and y to be moving like this /, or at least that’s how I usually do it (because, like I said, I like to think of it as rotating the scene 45 degrees)
So, to move your player like \ you’d only increment the x coordinate value. To move him like / you’d increment the y coordinate value.
To map those to screen coordinates, it’d be like: scr_x = iso_x - iso_y; scr_y = iso_x + iso_y;
The concept behind that is that scr_x should increase going across the screen from left to right, and scr_y should increase going across the screen from top to bottom.
Since iso_x increases going across the screen from top-left to bottom-right (), it increments both scr_x and scr_y with each increment.
Since iso_x increases going across the screen from top-right to bottom-left (/), it decrements scr_x and increments scr_y with each increment.

Of course, I’ve never written a complete isometric game, only toyed around with the perspective, so there are surely people more knowledgeable than myself worth discussing this with.

6

-sorry double post-

would it be more along the lines like this

Code:

int iso_x;
int iso_y;

int x = iso_x - iso_y;
int y = iso_x + iso_y;

void iso_key_input()
{
if(event.type == SDL_KEYDOWN)
{
switch(event.key.keysym.sym)
{
case SDLK_UP:
iso_x + =spriteheight /2; break;
iso_y + =spriteheight/2; break;

 case SDLK_DOWN:
 iso_x -= spriteheight/2;break;
 iso_y -= spriteheight/2;break;

}
}
}

something more along the lines of that?

7

Not so much.

Your first code was more correct, you just need to switch up and right. Also, are you new to programming? Why would you initialize x and y in the global scope?
try: #define SCR_X (iso_x - iso_y) and #define SCR_Y (iso_x + iso_y)

8

Hello LIBSDL!!!

perfect opurtunity for me to throw crazeeman0.4 in the mix!

its in the zip at http://www.crashedcomputers.co.uk/indexgames.php

it has 8 way isometric stuff going on, still a few rendering issues, but
nothing major. the code
is broken i think but one of the executables works, it also has a level
designer in there,
someone please step up and help me make my dream of an 8 way isometricish
pacman
clone a reality. the code is a mess, but its there for someone to finish…
i’m trying to get to
grips with basic SDL1.3 :wink: