Collision Sprite with a tile

[tiberiyltim]

How detect collision Sprite on Tile?

my code:

'Tiles line
	for y=24 to 24
		for x=0 to 39
			drawtile &h39,x,y
		next
	next

'Player data
	Player1=AddSprite(4,3)
	PropSprite Player1,128,0
	MoveSprite Player1,130,60

	while 1

'down Sprite
	if Stop=0 then ShiftSprite Player1,0,+2

'stop Sprite???
	if 32+SpritePosY(Player1)=&h39 then
	Stop=1
	endif

	Sleep 1

	wend

[nitrofurano1]

in theory, i think it depends on how you have your tiles organized (a group of tiles that is not related to collision and a group that is) on the video ram, or keep checking the sprite position on a map from rom - i guess this was how games for colecovision, master system and msx were made related to this

[Deleted]

You could use the readtile function:
devster.monkeeh.com/sega/basiegaxorz/basiegaxorz_full.html#function_readtile

I've been told over the years that reading video memory is slow. You could create a collision map instead using an array to represent the current level/tile layout.

[nitrofurano1]

i can’t remember what i used on Boriel’s ZX-Basic Compiler in these situations, they have sprite-tile collision somehow:
- www.boriel.com/wiki/en/index.php/ZX_BASIC:Released_Programs_-_MSX#The_Ruins_of_Machi_Itcza
- www.boriel.com/wiki/en/index.php/ZX_BASIC:Released_Programs_-_ColecoVision#H7N9 (this one doesn’t uses sprites, but might be interesting for analising)
perhaps they might be useful, since colecovision and msx vdp works very similarly to genesis

[tiberiyltim]

Sept 6, 2016 6:38:41 GMT -5 @theloon said:

You could use the readtile function:
devster.monkeeh.com/sega/basiegaxorz/basiegaxorz_full.html#function_readtile
I've been told over the years that reading video memory is slow. You could create a collision map instead using an array to represent the current level/tile layout.

Collision map not displaced through scroll?

use the readtile function...

dim positionx(50) as integer
dim positiony(50) as integer

positionx=130
positiony=60

'Tiles line
for y=24 to 24
for x=0 to 39
drawtile &h39,x,y
next
next

'Player data
Player1=AddSprite(4,3)
PropSprite Player1,128,0
MoveSprite Player1,positionx,positiony

while 1

'down Sprite
if Stop=0 then ShiftSprite Player1,0,+2

a=readtile(positionx(0),positiony(0))

'stop Sprite???
if a=&h39 then
Stop=1
endif

Sleep 1

wend

not work

[Deleted]

There's a lot of methods for doing this, but it really all depends on what your engine needs as well.

The first thing you'll need to do is convert your sprite coordinates to tile coordinates. Let's assume it's an 8x8 pixel sprite:
sprx = (spriteposx(MySprite) - 128) / 8
spry = (spriteposy(MySprite) - 128) / 8

(you can substitute >> 3 in place of /8)

Then, what you can do is reload your tile map and use the coordinates as your offset


MapOffset = ((spry + y_move) * MapX) + sprx + x_move


Reload MyMap, MapOffset
ReadInt z

The y_move would be -1 if you're going up, +1 if you're going down, and 0 if you're not moving in the Y direction
The x_move would be -1 if going left, +1 if going right, and 0 if not moving on the X axis

Now, why the ReadInt z?

What I do is assign a number range for my tiles (to keep it simple) to note which ones are walkable/passable and which ones aren't passable. For example, tiles 1 to 50 are walkable tiles (grass, regular ground, etc), and everything else is impassable.

Next, I do something along the lines of:

If z > 0 And z < 51 Then
' move my sprite routine
End If

[tiberiyltim]

elusive, you have easy to use example "scroll Map"?

[Deleted]

I don't, but moon posted an example some time back that showed collision for tiles, and later in the thread has an example with scrolling added. Here's the thread devster.proboards.com/thread/760/castlevania

Hope this helps!

[tiberiyltim]

There there is no scrolling map.
Sorry, Thanks!

[Deleted]

It's the 2nd example near the bottom of the page.

[nemezes]

Sept 7, 2016 15:56:31 GMT -5 @elusive said:

There's a lot of methods for doing this, but it really all depends on what your engine needs as well.

The first thing you'll need to do is convert your sprite coordinates to tile coordinates. Let's assume it's an 8x8 pixel sprite:
sprx = (spriteposx(MySprite) - 128) / 8
spry = (spriteposy(MySprite) - 128) / 8

(you can substitute >> 3 in place of /8)

Then, what you can do is reload your tile map and use the coordinates as your offset


MapOffset = ((spry + y_move) * MapX) + sprx + x_move


Reload MyMap, MapOffset
ReadInt z

The y_move would be -1 if you're going up, +1 if you're going down, and 0 if you're not moving in the Y direction
The x_move would be -1 if going left, +1 if going right, and 0 if not moving on the X axis

Now, why the ReadInt z?

What I do is assign a number range for my tiles (to keep it simple) to note which ones are walkable/passable and which ones aren't passable. For example, tiles 1 to 50 are walkable tiles (grass, regular ground, etc), and everything else is impassable.

Next, I do something along the lines of:

If z > 0 And z < 51 Then
' move my sprite routine
End If

I was trying to understand what was that shift left right in binary.. Now I figure out what it is.. so simple

x<<n is the same as x*(2^n).

thanks a lot

yes, I am still learning how to code.