hi.

I think, the few lines of code are not enough to find the error.
If you want me to check it, please send me the entire source code
(email: s_buschmann@gmx.de)

But i try a guess :
When you checked the collision, you used the same index variable
for the bot and for the laser. But why should they always be the same?
I think the collision detection should be done this way:

code:

for (i=0; i<=MAX_BOB; i++){  for (j=0; j<=MAX_LASER; j++)  {    if (Collision_BOBS(&laser[j],⊥) &&     bot.state == BOT_STATE_ON)<BR>    {<BR>      laser[j].state = LASER_STATE_OFF;<BR>      start_Burst(laser[j].x,laser[j].y,<BR>      68+rand()%12,54+rand()%10,<BR>      bot.xv>>1,bot.yv>>1);<BR>      bot.state = BOT_STATE_OFF;<BR>    }<BR>  }<BR>}<BR></pre><HR></BLOCKQUOTE><P>But this is just a guess.<P>good luck!<P><BR>——————<BR>Philippo<BR>s_buschmann@gmx.de <A HREF="http://privat.schlund.de/Gerio" TARGET=_blank>http://privat.schlund.de/Gerio</A> <P><BR>[This message has been edited by Philippo (edited October 22, 1999).]<P>[This message has been edited by Philippo (edited October 22, 1999).]<p>[This message has been edited by Philippo (edited October 22, 1999).]

If you are using Draw_BOB() to display the bot, then you need to use the functions: Hide_BOB() and Show_BOB() to set the visibility. If you look in the engines header file you will notice,

#define BOB_ATTR_VISIBLE 16 // bob is visible

This bit is used for visibility in the variable "bot.attr" not "bot.state". So, to check if a bot is visible:

if (bot.attr & BOB_ATTR_VISIBLE) {}

Draw_BOB() checks the visibilty with:

if (!(bot->attr & BOB_ATTR_VISIBLE))
return(1);

Hope that helps.

Thanks so much for your replys. This is how I am drawing, moving, detecting the bot (I am now using Hide_BOB and bot.attr that masterr pointed out):

void Draw_Bot(void)
{

if (bot.attr & BOB_ATTR_VISIBLE)
{
Draw_BOB(⊥,lpddsback);

Animate_BOB(⊥);

}

}

void Move_Bot(void)
{

if (bot.attr & BOB_ATTR_VISIBLE)
{
Move_BOB(⊥);
}

}

if (Collision_BOBS(&laser[index],⊥) && bot.attr && BOB_ATTR_VISIBLE)
{

laser[index].state = LASER_STATE_OFF;
Start_Burst(laser[index].x, laser[index].y,
68+rand()%12,54+rand()%10,
bot.xv>>1, bot.yv>>1);

Hide_BOB(⊥);

}

(Note: I have taken out the [0], and [index]) Now this code stops drawing (or hides) the bot but it still detects the collision with the laser. So it basically has to be in the collision code.

Thanx again for the help,
ViPeR

You will also want to change the lasers in the same way as the bot. I think that your collision test should look like this:

if ( bot.attr & BOB_ATTR_VISIBLE )
{
for (index=0; index{
if ( (laser[index].attr & BOB_ATTR_VISIBLE) && Collision_BOBS(&laser[index],⊥) )
{
Hide_BOB( laser[index] );
.
.
.
}
}
}

YES! That worked, thanks so much masterr and Philippo I couldn't have done this without you.

Thanx again,
ViPeR

Lets try that again:

if ( bot.attr & BOB_ATTR_VISIBLE )

{

for (index=0; index

{

if ( (laser[index].attr
& BOB_ATTR_VISIBLE) && Collision_BOBS(&laser[index],&bot)
)

{


Hide_BOB( laser[index] );


...

}

}

}

Ok I have been working on this darn problem for about a week and a half now (yes I am a beginner). I am running out of ideas fast so I thought I might turn here for any suggestions anyone has. The following code sets up an enemy robot (bot) on the screen and then the collision code tests if a laser hits it. If it does it sets the laser's state to off (not being drawn so it doesn't look like it just goes right through the enemy) starts the explosions and then turns the bot off. Thats my problem it never turns the bot off (not drawn on the screen anymore). Heres the problem code:

I defined the states:
#define MAX_BOT 1
#define BOT_STATE_OFF 0
#define BOT_STATE_ON 1

then the bot (yes Im using the engine from the book Game Programming for Dummies):
BOB bot[MAX_BOT];

Then I set up a Init_Bot function:
void Init_Bot(void)
{
Load_Bitmap_File(&bitmap8bit, "BOT8.BMP");

Create_BOB(⊥[0],0,0,37,36,3,
BOB_ATTR_VISIBLE | BOB_ATTR_MULTI_FRAME,
DDSCAPS_SYSTEMMEMORY);

bot[0].state = BOT_STATE_OFF;

for (int index=0; index<2; index++)
Load_Frame_BOB(⊥[0],&bitmap8bit,index,index,0,BITMAP_EXTRACT_MODE_CELL);

Set_Pos_BOB(⊥[index],320 ship.width/2,100);

Set_Anim_Speed_BOB(⊥[index],1);

Unload_Bitmap_File(&bitmap8bit);

}

Then I set up Delete_Bot, Move_Bot, and Draw_Bot. Those are pretty much self explanatory but they each test if the bot = state on and then do what there meant to do. If it is BOT_STATE_OFF then it doesn't do those things (except for the Delete_Bot). Then here is the collision code:

if (Collision_BOBS(&laser[index],⊥[index]) && bot[index].state == BOT_STATE_ON)
{

laser[index].state = LASER_STATE_OFF;
Start_Burst(laser[index].x, laser[index].y,
68+rand()%12,54+rand()%10,
bot[index].xv>>1, bot[index].yv>>1);

bot[index].state = BOT_STATE_OFF;

}

I think the problem is somewhere in the Init_Bot code or the collision code but I don't know which. Does anyone have any suggestions of what to do?

Thanx for the info,
ViPeR

Yea, I fixed the last code when I put it in. Thanx again masterr.

ViPeR