Shooting Snowballs

Blitz3D Forums/Blitz3D Beginners Area/Shooting Snowballs

Happy Llama (Posted 2012) [#1]

I'm making a game where you throw snowballs at the enemy. Its not done yet so some things (like the Types) are not really important right now. Any way I've set up some code to fire a snowball every time the left mouse button is pressed. When I fire about 6-8 snowballs it comes up with the error "Illegal memory address" Can some one tell me what i'm doing wrong?! Code: Graphics3D 800,600,0,1 SetBuffer BackBuffer() ;variables Const spacebar=57,escape=1,leftkey=208,rightkey=205 gravity=0.3 cam_y#=-3 cam_x#=0 HidePointer shoosh=LoadSound("swoosh.wmv") ;Types Type p_snowball Field damage=5 Field psys=0 End Type Type e_snowball Field damage=5 Field esys=0 End Type Type player Field health=100 End Type Type enemy Field health=100 End Type AmbientLight 255,255,255 ;Light sun=CreateLight() ;Player player=CreateCamera() CameraFogRange player,0.1,400 CameraFogMode player,True CameraClsColor player,100,130,150 CameraFogColor player,100,130,150 ;Terrain ground=CreatePlane() PositionEntity ground,0,-5,0 EntityColor ground,200,200,200 ;Sky sky=CreatePlane() PositionEntity sky,0,100,0 RotateEntity sky,-180,0,0 ;Sky texture skytex=LoadTexture("sky.jpg") EntityTexture sky,skytex ScaleTexture skytex,5,5 ScaleTexture skytex,500,500 ;Load the enemy enemy=LoadMesh("enemy.3ds") PositionEntity enemy,0,-4,30 ScaleEntity enemy,0.5,0.5,0.5 ;Make the snow forts: ;Fort 1 fort1=LoadMesh("snowfort.3ds") PositionEntity fort1,0,-3.5,4 EntityColor fort1,255,255,255 ScaleEntity fort1,1,1,2.5 RotateEntity fort1,0,-90,0 ;Fort 2 fort2=CreateCube() PositionEntity fort2,0,-4,30 EntityColor fort2,255,255,255 ScaleEntity fort2,2,1,1 ;Player Snowballs fullcart=25 Dim bullet(fullcart) For i=0 To fullcart bullet(i)=CreateSphere(36) ScaleEntity bullet(i),0.2,0.2,0.2 HideEntity bullet(i) Next ;Making it snow! Dim snowflake(1000) For p=0 To 1000 snowflake(p)=CreateSphere() ScaleEntity snowflake(p),0.05,0.05,0.05 PositionEntity snowflake(p),Rnd(-50,50),Rnd(1,100),Rnd(-50,50) Next ;############### ;# Main Loop # ;############### While Not KeyDown (escape) ;Shooting the player snowballs If MouseDown(1) Then ShowEntity bullet(t) PositionEntity bullet(t),EntityX(player,1),EntityY(player,1),EntityZ(player,1) RotateEntity bullet(t),EntityPitch#(player),EntityYaw#(player),EntityRoll#(player) t=t+1 EndIf For q=0 To fullcart MoveEntity bullet(q),0,snowball_y,0.5 Next ;Move the snow downwards For l=0 To 1000 MoveEntity snowflake(l),0,Rnd(-0.002,-0.1),0 Next ;duck If KeyDown(57) Then cam_y=-3.7 Else cam_y=-3 EndIf PositionEntity player,cam_x,cam_y,3 ;straffting If KeyDown(30) Then cam_x=cam_x-0.1 If KeyDown(32) Then cam_x=cam_x+0.1 If cam_x > 0.5 Then cam_x=0.5 If cam_x < -0.5 Then cam_x=-0.5 ;point the enemy at the player PointEntity enemy,player ;FPS Camera Stuff mxs#=mxs#+MouseXSpeed() mys#=mys#+MouseYSpeed() If mxs# > 100 Then mxs# = 100 If mxs# < -100 Then mxs# = -100 If mys# > 40 Then mys# = 40 If mys# < -80 Then mys# = -80 RotateEntity player,mys#,-mxs#,0 ;MoveMouse 400,300 RenderWorld UpdateWorld Color 0,0,0 Rect 10,10,100,100,False Flip Wend End Last edited 2012

Matty (Posted 2012) [#2]

First - put debug mode on - that should help you with finding where the error is. I would guess however it is because you are exceeding the bounds of the array "bullet". Notice that when the mouse is pressed you increment the bullet's index "t" but you never do anything to prevent it going outside the maximum size of the array (25 in this case).

Drak (Posted 2012) [#3]

I've updated your code a bit. I would suggest changing from using an array for bullets to using types. It's much easier to manage in my opinion. Read through this as I've commented all the lines I added or changed. (I also had to comment out the media as I did not have it) Graphics3D 800,600,0,1 SetBuffer BackBuffer() ;variables Const spacebar=57,escape=1,leftkey=208,rightkey=205 gravity=0.3 cam_y#=-3 cam_x#=0 HidePointer ;shoosh=LoadSound("swoosh.wmv") ;Types Type p_snowball Field damage=5 Field psys=0 End Type Type e_snowball Field damage=5 Field esys=0 End Type Type player Field health=100 End Type Type enemy Field health=100 End Type ;----------------------------------------------------------------------------------------------------- ;----------------------------------------------------------------------------------------------------- ;------------------------------------------------------------------------------------------- ;I added these lines here: Take a look at how they work. I find it MUCH easier to use a ;type for projectiles instead of an array. Global magazine = 25 ;this can hold the total number of snowballs the player has available (25) Type snowball Field mesh ;This will hold the actual physical mesh of the snowball Field id ;This can tell you who threw the snowball, such as 1 for player, 2 for enemy Field damage;This can hold the value you want for damage as you had above End Type ;----------------------------------------------------------------------------------------------------- ;----------------------------------------------------------------------------------------------------- AmbientLight 255,255,255 ;Light sun=CreateLight() ;Player player=CreateCamera() CameraFogRange player,0.1,400 CameraFogMode player,True CameraClsColor player,100,130,150 CameraFogColor player,100,130,150 ;Terrain ground=CreatePlane() PositionEntity ground,0,-5,0 EntityColor ground,200,200,200 ;Sky sky=CreatePlane() PositionEntity sky,0,100,0 RotateEntity sky,-180,0,0 ;Sky texture ;skytex=LoadTexture("sky.jpg") ;EntityTexture sky,skytex ;ScaleTexture skytex,5,5 ;ScaleTexture skytex,500,500 ;Load the enemy ;enemy=LoadMesh("enemy.3ds") enemy=CreateCylinder() PositionEntity enemy,0,-4,30 ScaleEntity enemy,0.5,0.5,0.5 ;Make the snow forts: ;Fort 1 fort1=CreateCube() PositionEntity fort1,0,-3.5,4 EntityColor fort1,255,255,255 ScaleEntity fort1,1,1,2.5 RotateEntity fort1,0,-90,0 ;Fort 2 fort2=CreateCube() PositionEntity fort2,0,-4,30 EntityColor fort2,255,255,255 ScaleEntity fort2,2,1,1 ;Player Snowballs ;----------------------------------------------------------------------------------------------------- ;----------------------------------------------------------------------------------------------------- ;create just a simple bullet mesh for the snowballs bullet=CreateSphere(36) ScaleEntity bullet,0.2,0.2,0.2 HideEntity bullet ;----------------------------------------------------------------------------------------------------- ;----------------------------------------------------------------------------------------------------- ;Making it snow! Dim snowflake(1000) For p=0 To 1000 snowflake(p)=CreateSphere() ScaleEntity snowflake(p),0.05,0.05,0.05 PositionEntity snowflake(p),Rnd(-50,50),Rnd(1,100),Rnd(-50,50) Next ;############### ;# Main Loop # ;############### While Not KeyDown (escape) ;----------------------------------------------------------------------------------------------------- ;----------------------------------------------------------------------------------------------------- ;Shooting the player snowballs If MouseHit(1) And magazine > 0 ;check if the player has snowballs left (more than 0) s.snowball = New snowball ;create a new snowball s\mesh = CopyEntity(bullet) ;we'll copy the bulletmesh you've already loaded s\id = 1 ;Lets say 1 is from the player, 2 is from the enemy s\damage = 5 ;Damage will be 5 still PositionEntity s\mesh,EntityX(player),EntityY(player),EntityZ(player) ;position it correctly RotateEntity s\mesh, EntityPitch(player),EntityYaw(player),EntityRoll(player) ;and orientate it correctly magazine = magazine -1 ;this will subtract 1 snowball from the player's stash of snowballs End If ;here is where we'll move the snowballs For s.snowball = Each snowball ;for each snowball MoveEntity s\mesh, 0,0,1 ;move it forward If Abs(EntityZ(s\mesh)) > 400 ;if the snowball gets beyond 400 units FreeEntity s\mesh ;free the mesh from memory Delete s ;and delete the reference to it End If Next ;----------------------------------------------------------------------------------------------------- ;----------------------------------------------------------------------------------------------------- ;Move the snow downwards For l=0 To 1000 MoveEntity snowflake(l),0,Rnd(-0.002,-0.1),0 Next ;duck If KeyDown(57) Then cam_y=-3.7 Else cam_y=-3 EndIf PositionEntity player,cam_x,cam_y,3 ;straffting If KeyDown(30) Then cam_x=cam_x-0.1 If KeyDown(32) Then cam_x=cam_x+0.1 If cam_x > 0.5 Then cam_x=0.5 If cam_x < -0.5 Then cam_x=-0.5 ;point the enemy at the player PointEntity enemy,player ;FPS Camera Stuff mxs#=mxs#+MouseXSpeed() mys#=mys#+MouseYSpeed() If mxs# > 100 Then mxs# = 100 If mxs# < -100 Then mxs# = -100 If mys# > 40 Then mys# = 40 If mys# < -80 Then mys# = -80 RotateEntity player,mys#,-mxs#,0 ;MoveMouse 400,300 RenderWorld UpdateWorld Color 0,0,0 Rect 10,10,100,100,False ;----------------------------------------------------------------------------------------------------- ;Display how many showballs you have left: Text 350,0,"Snowballs Left: " + magazine ;here's where we make sure the snowballs are deleted properly ;count them count = 0 ;create a variable to hold the amount of snowballs counted For s.snowball = Each snowball ;for each snowball count = count + 1 ;add 1 to the count! Next Text 350,10,"Snowballs tracked: " + count ;then display it here. ;This can obviously be deleted later as it's just for debugging purposes ;----------------------------------------------------------------------------------------------------- Flip Wend End You can of course put each process into it's own function to greatly simplify the code. I've also added the ability to count each bullet and delete it when it gets too far off the screen.

Happy Llama (Posted 2012) [#4]

Edit: Any suggestions on reloading? Last edited 2012

Happy Llama (Posted 2012) [#5]

I'll just make a new post.