OpenEuphoria

1. Shooting Multiple Bullets

• Posted by Icy_Viking Feb 07, 2020
• 1356 views

Hello all,

I am having a slight problem. I am trying to shoot multiple bullets, but I can only fire one.

atom Width=1024 
atom Height=720 
constant TRUE=1 
constant FALSE=0 
 
InitWindow(Width,Height,"Shump") 
 
SetTargetFPS(60) 
 
atom black = bytes_to_int({0,0,0,0}) 
 
atom red = bytes_to_int({255,0,0,255}) 
 
atom bullet_x = GetScreenWidth() / 2 
atom bullet_y = GetScreenHeight() / 2 
 
atom bullet_speed = 0.030 
 
integer bullet_visible = FALSE 
 
sequence bullets = {} 
 
while not WindowShouldClose() do 
 
	if IsKeyPressed(KEY_SPACE) and bullet_visible = FALSE then 
		bullet_visible = TRUE 
	end if 
	 
	if (bullet_visible) then 
		bullet_x += bullet_speed 
	end if 
	 
	if (bullet_x >= GetScreenWidth()) then 
		bullet_visible = FALSE 
	end if 
	 
	BeginDrawing() 
	 
	ClearBackground(black) 
	 
	if (bullet_visible = TRUE) then 
			DrawCircleV(bullet_x,bullet_y,20,red) 
	end if 
	 
	EndDrawing() 
 
end while 
 
CloseWindow() 

3. Re: Shooting Multiple Bullets

• Posted by Icy_Viking Feb 08, 2020
• 1273 views

Thank you. However I had to fix a couple of things. Like putting the for loop in between the begin and end drawing functions. Also, when the last bullet of the array is done, there is a subscript value out of bounds error.

Value 1 is out of bounds, reading from a sequence length of 0 in subscript #1 of "bullets"

without warning 
 
include std/machine.e 
include std/get.e 
include std/convert.e 
 
include EuRaylib.ew 
 
include flags.e 
 
atom Width=1024 
atom Height=720 
constant TRUE=1 
constant FALSE=0 
 
InitWindow(Width,Height,"Shump") 
 
SetTargetFPS(60) 
 
atom black = bytes_to_int({0,0,0,0}) 
 
atom red = bytes_to_int({255,0,0,255}) 
 
atom bullet_speed = 5.0 
 
integer bullet_visible = FALSE 
constant X=1,Y=2 
 
sequence bullets = {} 
 
while not WindowShouldClose() do 
 
	if IsKeyPressed(KEY_SPACE) then 
		atom bullet_x = GetScreenWidth() / 2 
		atom bullet_y = GetScreenHeight() / 2 
		bullets = append(bullets,{bullet_x,bullet_y}) 
	end if 
 
	BeginDrawing() 
	 
	ClearBackground(black) 
	 
	for i = length(bullets) to 1 by -1 do 
		bullets[i][X] += bullet_speed 
		 
		if (bullets[i][X] >= GetScreenWidth()) then 
			bullets = remove(bullets,i) 
		end if 
		 
		DrawCircleV(bullets[i][X],bullets[i][Y],20,red) 
	end for 
	 
	EndDrawing() 
 
end while 
 
CloseWindow() 

5. Re: Shooting Multiple Bullets

• Posted by SDPringle Feb 09, 2020
• 1241 views

	for i = length(bullets) to 1 by -1 do  
		bullets[i][X] += bullet_speed  
		  
		if (bullets[i][X] >= GetScreenWidth()) then  
			bullets = remove(bullets,i)  
		end if  
		  
		DrawCircleV(bullets[i][X],bullets[i][Y],20,red)  
	end for  

If you remove from an array (bullets) when you have a for loop iterating over it, you shouldn't try to draw that bullet in the DrawCircleV line:

	for i = length(bullets) to 1 by -1 do  
		bullets[i][X] += bullet_speed  
		  
		if (bullets[i][X] >= GetScreenWidth()) then  
			bullets = remove(bullets,i) 
                        -- bullets[i] may no longer exist or 
                        -- it refers to something that has already been drawn. 
                        -- Go to the next iteration now! 
                        continue 
		end if 
		  
		DrawCircleV(bullets[i][X],bullets[i][Y],20,red)  
	end for