OpenEuphoria

Pastey Bouncing balls

• Posted by irv Aug 17, 2019

include GtkEngine.e
include GtkCairo.e 
 
constant fps = 60 
integer frameCounter = 0  
 
enum X,Y,RAD,XSPD,YSPD,COLOR 
object balls = {{10,20,20,6,4,"red"},{30,30,20,5,4,"green"}}  
 
constant rad360 = 6.283185307179586  -- full circle in radians; 
 
constant      
    disp = create(GdkDisplay), 
    scrn = get(disp,"default screen"), 
    win = create(GtkWindow,"title=Bouncing Ball,size=800x450,border=10,$destroy=Quit"), 
    pan = create(GtkBox,"orientation=vertical,spacing=10"), 
    screen = create(GtkDrawingArea,"background=white"), 
    lbl = create(GtkLabel), 
    box = create(GtkButtonBox), 
    btn1 = create(GtkButton,"gtk-quit","Quit"), 
    btn2 = create(GtkToggleButton,"Pause","Update"), 
    tic = create(GTimeout,1000/fps,call_back(routine_id("Update"))), 
    tok = create(GTimeout,1000,call_back(routine_id("ResetCounter"))) 
 
    add(win,pan) 
    pack(pan,screen,1,1) 
    add(box,{btn1,lbl,btn2}) 
    pack(pan,-box) 
 
show_all(win) 
 
integer screen_width, screen_height  
 
{screen_width,screen_height} = get(win,"size")  -- allow for window borders; 
 
for i = 1 to length(balls) do 
    balls[i][X] = rand(screen_width) / 2  
    balls[i][Y] = rand(screen_height) / 2  
end for 
 
main() 
 
--------------------------------- 
global function ResetCounter() -- reset value for fps display; 
------------------------------- 
set(lbl,"text",sprintf("%d fps",frameCounter)) 
frameCounter = 0 
return 1 
end function 
 
---------------------------------------------- 
function CollideCircles(object A, object B) --  
---------------------------------------------- 
atom x = A[X] - B[X] 
atom y = A[Y] - B[Y] 
atom centerDistanceSq = x * x + y * y -- squared distance 
atom radius = A[RAD] + B[RAD] 
atom radiusSq = radius * radius 
return centerDistanceSq <= radiusSq 
end function 
 
------------------------------------------- 
global function Update(atom ctl, atom data) -- 
---------------------------------------------- 
if get(btn2,"active") then -- pause button is depressed; 
 return 1  
end if  
 
{screen_width,screen_height} = get(win,"size") - {20,60}  -- in case changed; 
 
for i = 1 to length(balls) do 
	          
    balls[i][X] += balls[i][XSPD]  
    balls[i][Y] += balls[i][YSPD] 
	 
    if (balls[i][X] <= balls[i][RAD]) or (balls[i][X] >= screen_width - balls[i][RAD]) then 
        balls[i][XSPD] *= -1 
    end if 
     
    if (balls[i][Y] <= balls[i][RAD]) or (balls[i][Y] >= screen_height - balls[i][RAD]) then 
        balls[i][YSPD] *= -1 
    end if 
 
end for 
 
if CollideCircles(balls[1],balls[2]) then  
        balls[1][XSPD] *= -1  
        balls[1][YSPD] *= -1 
        balls[2][XSPD] *= -1  
        balls[2][YSPD] *= -1  
end if  
     
frameCounter += 1  
 
atom cr = create(GdkCairo_t,get(screen,"window")) 
 
set(cr,{ -- clear screen; 
    {"source rgba",255,255,255,255}, 
    {"operator",CAIRO_OPERATOR_SOURCE}, 
    {"paint"}})	 
    
for i = 1 to length(balls) do 
 set(cr,{ -- draw ball A 
    {"color",balls[i][COLOR]}, 
    {"arc", balls[i][X], balls[i][Y], balls[i][RAD], 0, rad360}, -- full circle; 
    {"fill"}}) 
end for 
 
set(cr,"destroy") 
 
return 1 
end function