Help the circle find the text! Its for a good cause!

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frostyrootbeer

21

Years of Service

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Joined: 23rd Dec 2002

Location: Afghanistan

Posted: 28th Jan 2003 06:13

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As you see i have been making some modifications to one of the DB tutorials, but have encountered a problem
I wan't to display "You got the health" when the user brings the circle over the "health pickup" text, but the way I have it set up you have to get it exactly on the coordinates to trigger the event or you can trigger wrongly. Is there a way to display the text if the user gets the circle in a coordinate box or something? Thanks in advance.

hide mouse
rem Set a coordinate in the middle of the screen
x=320
y=240

rem Actuvate manual sync
sync on

rem Begin main loop
do

rem Clear the screen each cycle
cls

health$ = "health pickup"

rem Show the current inkey$ and scancode value
set cursor 0,10
print "Try using ARROW KEYS, CONTROL, SPACEBAR, SHIFT and RETURN"
print "Try pressing the RIGHT CONTROL KEY to flag Keystate 157"
print "Inkey$()=";inkey$();"  Scancode=";scancode();"  Keystate(157)=";keystate(157)
print "X = ", x, "Y = ",  y
text 100,200, health$
rem Move the coordinate based on the keyboard input
if upkey()=1 then y=y-3
if downkey()=1 then y=y+4
if leftkey()=1 then x=x-4
if rightkey()=1 then x=x+4
rem make it so the circle cannot go offscreen
if y = 500 then y = y - 300
if y = 6 then y = y + 300
if x = 620 then x = x - 300
if x = 0 then x = x + 300
rem "pick" up "health"
if x + y = 350 then print "you got the health!"

rem Set the ink color based on the keyboard control keys
if controlkey()=1 then ink rgb(255,0,0),0
if shiftkey()=1 then ink rgb(0,255,0),0
if spacekey()=1 then ink rgb(0,0,255),0
if returnkey()=1 then ink rgb(64,0,64),0
if escapekey()=1 then end

rem Draw a circle at the coordinate
circle  x,y,20

rem Update screen
sync

rem End the loop
loop

+ Code Snippet

hide mouse
rem Set a coordinate in the middle of the screen
x=320
y=240

rem Actuvate manual sync
sync on

rem Begin main loop
do

rem Clear the screen each cycle
cls

health$ = "health pickup"




rem Show the current inkey$ and scancode value
set cursor 0,10
print "Try using ARROW KEYS, CONTROL, SPACEBAR, SHIFT and RETURN"
print "Try pressing the RIGHT CONTROL KEY to flag Keystate 157"
print "Inkey$()=";inkey$();"  Scancode=";scancode();"  Keystate(157)=";keystate(157)
print "X = ", x, "Y = ",  y
text 100,200, health$
rem Move the coordinate based on the keyboard input
if upkey()=1 then y=y-3
if downkey()=1 then y=y+4
if leftkey()=1 then x=x-4
if rightkey()=1 then x=x+4
rem make it so the circle cannot go offscreen
if y = 500 then y = y - 300
if y = 6 then y = y + 300
if x = 620 then x = x - 300
if x = 0 then x = x + 300
rem "pick" up "health"
if x + y = 350 then print "you got the health!" 


rem Set the ink color based on the keyboard control keys
if controlkey()=1 then ink rgb(255,0,0),0
if shiftkey()=1 then ink rgb(0,255,0),0
if spacekey()=1 then ink rgb(0,0,255),0
if returnkey()=1 then ink rgb(64,0,64),0
if escapekey()=1 then end

rem Draw a circle at the coordinate
circle  x,y,20

rem Update screen
sync

rem End the loop
loop

words to live by.... Newsgeek.tripod.com

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Fluffy Paul

21

Years of Service

User Offline

Joined: 16th Dec 2002

Location: United Kingdom

Posted: 29th Jan 2003 18:54

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What you need to do is keep track of the size of the "circle" which I assume is the object the player is controlling, and you have to know how large a target object is. There are two ways you can detect for a collision: Using a square collision zone and using a circular one.
A square collision zone is simple: it has a left and right x coordinate and a top and bottom y coordinate. To check if something (at coordinates x,y) is in the zone you use this if statement:

+ Code Snippet

if x>=leftx and x<=rightx and y>=topx and y<=bottomy
   rem x and y inside zone!
endif

If two things use a square zone then you have to check twice. Say it's a bullet and another sprite. The first thing you do is work out which one is smaller. Now the first check is to see if the smaller sprite's top left corner is inside the larger sprite's zone, then you check if the smaller sprite's bottom right corner is in the same zone. If so then you can trigger a condition of your choice using IF statements.

Using a circular collision detection method basically involves calculating the range between two points on the screen. If the range is smaller than a certain value then the two objects have collided.
The formula for calculating the range between coordinates x1,y1 and x2,y2 is:

((x1-x2)^2 + (y1-y2)^2)^0.5

Note - no trigonometry! Although raising to the power of 0.5 is the same as doing the square root.

Each of your objects that uses this circular collision detection should have a collision range assigned to them. When you've worked out the range between two points you should check both objects to see if the range is less than their collision range. If this is so then BOTH objects have collided (not just the one who's collision radius was lower than the range)!

Ending a sentence with a French word is so passé

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frostyrootbeer

21

Years of Service

User Offline

Joined: 23rd Dec 2002

Location: Afghanistan

Posted: 30th Jan 2003 01:45

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Thanks very much

equation for any multiplayer fps
the best weapon in the game = "noob cannon"

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