;While you move Ship\x = Ship\x + Cosine(Ship\Angle - 90) Ship\y = Ship\y + Sine(Ship\Angle - 90) ;Continue looping

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MM out-
Thought travels much faster than sound, it is better to think something twice, and say it once, than to think something once, and have to say it twice.
"Frogs and Fauns! The tournament!" - Professor Winneynoodle/HanClinto
"Of course, prayer requires that you actually take the time to listen for His answer..." - I'msold4Christ
"I would much rather say that every time you make a choice you are turning the central part of you, the part of you that chooses, into something a little different from what it was before." -C.S. Lewis, Mere Christianity

I reserve the full right to change my views/theories at any time.

[This message has been edited by Mene-Mene (edited February 23, 2007).]

Or make set values, so like if character rotation Y = 90 (however you find out how to measure the rotation) and move up, or wherever. But the set value way is too manual and would be very time consuming for a top-down game. Now it would work perfectly for a side-scrolling game, if you were making one.

[This message has been edited by LAVA (edited March 04, 2007).]

Basically, you have to store a few things about your ship. Your coordinates (x and y values), your velocity (x and y values), and your heading (a single angle).

; game loop ; movement update section ; Rotation if (LeftArrow) then ; If the player is pressing left ; Then rotate the ship ccw ship\heading = ship\heading - ship\turnSpeed end if if (RightArrow) then ; If the ship is pressing right ; Then rotate the ship cw ship\heading = ship\heading + ship\turnSpeed end if ; Thrusters if (UpArrow) then ; If the player is pressing the up arrow ; then add some thrust in the direction of their heading ship\xVel = ship\xVel + Cosine(ship\heading - 90) * ship\thrustForce ship\yVel = ship\yVel + Sine(ship\heading - 90) * ship\thrustForce end if ; Then update the position according to their velocity ship\xPos = ship\xPos + ship\xVel ship\yPos = ship\yPos + ship\yVel

I'm just guessing at Blitz syntax from following Mene's example -- even though I'm sure it's wrong, I hope you get the basic gist of it.

All the best,
clint

[This message has been edited by HanClinto (edited March 06, 2007).]

if bulletangle = 0 then bulletdx := 0 bulletdy := 6 elsif bulletangle = 1 or bulletangle = 2 or bulletangle = 3 then bulletdx := -4 bulletdy := 6 elsif bulletangle = 4 or bulletangle = 5 or bulletangle = 6 then shipdx := -6 shipdy := 4 elsif bulletangle = 7 or bulletangle = 8 then bulletdx := -6 bulletdy := 2 elsif bulletangle = 9 then bulletdx := -6 bulletdy := 0 elsif bulletangle = 10 or bulletangle = 11 or bulletangle = 12 then bulletdx := -6 bulletdy := -2 elsif bulletangle = 13 or bulletangle = 14 or bulletangle = 15 then bulletdx := -6 bulletdy := -4 elsif shipangle = 16 or bulletangle = 17 then bulletdx := -4 bulletdy := -6 elsif bulletangle = 18 then bulletdx := 0 bulletdy := -6 elsif bulletangle = 19 or bulletangle = 20 or bulletangle = 21 then bulletdx := 2 bulletdy := -6 elsif bulletangle = 22 or bulletangle = 23 or bulletangle = 24 then bulletdx := 6 bulletdy := -4 elsif bulletangle = 25 or bulletangle = 26 then bulletdx := 6 bulletdy := -2 elsif bulletangle = 27 then bulletdx := 6 bulletdy := 0 elsif bulletangle = 28 or bulletangle = 29 or bulletangle = 30 then bulletdx := 6 bulletdy := 2 elsif bulletangle = 31 or bulletangle = 32 or bulletangle = 33 then bulletdx := 4 bulletdy := 6 elsif bulletangle = 34 then bulletdx := 2 bulletdy := 6 end if end if

I know you must have looked over and over the trig stuff and just now have moved to something which you are able to get done your own way, and you understand what it's doing

keep on learning your doing pretty well in my opinion

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www.auran.com

ship.x + ( ship.width / 2 )
and
ship.y + ( ship.height / 2 )

I'm working on a movement system similar to this one - but ran into some problems.

In main loop:
INC ship1.xPos, ship1.xVel
INC ship1.yPos, ship1.yVel

and in sub:

IF KEY(200) ship1.xVel = ship1.xVel - COS(ship1.heading-90) * thrust ship1.yVel = ship1.yVel - SIN(ship1.heading-90) * thrust ELSE IF KEY(208) ship1.xVel = ship1.xVel + COS(ship1.heading-90) * thrust ship1.yVel = ship1.yVel + SIN(ship1.heading-90) * thrust

Looks fine, right -
Problem is, the object being moved will go off in seemingly random directions - never at the right angle.

2. Sine is for Y, Cosine for X:
ship1.xVel = ship1.xVel + SIN(ship1.heading-90) * thrust
3. Wouldn't it be easier for 208 to be absolute of 200?

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MM out-
Thought travels much faster than sound, it is better to think something twice, and say it once, than to think something once, and have to say it twice.
"Frogs and Fauns! The tournament!" - Professor Winneynoodle/HanClinto

I reserve the full right to change my views/theories at any time.

quote:

---

Originally posted by Lazarus:
I'm working on a movement system similar to this one - but ran into some problems.
*snip*
Looks fine, right -
Problem is, the object being moved will go off in seemingly random directions - never at the right angle.

---

In what units are you storing your ship's heading? Radians or degrees? Most computer programming languages use radians (where there are 2*pi of them in a circle) as opposed to degrees (where there are 360 of them in a circle).

Here's a decent page that shows how degrees and radians line up.

To convert from degrees to radians, multiply by (pi / 180). That would make your code look like the following:

IF KEY(200) ship1.xVel = ship1.xVel - COS((ship1.heading-90) * 3.14159 / 180) * thrust ship1.yVel = ship1.yVel - SIN((ship1.heading-90) * 3.14159 / 180) * thrust ELSE IF KEY(208) ship1.xVel = ship1.xVel + COS((ship1.heading-90) * 3.14159 / 180) * thrust ship1.yVel = ship1.yVel + SIN((ship1.heading-90) * 3.14159 / 180) * thrust

Give that a whirl, and see how it works for you.

To optimize it, you'd want to remove the division operation, and so the 3.14159 / 180 would turn into just 0.0174533, but I just left it that way so that you could see the theory behind it.

Hope that helps!

--clint

[This message has been edited by HanClinto (edited March 28, 2007).]

Clint, GLBasic uses degrees for the sin-cos-tan functions(a pleasant surprise - most Basics seem to use radians), so that part was working correctly.
I'm noting down your post for future reference, though - I've had alot of headaches with that degrees/radian problem in the past.

Mene, you hit on it - I reversed the sin-cos function calls, and it works perfectly. Sine for Y, Cosine for X. *slaps forehead*
Thanks a million.

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MM out-
Thought travels much faster than sound, it is better to think something twice, and say it once, than to think something once, and have to say it twice.
"Frogs and Fauns! The tournament!" - Professor Winneynoodle/HanClinto

I reserve the full right to change my views/theories at any time.

In this game - which is a Kspaceduel clone - the ship fires bullets(no surprise there).

I worked out firing one bullet at a time - as shown below:
(this is code plucked from various parts of the source)

TYPE bullet xPos yPos xVel yVel heading offscreen ENDTYPE ... GLOBAL bullet1 AS bullet ... DEC bullet1.xPos, bullet1.xVel DEC bullet1.yPos, bullet1.yVel ... LOADSPRITE "ship1/bullet.bmp", ids bullet1.xPos = ship1.xPos+10 bullet1.yPos = ship1.yPos+17 bullet1.heading = ship1.heading bullet1.xVel = SIN(bullet1.heading-90) * 0.5 bullet1.yVel = COS(bullet1.heading-90) * 0.5 ...

I'd like to be able to create another bullet each time the cannon is fired and have it move off in whichever direction, but - seems like I'd have to
make an entire copy of the above parts of the code for each new bullet.