Computer Science Canada Laser pointer... ish. help please |
| Author: | Mayb123 [ Tue Oct 02, 2007 5:01 pm ] |
| Post subject: | Laser pointer... ish. help please |
i'm trying to make a 2d sidescroller shooter, and i am trying to make a line appear every time you click the mouse which will (so far) extend from coordinates 0 and 0 all the way across the window intercepting with the mouse cursor. so far i can only make it extend to the cursor. help please. here's the code: var key : array char of boolean var reticle : int var mx, my, button, linebasex, linebasey : int var reticlenum : string var weapons :array 1..5 of int setscreen ("graphics:640;480") View.Set ("nomouse") % put "would you like to use reticle one or two?" % get reticlenum % if reticlenum = "one" then % reticle := Pic.FileNew ("Reticle.bmp") % elsif reticlenum = "two" then % reticle := Pic.FileNew ("Reticle2.bmp") % end if loop View.Set ("offscreenonly") Input.KeyDown (key) View.Set ("nomouse") Mouse.Where (mx, my, button) drawfillbox (0, 0, maxx, maxy, 7) % Pic.Draw (reticle, mx - 12, my - 12, picMerge) if button = 1 then drawline (0, 0, mx, my, 12) end if delay (1) View.Update cls end loop |
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| Author: | CodeMonkey2000 [ Tue Oct 02, 2007 5:10 pm ] |
| Post subject: | RE:Laser pointer... ish. help please |
You can take the angle between the mouse and the player, and use some basic trig to extend the line. |
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| Author: | Mayb123 [ Tue Oct 02, 2007 5:21 pm ] |
| Post subject: | Re: Laser pointer... ish. help please |
and how does one incorporate trig into this? |
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| Author: | CodeMonkey2000 [ Tue Oct 02, 2007 5:35 pm ] |
| Post subject: | RE:Laser pointer... ish. help please |
Tan=opposite/adjacent opposite=delta Y adjacent=delta X tan inverse give you the angle if you have opposite/adjacent |
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| Author: | Clayton [ Tue Oct 02, 2007 5:48 pm ] |
| Post subject: | RE:Laser pointer... ish. help please |
Why use trig at all? Why not just use your general equation for a line? y = mx + b? You know your y-intercept is going to be zero, and you can figure out slope, and then solve for x. |
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| Author: | CodeMonkey2000 [ Tue Oct 02, 2007 6:00 pm ] |
| Post subject: | RE:Laser pointer... ish. help please |
Or you could do that. But the advantage with trig is that you can detect obstacles efficiently (ie if there is a ceiling above you, stop the laser). |
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| Author: | Mayb123 [ Tue Oct 02, 2007 6:34 pm ] |
| Post subject: | RE:Laser pointer... ish. help please |
well, my reasoning for this is that i'm going to have a character from which the line will be emitted and that character will be able to run and jump all around the screen (platformer game) and i'm using the mouse as a targeting reticle. so the line will start from the character to the mouse, as i said before |
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| Author: | Mayb123 [ Tue Oct 02, 2007 6:39 pm ] |
| Post subject: | RE:Laser pointer... ish. help please |
oh, and CodeMonkey, thanks for the advice, the only issue is that i don't know where to put that in my code. we were basically given a school project where we have to make a game and learn all the stuff on our own |
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| Author: | CodeMonkey2000 [ Tue Oct 02, 2007 9:23 pm ] |
| Post subject: | RE:Laser pointer... ish. help please |
I think Clayton's method might be better for what you are doing. |
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