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A question for those more mathematically inclined than myself:

I am displaying a CSM map in my program, in the style of an RTS game. Looks sort of like Syndicate. The player can scroll the view around, looking down on the map birds-eye style. I have a mouse pointer that the player uses to select objects and issue commands to them.

Now, I need an equation to convert the position of the mouse on the screen into 3D coordinates, taking into account the floating camera location and different floor-heights around the map. To express this another way, if the mouse pointer were to simply 'become' a 3D object and 'fall' straight downward in 3D space toward the floor, I need a formula to obtain the coordinates of the spot the pointer impacts the floor.

I will need all three coordinates.

If it makes it easier to understand, I will be calling this formula when the mouse is clicked, and comparing the coordinates returned by the formula with the coordinates of all active objects to determine which one was clicked on. This would be a simple matter if the camera never moved, but taking into account that the camera could be anywhere (camera X and Z coordinates change as the player scrolls the view around RTS style, Z coordinate changes as the player zooms the view in and out) makes this a far more complex mathematical situation.

I know this whole concept is a difficult one to understand in writing, so the simplest way I can put it is if I had a top down RTS game with a camera that scrolls around the map like all RTS's, I need to determine the coordinates on the map the player has clicked, to compare those coordinates with the coordinates of the tanks on the map to determine which tank the player has selected.

Is anybody able to tackle this formula?

Yes, there is RTS location code in my Vector Guide. Go and read that. The website http was given in the latest TGC newsletter.

Philip

tisk, tisk, Bear - thats twice


Agent, this is the link that lazy bear referred to:
http://www.kentaree-studios.com/tutorials/vectors/

lol

Bears are naturally lazy. He can't help it.

for other ideas on how to do other parts in the rts, skim through my rts barebone demo in the code snippets board.

Yes, Phaelax's tutorial is excellent.

Incidentally, I actually deliberately don't quote the http of the Guide. This is because I know Cattle does it for me. LOL

Philip

its not really a tutorial. its more like a big chunk of uncommented code. I should write a detailed tutorial though, and perhaps actually finish the game.

Uncommented code scares me. You have to spend 50% of your time working out what on earth is going on.

Philip