CODEWITHSUNDEEP
javamousecoordinatesslick2d
Corey
Corey

Reputation: 73

Java Slick2d - How to translate mouse coordinates to world coordinates

I am translating in my main class' render. How do I get the mouse position based on the translation?

public void render(GameContainer gc, Graphics g) 
        throws SlickException 
{
    float centerX = 800/2;
    float centerY = 600/2;
    g.translate(centerX, centerY);
    g.translate(-player.playerX, -player.playerY);
    gen.render(g);
    player.render(g);
}

playerX = 800 /2 - sprite.getWidth();
playerY = 600 /2 - sprite.getHeight();

I update the player position on keydown by .2f * delta

Picture to help with explanation

i92.photobucket.com/albums/l22/occ31191/Untitled-4.png

Upvotes: 0

Views: 1401

Answers (2)

jefflunt
jefflunt

Reputation: 33954

World coordinates = camera position + mouse position

Camera position is calculated/explained in my answer to this question: Slick2D and JBox2D. How to draw

Upvotes: 2

Stefan Hanke
Stefan Hanke

Reputation: 3518

You're making a tile-based game, where each tile seems to have the same size. For this case, you don't need a generalized unprojection.

Imagine the complete map. The viewport shows only a portion of it; somewhere you need to store the (x,y) offets of the viewport into the complete map. Since the mouse coordinates are relative to the viewport, you need to add this offset to the mouse coordinates. Now, you can easily get the tile coordinates by using modulo operations on the shifted mouse coordinates with the tile's width and height.

Effectively, this is a coordinate transformation of window coordinates to tile coordinates.

Upvotes: 1

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