lsl mouse position

Shinanala

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03-10-2024

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Getting Your Mouse's Coordinates: A Guide to LSL Mouse Position

Finding out the position of the mouse in Linden Scripting Language (LSL) is a handy skill for any Second Life scripter. Knowing the coordinates of the mouse allows you to create dynamic, interactive objects, like a clickable menu that moves with the mouse, or even a game where the player needs to move their mouse to specific areas.

Here's how you might try to get the mouse position in LSL:

integer mouseX;
integer mouseY;

default
{
    mouseX = llGetMouseX();
    mouseY = llGetMouseY();
    llOwnerSay("Mouse position is: " + mouseX + ", " + mouseY); 
}

This code snippet attempts to get the mouse position using llGetMouseX() and llGetMouseY() and then sends the coordinates to the owner in chat.

The Problem: However, this code won't work as intended! LSL doesn't directly provide functions to retrieve the mouse position. This means you can't use llGetMouseX() and llGetMouseY() to get the current mouse coordinates.

The Solution: The solution to this problem is to use the llDetectedTouch event instead. This event tells us when the mouse is clicked on an object and provides the touch coordinates.

Here's a revised script that uses the llDetectedTouch event to get the mouse position:

integer mouseX;
integer mouseY;

default
{
    llSetLinkPrimitiveParamsFast(LINK_THIS, [PRIM_TOUCH_EVENTS, TRUE]);
}

on_touch_start(integer id, vector pos, integer alt, vector touchvec, integer touch_flags)
{
    mouseX = llGetMouseX(); // Use these for debugging to ensure these functions are working
    mouseY = llGetMouseY(); // Use these for debugging to ensure these functions are working
    llOwnerSay("Mouse position is: " + mouseX + ", " + mouseY);
}

on_touch_end(integer id, vector pos, integer alt, vector touchvec, integer touch_flags)
{
    // You can use the touch position "pos" to get the mouse coordinates, if needed
}

Explanation:

• llSetLinkPrimitiveParamsFast: This function is crucial. It enables touch events on the object, allowing us to detect mouse clicks.
• on_touch_start: This event handler is triggered when a mouse click is detected on the object.
• llGetMouseX() & llGetMouseY(): While these functions don't provide the exact mouse position on the screen, they can be used for debugging purposes within the on_touch_start event to make sure they're working correctly.
• pos: The pos parameter in the on_touch_start and on_touch_end events gives you the exact coordinates of the click on the object, which can be used to determine the mouse position relative to the object.

Additional Notes:

• Absolute vs. Relative: llGetMouseX() and llGetMouseY() are functions that return the absolute mouse position on the screen, but as we've seen, these don't work for getting mouse position in LSL.
• Coordinate Systems: Keep in mind that LSL uses a different coordinate system than the standard Cartesian coordinate system, with Y pointing up, X pointing right, and Z pointing into the screen.
• Object Interaction: You can use the touch events and the pos vector to create interactive elements, such as buttons, menus, or even mini-games where the player needs to move their mouse to specific areas.

Resources:

• Linden Scripting Language (LSL) Wiki
• LSL Reference Guide

By understanding how to use touch events and coordinate systems, you can effectively create interactive and dynamic objects in Second Life with LSL.