[WIP] Katamari: The dark descent (Update 16/11)

[Apjjm]

I figured i'd get in the habit of writing out an occasional update whenever a milestone is met. Also, I finally worked out how to fix AddAttachedPropForProp so that all the parameters are use-able with no loss in precision.

Update as of 24/06/2012

• Re-attachments on resize are now limited, so that only the last 60 or so props are re-attached (this makes a noticeable performance boost when you get to a large size and there were near 300 attachments!)
  
• Made both my attachment list and my world entity list massively more efficient, giving a noticeable reduction in lag when re-attaching props and adding the collision callbacks.
  
• Came up with a full fix for AddAttachedPropToProp which lets all position and rotation parameters be used correctly (the normal function ignores z position and uses z rotation for both position and rotation. Fix is outlined below).
  
• Props are now rotated when they are attached, based on the rotation of the katamari, this makes the whole thing seem a lot more "ball like".
  
• Props should no longer float when attached to the katamari as a side-effect of glancing collisions with very thin/small props.
  
• Started work on a basic particle system when resizing (this is still very much a WIP as it is way too bright) [Thanks palistov for giving me a place to start with the particle editor too]
  

You can see a video of the rotation-based attachment here.

Fixing AddAttachedPropToProp once and for all:

Spoiler below!

This is the function in question from the wiki:

Code: (Select All)

AddAttachedPropToProp(string& asPropName, string& asAttachName, string& asAttachFile, float afPosX, float afPosY, float afPosZ, float afRotX, float afRotY, float afRotZ);

The problem with it: afPosZ is not used for Z position! Rather afRotZ is used for both Z position and ZX rotation.

The initial solution to this problem was to create a new function:

Code: (Select All)

void AttachProp(string& asPropName, string& asAttachName, string& asAttachFile, float afPosX, float afPosY, float afPosZ)
{
  AddAttachedPropToProp(asPropName, asAttachName, asAttachFile, afPosX, afPosY, 0, afPosZ, 90, afPosZ);
}

This let me attach props at the correct position without any Z-rotation, but there was still a rotation in y by 90 degrees, and rotating the attached prop is not possible. To get around this, I made is a 3-stage attachment method, split over two functions. The first function is designed to offset the 90-degree rotation by creating a base prop on which all attachments should be made:

Code: (Select All)

void AddAttachedBaseToProp(string propName, string baseName, string baseFile)
{
   AddAttachedPropToProp(propName,baseName,baseFile,0,0,0,0,-90.0f,0);
}

The second function then assumes you are attaching props to this base:

Code: (Select All)

string AddAttachedPropToBase(string &in asBaseName, string &in asAttachName, string &in asAttachFile, float posX,float posY, float posZ, float angX,float angY,float angZ)
{
        //Generate a unique name for this level
    AddLocalVarInt("DUMMY_ID",1);
    string dummyName1 = "ATTACHMENT_DUMMY_" + GetLocalVarInt("DUMMY_ID");

        //Attach the dummy prop, at the attachment position with cumulative 0,0,0 rotation
    AddAttachPropToProp(asBaseName,dummyName1,"block_box.ent",posZ-angZ,posY,0,-posX,90,-posX);

        //Attach the actual prop with the desired rotation
    AddAttachedPropToProp(dummyName1,asAttachName,asAttachFile,0,0,0,angX,angY,angZ);

        //Return the name of the dummy prop, so that if RemoveAttachedPropFromProp needs to be used,
        //Instead of removing asAttachName, remove the returned dummy name instead to remove the prop.
    return dummyName1;
}

This works, as recall the base has a position of (0,0,0) and rotation of (0,-90,0). For the next attached prop this means that "z" position is now "x" position and (-"x") is now "z". Using this knowledge, the dummy prop is added using the same approach as the initial fix with appropriate swapping of z and x components, and the 90 degree offset already corrected for by the base. Notice that posZ has angZ subtracted from it to offset the translation-by-bug which will be applied in the next step. At the end of the second attachment there is now a dummy prop is at position (posX,posY,posZ-angZ) with rotation (0,0,0).

The desired prop is then attached to the dummy prop at relative positon (0,0,angZ), with the desired rotation, giving a prop attached at (posX,posY,posZ) with angle (angX,angY,angZ).

With the tricky explanation out the way - An example, for attaching a barrel to another barrel:

Code: (Select All)

void someFunction()
{
   //Come up with some name for the base name - can just append "_base" to the end of each prop name.
   string baseName = "barrel01_1_base";
  
   //Create the base (you only need one base per prop)
   AddAttachedBaseToProp("barrel01_1", baseName, "block_box.ent");
  
   //Attach the prop to the base at (1,0,0) with rotation (45,45,45)
   AddAttachedPropToBase(baseName,"barrel01_attachment","barrel01.ent",1,0,0,45,45,45);
}