KCL files

Introduction

KCL files are the ones that control solidity in a course.
If the KCL file is wrong, you can fall trough the ground or drive through the walls.

Header

The first block is the begin of the values. In the most kcl files is it 3C.
The third block is the start of the ground ID Section.
It is little endian so: D8 5F 00 00 = 00 00 5F D8.
Now: 00005FD8+F=00005FE8

And there are the begin of the ground ID section.

Offset	Type	Description
0x00	u32	Offset to section 1
0x04	u32	Offset to section 2
0x08	u32	Offset to section 3
0x0c	u32	Offset to section 4
0x10	single	Unknown
0x14	single3	Spatial grid first coordinate
0x20	u32	X mask
0x24	u32	Y mask
0x28	u32	Z mask
0x2c	u32	Coordinate shift
0x30	u32	Y shift
0x34	u32	Z shift
0x38	single	Unknown

The Vertex section

A positon is the same as in a nkm file, but it is only the x,y,z coordinates. It is also little endian. The most times the first position is starting on: "00 00 00 3C"

Bytes	What	Comments
4	X	X position.
4	Y	Y position.
4	Z	Z position.

The Normal section

Quote from wikipedia: http://en.wikipedia.org/wiki/Surface_normal

A surface normal, or simply normal, to a flat surface is a vector that is perpendicular to that surface.
A normal to a non-flat surface at a point P on the surface is a vector perpendicular to the tangent plane to that surface at P.
The word "normal" is also used as an adjective: a line normal to a plane, the normal component of a force, the normal vector, etc.
The concept of normality generalizes to orthogonality.
 
In the two-dimensional case, a normal line perpendicularly intersects the tangent line to a curve at a given point.
 
The normal is often used in computer graphics to determine a surface's orientation toward a light source for flat shading, or the
orientation of each of the corners (vertices) to mimic a curved surface with Phong shading.

Bytes	What	Comments
2	X	X position.
2	Y	Y position.
2	Z	Z position.

The Planar section

Each ground ID is using 10 bytes as you can seen(the yellow marked bytes):

Bytes	What	Comments
4	Length	?
2	Vertex Index	Index in the Vertex section.
2	Normal Index	Index in the Normal section.
2	Normal A Index	Index in the Normal section.
2	Normal B Index	Index in the Normal section.
2	Normal C Index	Index in the Normal section.
2	Collision Type	For Groundtypes look at the KCL ID List.

The Octree section

Quote from wikipedia: http://en.wikipedia.org/wiki/Octree

An octree is a tree data structure in which each internal node has exactly eight children.
Octrees are most often used to partition a three dimensional space by recursively subdividing it into eight octants.
Octrees are the three-dimensional analog of quadtrees.
The name is formed from oct + tree, and normally written "octree", not "octtree".

The octree divide the 3d space in cubes and then it assign the triangles to the cubes.

The working is simple. Mario Kart looks in which cube you are, then which planes collide and then it works.