absobj.cpp File Reference

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Detailed Description

Implementation of AbsObj class.

#include <GL/gl.h>
#include <iostream>
#include <vector>
#include "absobj.h"
#include "maths.h"

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Functions
int	getside (float *in)
	Given a set of floats, identifies the single one on the wrong side of 0 (where wrong is arbitrary).
Vec4	getintersect (float &fin1, float &fin2, Vec4 &in1, Vec4 &in2)
	This finds the intersection of a line with a plane.
bool	inTriangle (Vec4 p, Vec4 p0, Vec4 p1, Vec4 p2)
	Given a point p, and a triangle p0,p1,p2, calculate if p is within the triangle.
bool	inflattriangle (float x1, float y1, float x2, float y2, float x3, float y3, float px, float py)
	Find if a point is in a 2D triangle.
int	collideResponse (float time, AbsObj &bill, AbsObj &ben, Vec4 &pt, Vec4 &n, Vec4 &intr, float sticky)
	Collision response.

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Function Documentation

int collideResponse (  float  time, AbsObj &  bill, AbsObj &  ben, Vec4 &  pt, Vec4 &  n, Vec4 &  intr, float  sticky )

Collision response. Important rigid-body physics. This does lots of important collision response for all objects. Todo: Write this in more depth. Parameters: time  The length of time of the collision. bill  One of the colliding objects. ben  The other object. pt  Point of collision (in world space). n  Normal of collision. intr  Intersection of the objects. sticky  The elasticity coefficient. Between 0 and 1. Returns: 0. Return value not used atm. Todo: Fix intersection code. While the code itself is correct, the way in which we find the intersection distance is not correct. See also: AbsObj::collide.

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Vec4 getintersect (  float &  fin1, float &  fin2, Vec4 &  in1, Vec4 &  in2 )

This finds the intersection of a line with a plane. I have NO IDEA how. Parameters: fin1  The result of putting in1 into a plane equation. fin2  The result of putting in2 into a plane equation. in1  A point. in2  Another point. Returns: The point on the plane.

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int getside (  float *  in  )

Given a set of floats, identifies the single one on the wrong side of 0 (where wrong is arbitrary). This is a very bizarre function, that I'm quite proud of. It creates a bitmask corresponding to whether an entry in the array is greater than 0 (or not). As we don't care which side is which, as long as one is different from the other two, it negates 4-7 down to 0-3. Returns: An integer from 0-4. 0 means the array does not swap sides. Subtract 1 otherwise.

bool inflattriangle (  float  x1, float  y1, float  x2, float  y2, float  x3, float  y3, float  px, float  py )

Find if a point is in a 2D triangle. This takes three pairs of floats as the triangle, and the fourth pair as the point. I made a pretty test-harness that used it to draw triangles, so it should work.

bool inTriangle (  Vec4  p, Vec4  p0, Vec4  p1, Vec4  p2 )

Given a point p, and a triangle p0,p1,p2, calculate if p is within the triangle. All points are assumed to be coplanar. Parameters: p  The point of unknown placement. p0  First point of triangle. p1  Second point. p2  Third. Returns: True if point is within triangle. Todo: remove calculation of normal.

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