I am following WildBunny's tutorial regarding a simple physics engine :
http://www.wildbunny...es-for-dummies/
However, I have some trouble understanding this part :
"
for all particles i
{
for all planes j
{
distance = P.x*Planes[j].a + P.y*Planes[j].b + Planes[j].c;
if (distance < 0)
{
// collision responce
}
}
}What this code is doing is finding, by projection, how much of the [color=#ff0000]vector from the plane to the particle is in the direction of the plane normal."
If every particle is determined by its (x,y) point, isn't this a vector from the origin to that point ?
This line :
"distance = P.x*Planes[j].a + P.y*Planes[j].b + Planes[j].c"
doesnt actually compute the dot product of the origin-point vector and plane normal rather than the plane-point(vector) and normal dot-product?
I drew some sketches so you can see my point.I am testing a particle against the plane who's normal isnt normalized .
[Sorry, I actually mean dot-product , not cross ] .
I know there's a flaw in my reasoning, but I dont seem to get it .
