Misc/abrash-black-book
Watch
1
0
Fork
You've already forked abrash-black-book
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Use backtick code blocks for syntax highlighting

Browse source
This commit is contained in:
James Gregory 2013-12-31 11:38:48 +11:00
commit f658bfbb40
203 changed files with 26546 additions and 25801 deletions
Download patch file Download diff file Expand all files Collapse all files

60
61-04.md
View file

@ -50,35 +50,37 @@ point, as shown in Listing 61.1.
**LISTING 61.1 L61\_1.C**
// Given two line endpoints, a point on a plane, and a unit normal
// for the plane, returns the point of intersection of the line
// and the plane in intersectpoint.
#define DOT_PRODUCT(x,y) (x[0]*y[0]+x[1]*y[1]+x[2]*y[2])
void LineIntersectPlane (float *linestart, float *lineend,
float *planeorigin, float *planenormal, float *intersectpoint)
{
float vec1[3], projectedlinelength, startdistfromplane, scale;
vec1[0] = linestart[0] - planeorigin[0];
vec1[1] = linestart[1] - planeorigin[1];
vec1[2] = linestart[2] - planeorigin[2];
startdistfromplane = DOT_PRODUCT(vec1, planenormal);
if (startdistfromplane == 0)
{
// point is in plane
intersectpoint[0] = linestart[0];
intersectpoint[1] = linestart[1];
intersectpoint[2] = linestart[1];
return;
}
vec1[0] = linestart[0] - lineend[0];
vec1[1] = linestart[1] - lineend[1];
vec1[2] = linestart[2] - lineend[2];
projectedlinelength = DOT_PRODUCT(vec1, planenormal);
scale = startdistfromplane / projectedlinelength;
intersectpoint[0] = linestart[0] - vec1[0] * scale;
intersectpoint[1] = linestart[1] - vec1[1] * scale;
intersectpoint[2] = linestart[1] - vec1[2] * scale;
}
```c
// Given two line endpoints, a point on a plane, and a unit normal
// for the plane, returns the point of intersection of the line
// and the plane in intersectpoint.
#define DOT_PRODUCT(x,y) (x[0]*y[0]+x[1]*y[1]+x[2]*y[2])
void LineIntersectPlane (float *linestart, float *lineend,
float *planeorigin, float *planenormal, float *intersectpoint)
{
float vec1[3], projectedlinelength, startdistfromplane, scale;
vec1[0] = linestart[0] - planeorigin[0];
vec1[1] = linestart[1] - planeorigin[1];
vec1[2] = linestart[2] - planeorigin[2];
startdistfromplane = DOT_PRODUCT(vec1, planenormal);
if (startdistfromplane == 0)
{
// point is in plane
intersectpoint[0] = linestart[0];
intersectpoint[1] = linestart[1];
intersectpoint[2] = linestart[1];
return;
}
vec1[0] = linestart[0] - lineend[0];
vec1[1] = linestart[1] - lineend[1];
vec1[2] = linestart[2] - lineend[2];
projectedlinelength = DOT_PRODUCT(vec1, planenormal);
scale = startdistfromplane / projectedlinelength;
intersectpoint[0] = linestart[0] - vec1[0] * scale;
intersectpoint[1] = linestart[1] - vec1[1] * scale;
intersectpoint[2] = linestart[1] - vec1[2] * scale;
}
```
### Rotation by Projection {#Heading10}