Find the intersection of a line with a plane: Difference between revisions

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=={{header|Action!}}==

{{libheader|Action! Tool Kit}}

<lang Action!>INCLUDE "D2:REAL.ACT" ;from the Action! Tool Kit

TYPE VectorR=[CARD x,y,z] ;REAL POINTER

PROC PrintVector(VectorR POINTER v)

Print("(") PrintR(v.x)

Print(",") PrintR(v.y)

Print(",") PrintR(v.z)

Print(")")

RETURN

PROC Vector(REAL POINTER vx,vy,vz VectorR POINTER v)

v.x=vx v.y=vy v.z=vz

RETURN

PROC VectorSub(VectorR POINTER a,b,res)

RealSub(a.x,b.x,res.x)

RealSub(a.y,b.y,res.y)

RealSub(a.z,b.z,res.z)

RETURN

PROC VectorDot(VectorR POINTER a,b REAL POINTER res)

REAL tmp1,tmp2

RealMult(a.x,b.x,res)

RealMult(a.y,b.y,tmp1)

RealAdd(res,tmp1,tmp2)

RealMult(a.z,b.z,tmp1)

RealAdd(tmp1,tmp2,res)

RETURN

PROC VectorMul(VectorR POINTER a REAL POINTER b VectorR POINTER res)

RealMult(a.x,b,res.x)

RealMult(a.y,b,res.y)

RealMult(a.z,b,res.z)

RETURN

BYTE FUNC IsZero(REAL POINTER a)

CHAR ARRAY s(10)

StrR(a,s)

IF s(0)=1 AND s(1)='0 THEN

RETURN (1)

FI

RETURN (0)

BYTE FUNC Intersection(VectorR POINTER

rayVector,rayPoint,planeNormal,planePoint,result)

REAL tmpx,tmpy,tmpz,prod1,prod2,prod3

VectorR tmp

Vector(tmpx,tmpy,tmpz,tmp)

VectorSub(rayPoint,planePoint,tmp)

VectorDot(tmp,planeNormal,prod1)

VectorDot(rayVector,planeNormal,prod2)

IF IsZero(prod2) THEN

RETURN (1)

FI

RealDiv(prod1,prod2,prod3)

VectorMul(rayVector,prod3,tmp)

VectorSub(rayPoint,tmp,result)

RETURN (0)

PROC Test(VectorR POINTER rayVector,rayPoint,planeNormal,planePoint)

BYTE res

REAL px,py,pz

VectorR p

Vector(px,py,pz,p)

res=Intersection(rayVector,rayPoint,planeNormal,planePoint,p)

Print("Ray vector: ")

PrintVector(rayVector) PutE()

Print("Ray point: ")

PrintVector(rayPoint) PutE()

Print("Plane normal: ")

PrintVector(planeNormal) PutE()

Print("Plane point: ")

PrintVector(planePoint) PutE()

IF res=0 THEN

Print("Intersection point: ")

PrintVector(p) PutE()

ELSEIF res=1 THEN

PrintE("There is no intersection")

FI

PutE()

RETURN

PROC Main()

REAL r0,r1,r5,r10,rm1

VectorR rayVector,rayPoint,planeNormal,planePoint

Put(125) PutE() ;clear screen

ValR("0",r0) ValR("1",r1) ValR("5",r5)

ValR("10",r10) ValR("-1",rm1)

Vector(r0,rm1,rm1,rayVector)

Vector(r0,r0,r10,rayPoint)

Vector(r0,r0,r1,planeNormal)

Vector(r0,r0,r5,planePoint)

Test(rayVector,rayPoint,planeNormal,planePoint)

Vector(r1,r1,r0,rayVector)

Vector(r1,r1,r0,rayPoint)

Vector(r0,r0,r1,planeNormal)

Vector(r5,r1,r0,planePoint)

Test(rayVector,rayPoint,planeNormal,planePoint)

RETURN</lang>

{{out}}

[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Find_the_intersection_of_a_line_with_a_plane.png Screenshot from Atari 8-bit computer]

<pre>

Ray vector: (0,-1,-1)

Ray point: (0,0,10)

Plane normal: (0,0,1)

Plane point: (0,0,5)

Intersection point: (0,-5,5)

Ray vector: (1,1,0)

Ray point: (1,1,0)

Plane normal: (0,0,1)

Plane point: (5,1,0)

There is no intersection