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C Library Functions  - draw2 (3)

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NAME

draw2(3f) - [M_pixel:DRAW] draw from current position to given point (LICENSE:PD)

CONTENTS

Synopsis
Description
Options
Examples
Author
License

SYNOPSIS

definition:

   elemental impure subroutine draw2(x, y)
   real,intent(in) :: x, y

DESCRIPTION

Draw from current position to specified point using current color and line width. Updates current position to new point. (x, y) is a point in world coordinates.

OPTIONS

X	new X position
Y	new Y position

EXAMPLES

Sample program:

   program demo_draw2
   use M_pixel,    only : prefsize, vinit, ortho2, clear
   use M_pixel,    only : move2, draw2, vexit, color,linewidth
   use M_pixel,    only : P_pixel, P_colormap
   use M_pixel__writegif, only : writegif
   use M_pixel,    only : d2r, polar_to_cartesian
   !
   ! The Archimedean spiral is the locus of points corresponding
   ! to the locations over time of a point moving away from a
   ! fixed point with a constant speed along a line which rotates
   ! with constant angular velocity.
   !    r=A+B*theta
   ! Changing the parameter A will turn the spiral,
   ! while B controls the distance between successive turnings.
   !
   implicit none
   integer        :: i
   real           :: x,y,radius,theta
   real,parameter :: rotate=0.0, gap=2.0
      call prefsize(400,400)
      call vinit(’’)
      call ortho2(-150.0,150.0,-150.0,150.0)
      call color(5)
      call clear()
      call move2(0.0,0.0)
      call color(0)
      call linewidth(40)
      do i=0,360*10,5
         theta=d2r(i)
         ! equation in polar coordinates
         radius=rotate+gap*theta
         ! convert polar coordinates to cartesian
         call polar_to_cartesian(radius,theta,x,y)
         ! draw from current position to end of next segment
         call draw2(x,y)
      enddo
      ! write the pixel map array as a GIF image file
      call writegif(’draw2.3m_pixel.gif’,P_pixel,P_colormap)
      ! exit graphics mode
      call vexit()
   end program demo_draw2

AUTHOR

John S. Urban

LICENSE

Public Domain

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Nemo Release 3.1

draw2 (3)

June 29, 2025

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