Legacy ImageMagick Discussions Archive

Code: Select all

set seg1=-draw "stroke White fill None bezier 0,4000 0,0 400,2800 800,3200"
set seg2=-draw "stroke White fill None bezier 800,3200 1600,4000 3999,1600 3999,0"

set curve=%seg1% %seg2%

set SQDIM=4000

rem Create curveL.tiff, just so we can see the curve.
rem
"%IMG%convert" ^
    -size %SQDIM%x%SQDIM% xc:Black ^
    +antialias ^
    %curve% ^
    curveL.tiff


rem Create one-dimensional curveClut.tiff, to be used as a clut file.
rem
"%IMG%convert" ^
  -size %SQDIM%x%SQDIM% gradient: ^
  ( -size %SQDIM%x%SQDIM% xc:Black ^
    +antialias ^
    %curve% ^
    -alpha off ^
  ) ^
  -compose CopyOpacity -composite ^
  -resize "%SQDIM%x1^!" ^
  -alpha off ^
  curveClut.tiff

"%IMG%identify" curveClut.tiff

"%IMG%convert" ^
  rose: ^
  curveClut.tiff ^
  -clut ^
  roseClutted.tiff

Code: Select all

typedef struct {
  float x;
  float y;
  BOOL HasAng;
  float ang;
  float xOut, yOut, xIn, yIn; // Control points.
} PointT;

#define NUM_POINTS 100
static PointT Points[NUM_POINTS];
static int nPoints = 0;

{blah blah}

static void CalcPoints (void)
{
  // y-coords have been flipped so y=0 is top.

  int i;
  for (i = 0; i < nPoints-1; i++) {
    PointT p0 = Points[i];
    PointT p1 = Points[i+1];
    printf ("x=%g y=%g a=%g  ", p0.x, p0.y, p0.ang);
    printf ("x=%g y=%g a=%g\n", p1.x, p1.y, p1.ang);
    float dx = p1.x - p0.x;
    float dy = p1.y - p0.y;
    float dist = sqrt (dx*dx + dy*dy) / 3;
    printf ("dist=%g\n", dist);

    // Calculate control points: exit for p0 and entry for p1.
    //
    float a0 = p0.ang * M_PI / 180;
    p0.xOut = p0.x + dist * sin(a0);
    p0.yOut = p0.y - dist * cos(a0);
    float a1 = p1.ang * M_PI / 180;
    p1.xIn = p1.x - dist * sin(a1);
    p1.yIn = p1.y + dist * cos(a1);
    printf ("Controls: %g %g  %g %g\n", p0.xOut, p0.yOut, p1.xIn, p1.yIn);

    // If any controls are outside 0..1, we should clip the lines,
    // to ensure the curve stays within bounds.
    //
    // This cheap and cheerful method will generally change the gradient:

    BOOL c = FALSE;

    if      (p0.xOut < 0) {p0.xOut = 0; c = TRUE;}
    else if (p0.xOut > 1) {p0.xOut = 1; c = TRUE;}

    if      (p0.yOut < 0) {p0.yOut = 0; c = TRUE;}
    else if (p0.yOut > 1) {p0.yOut = 1; c = TRUE;}

    if      (p1.xIn  < 0) {p1.xIn = 0; c = TRUE;}
    else if (p1.xIn  > 1) {p1.xIn = 1; c = TRUE;}

    if      (p1.yIn  < 0) {p1.yIn = 0; c = TRUE;}
    else if (p1.yIn  > 1) {p1.yIn = 1; c = TRUE;}

    if (c) WarningError ("One or more control points were clipped.");
    
    Points[i]   = p0;
    Points[i+1] = p1;
  }
}