1 files changed, 127 insertions, 0 deletions
diff --git a/editor/ppmspread.c b/editor/ppmspread.c
new file mode 100644
index 00000000..569d1266
--- /dev/null
+++ b/editor/ppmspread.c
@@ -0,0 +1,127 @@
+/*********************************************************************/
+/* ppmspread -  randomly displace a PPM's pixels by a certain amount */
+/* Frank Neumann, October 1993                                       */
+/* V1.1 16.11.1993                                                   */
+/*                                                                   */
+/* version history:                                                  */
+/* V1.0 12.10.1993    first version                                  */
+/* V1.1 16.11.1993    Rewritten to be NetPBM.programming conforming  */
+/*********************************************************************/
+
+#include <string.h>
+#include "ppm.h"
+
+/* global variables */
+#ifdef AMIGA
+static char *version = "$VER: ppmspread 1.1 (16.11.93)"; /* Amiga version identification */
+#endif
+
+/**************************/
+/* start of main function */
+/**************************/
+int main(argc, argv)
+int argc;
+char *argv[];
+{
+	FILE* ifp;
+	int argn, rows, cols, i, j;
+	int xdis, ydis, xnew, ynew;
+	pixel **destarray, **srcarray;
+	pixel *pP, *pP2;
+	pixval maxval;
+	pixval r1, g1, b1;
+	int amount;
+	time_t timenow;
+	const char * const usage = "amount [ppmfile]\n        amount: # of pixels to displace a pixel by at most\n";
+
+	/* parse in 'default' parameters */
+	ppm_init(&argc, argv);
+
+	argn = 1;
+
+	/* parse in amount & seed */
+	if (argn == argc)
+		pm_usage(usage);
+	if (sscanf(argv[argn], "%d", &amount) != 1)
+		pm_usage(usage);
+	if (amount < 0)
+		pm_error("amount should be a positive number");
+	++argn;
+
+	/* parse in filename (if present, stdin otherwise) */
+	if (argn != argc)
+	{
+		ifp = pm_openr(argv[argn]);
+		++argn;
+	}
+	else
+		ifp = stdin;
+
+	if (argn != argc)
+		pm_usage(usage);
+
+	/* read entire picture into buffer */
+	srcarray = ppm_readppm(ifp, &cols, &rows, &maxval);
+
+	/* allocate an entire picture buffer for dest picture */
+	destarray = ppm_allocarray(cols, rows);
+
+	/* clear out the buffer */
+	for (i=0; i < rows; i++)
+		memset(destarray[i], 0, cols * sizeof(pixel));
+
+	/* set seed for random number generator */
+	/* get time of day to feed the random number generator */
+	timenow = time(NULL);
+	srand(timenow);
+
+	/* start displacing pixels */
+	for (i = 0; i < rows; i++)
+	{
+		pP = srcarray[i];
+
+		for (j = 0; j < cols; j++)
+		{
+			xdis = (rand() % (amount+1)) - ((amount+1) / 2);
+			ydis = (rand() % (amount+1)) - ((amount+1) / 2);
+
+			xnew = j + xdis;
+			ynew = i + ydis;
+
+			/* only set the displaced pixel if it's within the bounds of the image */
+			if (xnew >= 0 && xnew < cols && ynew >= 0 && ynew < rows)
+			{
+				/* displacing a pixel is accomplished by swapping it with another */
+				/* pixel in its vicinity - so, first store other pixel's RGB      */
+                pP2 = srcarray[ynew] + xnew;
+				r1 = PPM_GETR(*pP2);
+				g1 = PPM_GETG(*pP2);
+				b1 = PPM_GETB(*pP2);
+				/* set second pixel to new value */
+				pP2 = destarray[ynew] + xnew;
+				PPM_ASSIGN(*pP2, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP));
+
+				/* now, set first pixel to (old) value of second */
+				pP2 = destarray[i] + j;
+				PPM_ASSIGN(*pP2, r1, g1, b1);
+			}
+			else
+			{
+                /* displaced pixel is out of bounds; leave the old pixel there */
+                pP2 = destarray[i] + j;
+				PPM_ASSIGN(*pP2, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP));
+			}
+			pP++;
+		}
+	}
+
+	/* write out entire dest picture in one go */
+	ppm_writeppm(stdout, destarray, cols, rows, maxval, 0);
+
+	pm_close(ifp);
+	ppm_freearray(srcarray, rows);
+	ppm_freearray(destarray, rows);
+
+	exit(0);
+}
+