gr-sim: work on better plasma

utils/gr-sim/plasma/Makefile

@@ -6,7 +6,7 @@ SDL_LIBS= `sdl-config --libs`
 SDL_INCLUDE= `sdl-config --cflags`
 GR_SIM = ../gr-sim.a
 
-all:	plasma plasma_fixed
+all:	plasma plasma_fixed plasma_new
 
 ###
 
@@ -19,6 +19,16 @@ plasma.o:	plasma.c
 
 ###
 
+plasma_new:	plasma_new.o $(GR_SIM)
+	$(CC) -o plasma_new plasma_new.o \
+		$(GR_SIM) $(LFLAGS) $(SDL_LIBS)
+
+plasma_new.o:	plasma_new.c
+	$(CC) $(CFLAGS) -c plasma_new.c
+
+
+###
+
 plasma_fixed:	plasma_fixed.o $(GR_SIM)
 	$(CC) -o plasma_fixed plasma_fixed.o \
 		$(GR_SIM) $(LFLAGS) $(SDL_LIBS)

utils/gr-sim/plasma/plasma_new.c

@@ -0,0 +1,110 @@
+/* for demoscene, you need a plasma effect... */
+/* https://rosettacode.org/wiki/Plasma_effect */
+/* https://www.bidouille.org/prog/plasma */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <math.h>
+
+#include "tfv_zp.h"
+#include "gr-sim.h"
+
+#define PI 3.14159265358979323846264338327950
+
+
+#if 1
+static unsigned char color_lookup[]={0x0, 0x0, 0x5, 0x5,
+				     0x7, 0x7, 0xf, 0xf,
+				     0x7, 0x7, 0x6, 0x6,
+				     0x2, 0x2, 0x5, 0x5};
+#else
+
+static unsigned char color_lookup[]={0x0, 0x5, 0x7, 0xf,
+				     0x7, 0x6, 0x2, 0x5,
+				     0x0, 0x5, 0x7, 0xf,
+				     0x7, 0x6, 0x2, 0x5};
+
+#endif
+
+static int offscreen[40][40];
+
+int main(int argc, char **argv) {
+
+	int ch,xx,yy,col;
+
+	grsim_init();
+
+	gr();
+	soft_switch(MIXCLR);
+
+	clear_screens();
+
+	ram[DRAW_PAGE]=0x0;
+
+	for(yy=0;yy<40;yy++) {
+	for(xx=0;xx<40;xx++) {
+
+//	col = ( 32.0 + (32.0 * sin(xx / 4.0))
+  //            + 32.0 + (32.0 * sin(yy / 4.0))
+    //          ) / 2;
+
+
+//	col = ( 8.0 + (8.0 * sin(xx *PI/8.0))
+  //            + 8.0 + (8.0 * sin(yy *PI/8.0))
+    //          ) / 2;
+
+#if 0
+ 	col = (int)
+    (
+        128.0 + (128.0 * sin(xx / 16.0))
+      + 128.0 + (128.0 * sin(yy / 8.0))
+      + 128.0 + (128.0 * sin((xx + yy) / 16.0))
+      + 128.0 + (128.0 * sin(sqrt( (double)(xx * xx + yy * yy)) / 8.0))
+    ) / 4;
+#else
+ 	col = (int)
+    ((
+        4.0 + sin(xx / 16.0)
+          + sin(yy / 8.0)
+          + sin((xx + yy) / 16.0)
+         // + sin(sqrt(xx * xx + yy * yy) / 8.0)
+    )*32) ;
+
+	printf("%d %d %d\n",xx,yy,col);
+#endif
+
+
+			offscreen[xx][yy]=col;
+		}
+	}
+
+	while(1) {
+		for(yy=0;yy<40;yy++) {
+			for(xx=0;xx<40;xx++) {
+				col=offscreen[xx][yy];
+				color_equals(color_lookup[col]);
+				col++;
+				col&=0xf;
+				offscreen[xx][yy]=col;
+				plot(xx,yy);
+			}
+		}
+
+		grsim_update();
+
+		ch=grsim_input();
+		if (ch=='q') exit(0);
+
+		if (ch==' ') {
+			while(1) {
+				ch=grsim_input();
+				if (ch) break;
+			}
+		}
+		usleep(200000);
+	}
+
+
+	return 0;
+}