drops: seeing if possible

utils/gr-sim/Makefile

@@ -9,6 +9,7 @@ SDL_INCLUDE= `sdl-config --cflags`
 all:	gr-sim.a
 	make -C 6502_test
 	make -C dos
+	make -C drops
 	make -C fade
 	make -C fire
 #	make -C fluid
@@ -58,6 +59,7 @@ clean:
 	rm -f *~ *.o *.a
 	make -C 6502_test clean
 	make -C dos clean
+	make -C drops clean
 	make -C fade clean
 	make -C fire clean
 	make -C fluid clean

utils/gr-sim/drops/Makefile

@@ -0,0 +1,17 @@
+CC = gcc
+CFLAGS = -O2 -Wall -I.. -g
+
+SDL_LIBS= `sdl-config --libs`
+SDL_INCLUDE= `sdl-config --cflags`
+GR_SIM = ../gr-sim.a
+
+all:	drops
+
+drops: drops.o
+	$(CC) $(LFLAGS) -o drops drops.o $(GR_SIM) $(SDL_LIBS)
+
+drops.o:	drops.c
+	$(CC) $(CFLAGS) -c drops.c
+
+clean:	
+	rm -f *~ *.o drops

utils/gr-sim/drops/README

@@ -0,0 +1,4 @@
+raindrop type visualization
+
+Roughly based on this code by Seban/Slight
+https://github.com/seban-slt/Atari8BitBot/blob/master/ASM/water/water.m65

utils/gr-sim/drops/drops.c

@@ -0,0 +1,157 @@
+/* Based on https://twitter.com/seban_slt/status/1349084515755548676
+   https://github.com/seban-slt/Atari8BitBot/blob/master/ASM/water/water.m65 */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "gr-sim.h"
+#include "tfv_zp.h"
+
+#define XSIZE	40
+#define YSIZE	48
+
+static unsigned char buffer1[XSIZE*YSIZE];
+static unsigned char buffer2[XSIZE*YSIZE];
+static unsigned int frame=0;
+
+
+static void update_frame2(void) {
+	int xx,yy,temp;
+
+	for(yy=0;yy<YSIZE;yy++) {
+		for(xx=0;xx<XSIZE;xx++) {
+			temp=0;
+			if (yy>0) temp+=buffer1[(yy-1)*XSIZE+xx];
+			if (yy<YSIZE-1) temp+=buffer1[(yy+1)*XSIZE+xx];
+			if (xx>0) temp+=buffer1[yy*XSIZE+xx-1];
+			if (xx<XSIZE-1) temp+=buffer1[yy*XSIZE+xx+1];
+			temp/=2;
+			temp-=buffer2[yy*XSIZE+xx];
+			if (temp<0) temp=-temp;
+			buffer2[yy*XSIZE+xx]=temp;
+		}
+	}
+	return;
+
+}
+
+static void update_frame1(void) {
+	int xx,yy,temp;
+
+	for(yy=0;yy<YSIZE;yy++) {
+		for(xx=0;xx<XSIZE;xx++) {
+			temp=0;
+			if (yy>0) temp+=buffer2[(yy-1)*XSIZE+xx];
+			if (yy<YSIZE-1) temp+=buffer2[(yy+1)*XSIZE+xx];
+			if (xx>0) temp+=buffer2[yy*XSIZE+xx-1];
+			if (xx<XSIZE-1) temp+=buffer2[yy*XSIZE+xx+1];
+			temp/=2;
+			temp-=buffer1[yy*XSIZE+xx];
+			if (temp<0) temp=-temp;
+			buffer1[yy*XSIZE+xx]=temp;
+		}
+	}
+	return;
+
+}
+
+static void plot_frame1(void) {
+
+	int xx,yy,c;
+
+	for(yy=0;yy<YSIZE;yy++) {
+		for(xx=0;xx<XSIZE;xx++) {
+			c=buffer1[yy*XSIZE+xx];
+			c/=2;
+			if (c==0) c=0;
+			else if (c==1) c=2;
+			else if (c==2) c=6;
+			else if (c==3) c=14;
+			else if (c==4) c=7;
+			else c=15;
+			color_equals(c);
+			plot(xx,yy);
+		}
+	}
+}
+
+static void plot_frame2(void) {
+
+	int xx,yy,c;
+
+	for(yy=0;yy<YSIZE;yy++) {
+		for(xx=0;xx<XSIZE;xx++) {
+			c=buffer1[yy*XSIZE+xx];
+			c/=2;
+			if (c==0) c=0;
+			else if (c==1) c=2;
+			else if (c==2) c=6;
+			else if (c==3) c=14;
+			else if (c==4) c=7;
+			else c=15;
+			color_equals(c);
+			plot(xx,yy);
+		}
+	}
+}
+
+
+
+int main(int argc, char **argv) {
+
+	int xx,yy;
+	int ch;
+
+	grsim_init();
+
+	gr();
+
+	clear_screens();
+
+	ram[DRAW_PAGE]=0;
+
+	frame=0;
+
+	while(1) {
+
+		if (frame&1) {
+			update_frame1();
+			plot_frame1();
+		}
+		else {
+			update_frame2();
+			plot_frame2();
+		}
+
+		if ((frame&0x1f)==0) {
+
+			xx=rand()%XSIZE;
+			yy=rand()%YSIZE;
+
+			if (xx==0) xx++;
+			if (yy==0) yy++;
+			if (xx>XSIZE-1) xx--;
+			if (yy>YSIZE-1) yy--;
+
+
+			buffer1[yy*XSIZE+xx]=0x1f;
+			buffer1[yy*XSIZE+xx+1]=0x1f;
+			buffer1[yy*XSIZE+xx-1]=0x1f;
+			buffer1[(yy+1)*XSIZE+xx]=0x1f;
+			buffer1[(yy-1)*XSIZE+xx]=0x1f;
+
+		}
+
+		grsim_update();
+
+		usleep(60000);
+		frame++;
+
+		ch=grsim_input();
+		if (ch=='q') return 0;
+		if (ch==27) return 0;
+	}
+
+	return 0;
+}