From 4e74910bfc091d876c9d2a7e5706be144faee84b Mon Sep 17 00:00:00 2001
From: Vince Weaver <vincent.weaver@maine.edu>
Date: Wed, 25 May 2016 16:27:32 -0400
Subject: [PATCH] ksp: have BASIC physics going

---
 ksp/Makefile       |  5 ++++
 ksp/c/ksp_launch.c | 23 +++++++++++-----
 ksp/physics.bas    | 69 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+), 7 deletions(-)
 create mode 100644 ksp/physics.bas

diff --git a/ksp/Makefile b/ksp/Makefile
index 629aa010..deb12204 100644
--- a/ksp/Makefile
+++ b/ksp/Makefile
@@ -15,6 +15,9 @@ LAUNCH.BAS:	launch.bas
 LOADING.BAS:	loading.bas
 	$(TXT2BAS) < loading.bas > LOADING.BAS
 
+PHYSICS.BAS:	physics.bas
+	$(TXT2BAS) < physics.bas > PHYSICS.BAS
+
 VAB.BAS:	vab.bas
 	$(TXT2BAS) < vab.bas > VAB.BAS
 
@@ -23,6 +26,7 @@ VAB.BAS:	vab.bas
 ksp.dsk:	ACMPLX.BAS \
 		LAUNCH.BAS \
 		LOADING.BAS LOADING.HGR SQUAD.HGR TITLE.HGR \
+		PHYSICS.BAS \
 		VAB.BAS VAB.HGR
 	$(DOS33) -y ksp.dsk SAVE B LOADING.HGR
 	$(DOS33) -y ksp.dsk SAVE B SQUAD.HGR
@@ -32,6 +36,7 @@ ksp.dsk:	ACMPLX.BAS \
 	$(DOS33) -y ksp.dsk SAVE A LOADING.BAS
 	$(DOS33) -y ksp.dsk SAVE A ACMPLX.BAS
 	$(DOS33) -y ksp.dsk SAVE A LAUNCH.BAS
+	$(DOS33) -y ksp.dsk SAVE A PHYSICS.BAS
 
 
 LOADING.HGR:	loading.pcx
diff --git a/ksp/c/ksp_launch.c b/ksp/c/ksp_launch.c
index 987f929c..55805387 100644
--- a/ksp/c/ksp_launch.c
+++ b/ksp/c/ksp_launch.c
@@ -120,9 +120,10 @@ int main(int argc, char **argv) {
 
 	while(1) {
 
+		/* 4010 */
 		fuel_left=fuel_mass*100.0/total_fuel;
 
-		thrusting=autopilot(fuel_left, rocket_altitude,&angle);
+		thrusting=1;//autopilot(fuel_left, rocket_altitude,&angle);
 
 		if (thrusting) {
 			if (fuel_mass<0.1) {
@@ -144,12 +145,15 @@ int main(int argc, char **argv) {
 			rocket_acceleration_y=0.0;
 		}
 
-		if (rocket_y<0) gravity_angle=PI+atan(rocket_x/rocket_y);
-		else gravity_angle=atan(rocket_x/rocket_y);
+		/* 4060 */
+		gravity_angle=atan(rocket_x/rocket_y);
+		if (rocket_y<0) gravity_angle+=PI;
 
+		/* 4070 */
 		gravity_y=cos(gravity_angle)*gravity;
 		gravity_x=sin(gravity_angle)*gravity;
 
+		/* 4080 */
 		rocket_acceleration_y+=gravity_y;
 		rocket_acceleration_x+=gravity_x;
 
@@ -168,6 +172,8 @@ int main(int argc, char **argv) {
 
 		rocket_altitude=vector_magnitude(rocket_x,rocket_y);
 
+		/* 5020 */
+
 		if (rocket_altitude<KERBIN_RADIUS) {
 			if (rocket_velocity<20.0) {
 				printf("LANDED!\n");
@@ -178,6 +184,7 @@ int main(int argc, char **argv) {
 			break;
 		}
 
+		/* 5030 */
 		/* Adjust gravity */
 		gravity=-9.8/(
 			((rocket_altitude)/KERBIN_RADIUS)*
@@ -188,13 +195,14 @@ int main(int argc, char **argv) {
 		htabvtab(1,21);
 
 		printf("Time: %lf\n",time);
-		printf("ALT: %lf m\tg=%lf\n",rocket_altitude-KERBIN_RADIUS,gravity);
+		printf("ALT: %lf km\tg=%lf\n",(rocket_altitude-KERBIN_RADIUS)/1000.0,
+				gravity);
 		printf("VEL: %lf m/s\tStage: %d\n",
 			rocket_velocity,
 			stage);
 		printf("ACCEL: %lf g\tFuel: %lf%%",
 			vector_magnitude(rocket_acceleration_x,rocket_acceleration_y)/9.8,
-			fuel_mass*100.0/total_fuel);
+			fuel_left);
 
 		htabvtab(30,21);
 		printf("ZURGTROYD");
@@ -212,8 +220,9 @@ int main(int argc, char **argv) {
 		printf("x=%lf y=%lf\n",rocket_x,rocket_y);
 
 		htabvtab(20,11);
-		printf("vx=%lf vy=%lf\n",rocket_velocity_x,
-			rocket_velocity_y);
+		printf("vx=%lf vy=%lf ax=%lf ay=%lf\n",
+			rocket_velocity_x,rocket_velocity_y,
+			rocket_acceleration_x,rocket_acceleration_y);
 		htabvtab(20,10);
 		printf("angle=%lf\n",angle);
 
diff --git a/ksp/physics.bas b/ksp/physics.bas
new file mode 100644
index 00000000..54f61dae
--- /dev/null
+++ b/ksp/physics.bas
@@ -0,0 +1,69 @@
+3000 AN=0.785
+3001 CM=1
+3002 E=3
+3003 EI=270
+3004 EM=1.5*E
+3005 ET=168*E
+3006 T=6
+3007 KM=0.5*T
+3008 FM=4.0*T
+3009 TF=FM
+3010 FL=100
+3011 G=-9.8
+3012 GX=0:GY=-9.8:GA=0
+3013 V=0:VX=0:VY=0
+3014 AX=0:AY=0
+3015 KR=600000
+3016 RX=0:RY=KR+10
+3017 RA=KR
+3018 S=1:TH=1:T=0
+3020 TM=EM+KM+FM+CM
+3021 MT=TM-FM
+3022 DV=EI*G*LOG(TM/MT)
+3025 TW=ET/(TM*-G)
+3030 FR=ET/(EI*-G)
+3035 PRINT "DELTAV=";DV
+3040 PRINT "THRUST/WEIGHT=";TW
+3050 PRINT "FUEL FLOW RATE=";FR
+4000 REM
+4010 FL=FM*100/TF
+4020 IF TH<>1 THEN GOTO 4050
+4025 IF FM<0.1 THEN FM=0:AX=0:AY=0:GOTO 4050
+4030 AX=(ET/TM)*SIN(AN)
+4035 AY=(ET/TM)*COS(AN)
+4037 PRINT "ET=";ET;" TM=";TM
+4040 FM=FM-FR
+4045 TM=EM+KM+FM+CM
+4047 GOTO 4060
+4050 REM NOT THRUSTING
+4055 AX=0:AY=0
+4060 GA=ATN(RX/RY)
+4062 PRINT "GA=";GA;" AY=";AY
+4065 IF RY<0 THEN GA=GA+3.14
+4070 GY=COS(GA)*G
+4075 GX=SIN(GA)*G
+4080 AY=AY+GY
+4085 AX=AX+GX
+4090 ZX=VX
+4095 ZY=VY
+5000 VY=ZY+AY
+5005 VX=ZX+AX
+5010 V=SQR(VX*VX+VY*VY)
+5012 RY=RY+0.5*(ZY+VY)
+5014 RX=RX+0.5*(ZX+VX)
+5018 RA=SQR(RX*RX+RY*RY)
+5020 IF RA<KR THEN PRINT "CRASH": END
+5030 G=-9.8/((RA/KR)*(RA/KR))
+5035 PRINT "-------------------------"
+5040 PRINT "TIME: ";T
+5050 PRINT "ALT: ";(RA-KR)/1000;"KM","G ";G
+5060 PRINT "VEL: ";V;"M/S","STAGE: ";S
+5070 PRINT "ACCEL: ","FUEL: ";INT(FL);"%"
+5080 PRINT "GRAVANGLE ";GA*180/3.14
+5090 PRINT "X: ";RX;" Y: ";RY
+5100 PRINT "VX: ";VX;" VY: ";VY
+5110 PRINT "ANGLE: ";AN
+5112 PRINT "AX: ";AX;"AY: ";AY
+5118 T=T+1
+5120 REM GET A$:IF A$="Q" THEN END
+5130 GOTO 4000