From 8d834431dfedbdb94d43f8a81fdf5f2d897f89a9 Mon Sep 17 00:00:00 2001
From: Trumeet <yuuta@yuuta.moe>
Date: Thu, 25 Nov 2021 20:11:58 -0800
Subject: feat(tprojvc): first commit

---
 .gitignore |  1 +
 Makefile   |  4 ++-
 README.md  |  2 ++
 tprojvc.c  | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 105 insertions(+), 1 deletion(-)
 create mode 100644 tprojvc.c

diff --git a/.gitignore b/.gitignore
index 41db595..4de0843 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@ a.out
 *.o
 expvc
 expexc
+tprojvc
diff --git a/Makefile b/Makefile
index 99614c1..59d8476 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@ CFLAGS += -I.
 CFLAGS += -std=c99
 CFLAGS += -Wall
 LDLIBS += -lm
-BIN = expvc expexc
+BIN = expvc expexc tprojvc
 
 all: $(BIN)
 
@@ -11,5 +11,7 @@ expvc: expvc.c
 
 expexc: expexc.c
 
+tprojvc: tprojvc.c
+
 clean:
 	rm -rf $(BIN)
diff --git a/README.md b/README.md
index 496cb31..50d54ee 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,8 @@ This repository contains codes for:
 
 * `expexc`: Explosion entity exposure ray casting simulator.
 
+* `tprojvc`: Thrown projectile tracer.
+
 ## Compile
 
 Just `make(1)`. How to build on Windows is left as an exercise to the reader.
diff --git a/tprojvc.c b/tprojvc.c
new file mode 100644
index 0000000..2fc3f53
--- /dev/null
+++ b/tprojvc.c
@@ -0,0 +1,99 @@
+/*
+ * Thrown projectile velocity calculator.
+ *
+ * @1.17.1
+ *
+ */
+#include "common.h"
+
+int main(int argc, char **argv)
+{
+	if (argc <= 1)
+	{
+		goto usage;
+usage:
+		fprintf(stderr, "Usage: %s -p 0,0,0 -v 0,0,0 -t 10 [-w] [-ng]\n"
+				"\n"
+				"Options:\n"
+				"\t-p vec3d\tInitial position [Mandatory]\n"
+				"\t-v vec3d\tInitial velocity [Mandatory]\n"
+				"\t-t int\tTicks to simulate [Mandatory]\n"
+				"\t-w\tIn water [Optional]\n"
+				"\t-ng\tNo gravity [Optional]\n"
+				"\t-h\tShow this help\n"
+				"\n"
+				"Vec3D Format: x,y,z. No spaces or brackets allowed.\n"
+				"Numbers represent post-tick values.\n",
+				argv[0]
+		       );
+		return 64;
+	}
+	struct vec3d v = { VEC3D, 0, 0, 0 };
+	struct vec3d pos = { VEC3D, 0, 0, 0 };
+	int ticks = 0;
+	int water = 0;
+	int no_gravity = 0;
+
+	int r = 0;
+	for (int i = 1; i < argc; i ++)
+	{
+		const char *arg = argv[i];
+                if (!strcmp("-h", arg)) { goto usage; }
+		else if (!strcmp("-w", arg)) { water = 1; continue; }
+		else if (!strcmp("-ng", arg)) { no_gravity = 1; continue; }
+                if (i == argc - 1)
+                {
+                        fprintf(stderr, "%s requires an argument.\n", arg);
+                        goto usage;
+                }
+                char *val = argv[++i];
+		if (!strcmp("-p", arg)) { if ((r = val_parse(val, (struct val *)&pos))) return r; }
+		else if (!strcmp("-v", arg)) { if ((r = val_parse(val, (struct val *)&v))) return r; }
+		else if (!strcmp("-t", arg))
+		{
+			sscanf(val, "%d", &ticks);
+			if (ticks <= 0)
+			{
+				fprintf(stderr, "-t requires a natural number.\n");
+				goto usage;
+			}
+		}
+		else
+                {
+                        fprintf(stderr, "Unknown argument: %s\n", arg);
+                        goto usage;
+                }
+	}
+
+	fprintf(stderr, "t,x,y,z,vx,vy,vz\n");
+	/* Initial value. Print to stderr (classified as verbose msg) */
+	fprintf(stderr, "%d,%.5f,%.5f,%.5f,%.5f,%.5f,%.5f\n",
+			0,
+			pos.x,
+			pos.y,
+			pos.z,
+			v.x,
+			v.y,
+			v.z);
+	const float deaccel = water ? 0.8f : 0.99f;
+	for (int i = 1; i <= ticks; i ++)
+	{
+		pos.x += v.x;
+		pos.y += v.y;
+		pos.z += v.z;
+		v.x *= deaccel;
+		v.y *= deaccel;
+		v.z *= deaccel;
+		v.y -= no_gravity ? 0.0f : 0.03f;
+		printf("%d,%.5f,%.5f,%.5f,%.5f,%.5f,%.5f\n",
+				i,
+				pos.x,
+				pos.y,
+				pos.z,
+				v.x,
+				v.y,
+				v.z);
+	}
+	return 0;
+}
+
-- 
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