From 73d7f8325aeb00cbaec89a1c15602b9bd85ff04e Mon Sep 17 00:00:00 2001
From: quou <quou@disroot.org>
Date: Fri, 7 Feb 2025 00:34:44 +1100
Subject: collision yes/no

---
 testhull.cpp | 152 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)
 create mode 100644 testhull.cpp

(limited to 'testhull.cpp')

diff --git a/testhull.cpp b/testhull.cpp
new file mode 100644
index 0000000..d02f17a
--- /dev/null
+++ b/testhull.cpp
@@ -0,0 +1,152 @@
+#include <SDL2/SDL.h>
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include "maths.cpp"
+
+struct Shrinkwrap {
+	v2f* points;
+	int count;
+	v2f p0;
+	Shrinkwrap(v2f* src, int src_count):
+		count(0), p0(INFINITY, INFINITY) {
+		int i, top = 0;
+		int stack_size = src_count;
+		v2f* stack = (v2f*)malloc(stack_size * sizeof *stack);
+		points = (v2f*)malloc(src_count * sizeof *points);
+		auto push = [&](v2f p) {
+			assert(top < stack_size);
+			stack[top++] = p;
+		};
+		auto pop = [&]() {
+			assert(top > 0);
+			return stack[--top];
+		};
+		auto peek = [&](int i) {
+			assert(top - 1 - i >= 0);
+			return stack[top - 1 - i];
+		};
+		auto ccw = [](v2f a, v2f b, v2f c) {
+    	float angle =
+    		(b.y - a.y) * (c.x - b.x) -
+    		(b.x - a.x) * (c.y - b.y);
+    	return angle > -0.00001f;
+		};
+		for (i = 0; i < src_count; i++) {
+			v2f p = src[i];
+			if (p.y < p0.y || (fabsf(p.y - p0.y) < 0.0001f && p.x < p0.x))
+				p0 = p;
+		}
+		std::sort(
+			src,
+			src + src_count,
+			[this](const v2f& f, const v2f& s) {
+    		float a =
+    			(f.y - p0.y) * (s.x - f.x) -
+    			(f.x - p0.x) * (s.y - f.y);
+    		bool colinear = fabsf(a - 0.0f) < 0.001f;
+    		if (colinear)
+    			return v2f::mag(p0 - s) >= v2f::mag(p0 - f);
+    		return a < 0.0f;
+			}
+		);
+		for (i = 0; i < src_count; i++) {
+			v2f p = src[i];
+			while (top > 1 && ccw(peek(1), peek(0), p))
+				pop();
+			push(p);
+		}
+		while (top)
+			points[count++] = pop();
+		free(stack);
+	}
+};
+
+int main(int argc, const char** argv) {
+	int r = 1;
+	float rot = 3.5f;
+	SDL_Window* window;
+	SDL_Renderer* ren;
+	SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_JOYSTICK);
+	SDL_CreateWindowAndRenderer(
+		800,
+		800,
+		0,
+		&window,
+		&ren
+	);
+	v2f points[] = {
+		{ 129.0f, 148.0f },
+		{ 178.0f, 178.0f },
+		{ 146.0f, 146.0f },
+		{ 163.0f, 172.0f },
+		{ 129.0f, 159.0f },
+		{ 102.0f, 151.0f },
+		{ 167.0f, 122.0f }
+	};
+	float rots[] = {
+		0.0f,
+		1.0f,
+		1.0f,
+		1.0f,
+		0.0f,
+		1.0f,
+		0.0f,
+	};
+	constexpr int point_count = sizeof points / sizeof *points;
+	v2f points2[point_count];
+	while (r) {
+		int i;
+		SDL_Event e;
+		while (SDL_PollEvent(&e)) {
+			switch (e.type) {
+				case SDL_QUIT:
+					r = 0;
+					break;
+			}
+		}
+		for (i = 0; i < point_count; i++) {
+			v2f p = points[i];
+			points2[i] = v2f(
+				p.x * 2 + (sinf(rot * rots[i]) * p.x - cosf(rot * rots[i]) * p.y),
+				p.y * 2 + (sinf(rot * rots[i]) * p.x + cosf(rot * rots[i]) * p.y)
+			);
+		}
+		Shrinkwrap s(points2, point_count);
+		SDL_SetRenderDrawColor(ren, 0x00, 0x00, 0x00, 0x00);
+		SDL_RenderClear(ren);
+		for (int i = 0; i < s.count; i++) {
+			v2f a = s.points[i];
+			v2f b = s.points[(i + 1) % s.count];
+			v2f e = a - b;
+			v2f h = e * 0.5f;
+			v2f n = v2f(e.y, -e.x);
+			n = v2f::normalised(n);
+			SDL_SetRenderDrawColor(ren, 0x00, 0x00, 0xff, 0xff);
+			SDL_RenderDrawLine(ren, (int)a.x, (int)a.y, (int)b.x, (int)b.y);
+			SDL_SetRenderDrawColor(ren, 0xff, 0x00, 0xff, 0xff);
+			SDL_RenderDrawLine(
+				ren,
+				(int)(a.x - h.x),
+				(int)(a.y - h.y),
+				(int)((a.x - h.x) + n.x * 32.0f),
+				(int)((a.y - h.y) + n.y * 32.0f)
+			);
+		}
+		SDL_SetRenderDrawColor(ren, 0xff, 0x00, 0x00, 0xff);
+		for (i = 0; i < point_count; i++) {
+			v2f p = points2[i];
+			SDL_RenderDrawPoint(ren, (int)p.x, (int)p.y);
+		}
+		SDL_SetRenderDrawColor(ren, 0x00, 0xff, 0x00, 0xff);
+		SDL_RenderDrawPoint(ren, (int)s.p0.x, (int)s.p0.y);
+		SDL_RenderPresent(ren);
+		free(s.points);
+		rot += 0.0003f;
+	}
+	SDL_DestroyRenderer(ren);
+	SDL_DestroyWindow(window);
+	SDL_Quit();
+	return 0;
+}
-- 
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