From cc05fdc7396532b329f30decde5583853da92a44 Mon Sep 17 00:00:00 2001
From: Matthew Kosarek <mattkae@protonmail.com>
Date: Sat, 27 Mar 2021 20:54:27 -0400
Subject: Drawing an ellipse

---
 frontend/2d/_collisions/pill_line/dist/output.wasm | Bin 27360 -> 37565 bytes
 frontend/2d/_collisions/pill_line/main.cpp         |  85 +++++++++++++++++----
 2 files changed, 71 insertions(+), 14 deletions(-)

(limited to 'frontend/2d')

diff --git a/frontend/2d/_collisions/pill_line/dist/output.wasm b/frontend/2d/_collisions/pill_line/dist/output.wasm
index be1afc5..92ee1f2 100755
Binary files a/frontend/2d/_collisions/pill_line/dist/output.wasm and b/frontend/2d/_collisions/pill_line/dist/output.wasm differ
diff --git a/frontend/2d/_collisions/pill_line/main.cpp b/frontend/2d/_collisions/pill_line/main.cpp
index 321a4ba..df20fa0 100644
--- a/frontend/2d/_collisions/pill_line/main.cpp
+++ b/frontend/2d/_collisions/pill_line/main.cpp
@@ -7,16 +7,70 @@
 #include <emscripten/html5.h>
 #include <unistd.h>
 #include <pthread.h>
+#include <cmath>
 
-typedef OrthographicShape<3> TriangleShape;
+//
+// Pill object 
+//
+struct Pill {
+	OrthographicShape shape;
+	float32 width = 1.f;
+	float32 height = 1.f;
+
+	void load(OrthographicRenderer* renderer, float32 numSegments) {
+		// Note that a so-called "pill" is simply an ellipse.
+		// Equation of an ellipse is:
+		//
+		//	x^2 / a^2 + y^2 / b^2 = 1
+		//
+		// or, in parametric form:
+		//
+		// x = a * cos(t), y = b * sin(t)
+		//
+		float32 angleIncrements = (2.f * PI) / numSegments;
+		uint32 numVertices = static_cast<uint32>(numSegments * 3.f);
+		OrthographicVertex* vertices = new OrthographicVertex[numVertices];
+
+		float32 a = width / 2.f;
+		float32 b = height / 2.f;
+
+		Vector4 color = Vector4().fromColor(243,166,207, 255);
+
+		for (uint32 vertexIndex = 0; vertexIndex < numVertices; vertexIndex += 3) {
+			// Create a single "slice" of the ellipse (like a pizza)
+			float32 currAngle = (vertexIndex / 3.f) * angleIncrements;
+			float32 nextAngle = (vertexIndex / 3.f + 1.f) * angleIncrements;
+
+			vertices[vertexIndex].position = Vector2 { 0.f, 0.f };
+			vertices[vertexIndex].color = color;
+
+			vertices[vertexIndex + 1].position = Vector2 { a * cosf(currAngle), b * sinf(currAngle) };
+			vertices[vertexIndex + 1].color = color;
+
+			vertices[vertexIndex + 2].position = Vector2 { a * cosf(nextAngle), b * sinf(nextAngle) };
+			vertices[vertexIndex + 2].color = color;
+		}
+
+		shape.load(vertices, numVertices, renderer);
+	}
+
+	void unload() {
+		shape.unload();
+	}
+
+	float32 getArea() {
+		return 0.f;
+	}
+};
 
 EM_BOOL onPlayClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData);
 EM_BOOL onStopClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData);
 EM_BOOL update(float time, void* userData);
 
+// Global Variables
 WebglContext context;
 OrthographicRenderer renderer;
-TriangleShape shape;
+Pill pill;
 MainLoop mainLoop;
 
 int main() {
@@ -26,14 +80,23 @@ int main() {
 	return 0;
 }
 
+EM_BOOL update(float deltaTimeSeconds, void* userData) {
+	renderer.render();
+	pill.shape.render(&renderer);
+	return true;
+}
+
+//
+// Interactions with DOM handled below
+//
 EM_BOOL onPlayClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData) {
 	printf("Play clicked\n");
 	
-	renderer.load();
-	shape.vertices[0] = { Vector2 { -1, -1 }, Vector4 { 1, 0, 0, 1 } };
-	shape.vertices[1] = { Vector2 { 0, 1 }, Vector4{ 0, 1, 0, 1 } };
-	shape.vertices[2] = { Vector2 { 1, -1 }, Vector4 { 0, 0, 1, 1 } };
-	shape.load(&renderer);
+	renderer.load(&context);
+	pill.width = 100.f;
+	pill.height = 50.f;
+	pill.shape.model = pill.shape.model.translateByVec2(Vector2 { context.width / 2.f, context.height / 2.f });
+	pill.load(&renderer, 64);
 	mainLoop.run(update);
 	return true;
 }
@@ -41,13 +104,7 @@ EM_BOOL onPlayClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, voi
 EM_BOOL onStopClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData) {
 	printf("Stop clicked\n");
 	mainLoop.stop();
-	shape.unload();
+	pill.unload();
 	renderer.unload();
 	return true;
-}
-
-EM_BOOL update(float deltaTimeSeconds, void* userData) {
-	renderer.render();
-	shape.render(&renderer);
-	return true;
 }
\ No newline at end of file
-- 
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