Drawing an ellipse

7 files changed, 153 insertions, 58 deletions

diff --git a/frontend/2d/_collisions/pill_line/dist/output.wasm b/frontend/2d/_collisions/pill_line/dist/output.wasm
index be1afc5..92ee1f2 100755
--- a/frontend/2d/_collisions/pill_line/dist/output.wasm
+++ b/frontend/2d/_collisions/pill_line/dist/output.wasm
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
diff --git a/frontend/shared_cpp/OrthographicRenderer.cpp b/frontend/shared_cpp/OrthographicRenderer.cpp
index b6bd5b6..1d62c04 100644
--- a/frontend/shared_cpp/OrthographicRenderer.cpp
+++ b/frontend/shared_cpp/OrthographicRenderer.cpp
@@ -1,4 +1,6 @@
 #include "OrthographicRenderer.h"
+#include "WebglContext.h"
+#include "mathlib.h"
 
 const char* orthographicVertex = 
 "attribute vec2 position; \n"
@@ -18,7 +20,7 @@ const char* orthographicFragment =
 "    gl_FragColor = VertexColor; \n"
 "}";
 
-void OrthographicRenderer::load() {
+void OrthographicRenderer::load(WebglContext* context) {
 	printf("Compiling orthographic shader...\n");
 	shader = loadShader(orthographicVertex, orthographicFragment);
 
@@ -27,6 +29,7 @@ void OrthographicRenderer::load() {
 	attributes.color = getShaderAttribute(shader, "color");
 	uniforms.projection = getShaderUniform(shader, "projection");
 	uniforms.model = getShaderUniform(shader, "model");
+	projection = Mat4x4().getOrthographicMatrix(0, context->width, 0, context->height);
 
 	printf("Orthographic shader compiled.\n");
 }
@@ -47,3 +50,45 @@ void OrthographicRenderer::unload() {
     glClear(GL_COLOR_BUFFER_BIT);
 	glDeleteProgram(shader);
 }
+
+
+void OrthographicShape::load(OrthographicVertex* inVertices, uint32 inNumVertices, OrthographicRenderer* renderer) {
+	vertices = inVertices;
+	numVertices = inNumVertices;
+	useShader(renderer->shader);
+
+	glGenVertexArrays(1, &vao);
+	glBindVertexArray(vao);
+
+	glGenBuffers(1, &vbo);
+	glBindBuffer(GL_ARRAY_BUFFER, vbo);
+	glBufferData(GL_ARRAY_BUFFER, inNumVertices * sizeof(OrthographicVertex), &vertices[0], GL_STATIC_DRAW);
+
+	glEnableVertexAttribArray(renderer->attributes.position);
+	glVertexAttribPointer(renderer->attributes.position, 2, GL_FLOAT, GL_FALSE, sizeof(OrthographicVertex), (GLvoid *)0);
+
+	glEnableVertexAttribArray(renderer->attributes.color);
+	glVertexAttribPointer(renderer->attributes.color, 4, GL_FLOAT, GL_FALSE, sizeof(OrthographicVertex), (GLvoid *)offsetof(OrthographicVertex, color));
+
+	glBindBuffer(GL_ARRAY_BUFFER, 0);
+	glBindVertexArray(0);
+}
+
+void OrthographicShape::render(OrthographicRenderer* renderer) {
+	setShaderMat4(renderer->uniforms.model, model);
+
+	glBindVertexArray(vao);
+	glDrawArrays(GL_TRIANGLES, 0, numVertices);
+	glBindVertexArray(0);
+}
+
+void OrthographicShape::unload() {
+	glDeleteVertexArrays(1, &vao);
+	glDeleteBuffers(1, &vbo);
+
+	if (vertices != NULL) {
+		delete vertices;
+	}
+
+	vertices = NULL;
+}
\ No newline at end of file
diff --git a/frontend/shared_cpp/OrthographicRenderer.h b/frontend/shared_cpp/OrthographicRenderer.h
index c72639e..0cdfc78 100644
--- a/frontend/shared_cpp/OrthographicRenderer.h
+++ b/frontend/shared_cpp/OrthographicRenderer.h
@@ -1,9 +1,12 @@
 #pragma once
 
+#include "WebglContext.h"
 #include "types.h"
 #include "Shader.h"
 #include "mathlib.h"
 
+struct WebglContext;
+
 struct OrthographicRenderer {
 	Mat4x4 projection;
 	uint32 shader;
@@ -18,7 +21,7 @@ struct OrthographicRenderer {
 		int32 model;
 	} uniforms;
 
-	void load();
+	void load(WebglContext* context);
 	void render();
 	void unload();
 };
@@ -28,50 +31,14 @@ struct OrthographicVertex {
 	Vector4 color;
 };
 
-template <uint32 N>
 struct OrthographicShape {
 	uint32 vao;
 	uint32 vbo;
-	OrthographicVertex vertices[N];
+	uint32 numVertices = 0;
+	OrthographicVertex* vertices = NULL;
 	Mat4x4 model;
 
-	void load(OrthographicRenderer* renderer);
+	void load(OrthographicVertex* vertices, uint32 numVertices, OrthographicRenderer* renderer);
 	void render(OrthographicRenderer* renderer);
 	void unload();
-};
-
-template <uint32 N>
-void OrthographicShape<N>::load(OrthographicRenderer* renderer) {
-	useShader(renderer->shader);
-
-	glGenVertexArrays(1, &vao);
-	glBindVertexArray(vao);
-
-	glGenBuffers(1, &vbo);
-	glBindBuffer(GL_ARRAY_BUFFER, vbo);
-	glBufferData(GL_ARRAY_BUFFER, N * sizeof(OrthographicVertex), &vertices[0], GL_STATIC_DRAW);
-
-	glEnableVertexAttribArray(renderer->attributes.position);
-	glVertexAttribPointer(renderer->attributes.position, 2, GL_FLOAT, GL_FALSE, sizeof(OrthographicVertex), (GLvoid *)0);
-
-	glEnableVertexAttribArray(renderer->attributes.color);
-	glVertexAttribPointer(renderer->attributes.color, 4, GL_FLOAT, GL_FALSE, sizeof(OrthographicVertex), (GLvoid *)offsetof(OrthographicVertex, color));
-
-	glBindBuffer(GL_ARRAY_BUFFER, 0);
-	glBindVertexArray(0);
-}
-
-template <uint32 N>
-void OrthographicShape<N>::render(OrthographicRenderer* renderer) {
-	setShaderMat4(renderer->uniforms.model, model);
-
-	glBindVertexArray(vao);
-	glDrawArrays(GL_TRIANGLES, 0, 3);
-	glBindVertexArray(0);
-}
-
-template <uint32 N>
-void OrthographicShape<N>::unload() {
-	glDeleteVertexArrays(1, &vao);
-	glDeleteBuffers(1, &vbo);
-}
\ No newline at end of file
+};
\ No newline at end of file
diff --git a/frontend/shared_cpp/WebglContext.h b/frontend/shared_cpp/WebglContext.h
index 1ea1c91..017498f 100644
--- a/frontend/shared_cpp/WebglContext.h
+++ b/frontend/shared_cpp/WebglContext.h
@@ -7,8 +7,12 @@
 
 struct WebglContext {
 	EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context;
+	int width = 640;
+	int height = 480;
 
-	void init(const char* query, int width = 640, int height = 480) {
+	void init(const char* query, int inWidth = 640, int inHeight = 480) {
+		width = inWidth;
+		height = inHeight;
 		emscripten_set_canvas_element_size( query, width, height);
 		
 		EmscriptenWebGLContextAttributes attrs;
diff --git a/frontend/shared_cpp/mathlib.h b/frontend/shared_cpp/mathlib.h
index 93ddbbd..7595045 100644
--- a/frontend/shared_cpp/mathlib.h
+++ b/frontend/shared_cpp/mathlib.h
@@ -41,6 +41,10 @@ struct Vector2 {
     Vector2 getPerp() {
         return { -y, x };
     }
+
+    void printDebug(const char* name) {
+        printf("%s=Vector2(%f, %f)\n", name, x, y);
+    }
 };
 
 struct Vector3 {
@@ -54,6 +58,22 @@ struct Vector4 {
     float y = 0.f;
     float z = 0.f;
     float w = 0.f;
+
+    float length() {
+        return sqrtf(x * x + y * y + z * z + w * w);
+    }
+
+    Vector4 normalize() {
+        float len = length();
+        float inverseLength = len == 0 ? 1.0 : 1.0 / len;
+
+        return { x * inverseLength, y * inverseLength, z * inverseLength, w * inverseLength };
+    }
+
+    Vector4 fromColor(float r, float g, float b, float a) {
+        float scale = 1.f / 255.f;
+        return { r * scale, g * scale, b * scale, a * scale };
+    }
 };
 
 struct Mat4x4 {
@@ -123,7 +143,7 @@ struct Mat4x4 {
 	void print() {
 		printf("[ ");
 		for (int idx = 0; idx < 16; idx++) {
-			printf("%d, ", idx);
+			printf("%f, ", m[idx]);
 		}
 		printf(" ]\n");
 	}
diff --git a/frontend/shared_cpp/types.h b/frontend/shared_cpp/types.h
index 7bac7f3..3739699 100644
--- a/frontend/shared_cpp/types.h
+++ b/frontend/shared_cpp/types.h
@@ -14,3 +14,5 @@ typedef unsigned long uint64;
 
 typedef float float32;
 typedef double float64;
+
+#define PI 3.14159265358979323846
\ No newline at end of file