diff --git a/README b/README
index 4d39492..d0a27e9 100644
--- a/README
+++ b/README
@@ -13,7 +13,7 @@ TODO:
 	add input abstraction for SDL
 	store meshes separately from entities for reuse
 	add a function to update camera transforms only once per frame, per shader
-	fix example Makefile dependenies
+	update camera to use quaternions for rotation
 
 Dependencies:
 	assimp >= 5.0.0
diff --git a/examples/Makefile b/examples/Makefile
index 28764a4..065f0ff 100644
--- a/examples/Makefile
+++ b/examples/Makefile
@@ -19,14 +19,31 @@ EXAMPLE_SOURCES = \
 	simple_mesh/main.cpp \
 EXAMPLE_OBJECTS = $(patsubst %/, $(OBJDIR)/%.o, $(dir $(EXAMPLE_SOURCES)))
 
-all: mkdirs $(EXAMPLE_OBJECTS)
+EXAMPLES = hello_world simple_mesh assimp_loading
+BINARIES = $(patsubst %, $(BINDIR)/%, $(EXAMPLES))
 
--include $(OBJDIR)/*.d
+all: mkdirs $(BINARIES)
+.PHONY: all
+
+$(OBJDIR)/hello_world.o:
+	$(CXX) $(CXXFLAGS) -c -MMD hello_world/main.cpp -o $@
+
+$(BINDIR)/hello_world: $(OBJDIR)/hello_world.o
+	$(CXX) -o $@ $(LDFLAGS) $^ $(LIB) $(ASSIMP_LIB)
+
+$(OBJDIR)/simple_mesh.o:
+	$(CXX) $(CXXFLAGS) -c -MMD simple_mesh/main.cpp -o $@
+
+$(BINDIR)/simple_mesh: $(OBJDIR)/simple_mesh.o
+	$(CXX) -o $@ $(LDFLAGS) $^ $(LIB) $(ASSIMP_LIB)
 
-$(EXAMPLE_OBJECTS):
-	$(CXX) $(CXXFLAGS) -c -MMD $(basename $(notdir $@))/main.cpp -o $@
-	$(CXX) -o $(BINDIR)/$(notdir $(basename $@)) $(LDFLAGS) $@ $(LIB) \
-		$(ASSIMP_LIB)
+$(OBJDIR)/assimp_loading.o:
+	$(CXX) $(CXXFLAGS) -c -MMD assimp_loading/main.cpp -o $@
+
+$(BINDIR)/assimp_loading: $(OBJDIR)/assimp_loading.o
+	$(CXX) -o $@ $(LDFLAGS) $^ $(LIB) $(ASSIMP_LIB)
+
+-include $(OBJDIR)/*.d
 
 mkdirs:
 	@mkdir -p $(BINDIR) $(OBJDIR)
@@ -35,3 +52,4 @@ mkdirs:
 clean:
 	rm -rf $(OBJDIR)/* bin/*
 .PHONY: clean
+
diff --git a/include/camera.h b/include/camera.h
index b545645..8346416 100644
--- a/include/camera.h
+++ b/include/camera.h
@@ -30,16 +30,37 @@ enum projection_type
 };
 
 
-v2f cameraUnproject(camera& cam, int x, int y, int vp_width, int vp_height);
+v2f
+cameraUnproject(camera& cam, int x, int y, int vp_width, int vp_height);
 
-v3f cameraCreateRay(camera& cam, v2i vp_coords, v2i vp_dims);
+v3f
+cameraCreateRay(camera& cam, v2i vp_coords, v2i vp_dims);
 
-bool cameraIntersectPlane(camera& cam, v3f ray, v3f plane_origin, v3f plane_normal, v3f& intersection);
+bool
+cameraIntersectPlane(camera& cam,
+	v3f ray,
+	v3f plane_origin,
+	v3f plane_normal,
+	v3f& intersection);
 
-void cameraInitPerspective(camera& cam, glm::vec3 position, glm::vec3 target, glm::vec3 world_up);
+void
+cameraInitPerspective(camera& cam,
+	glm::vec3 position,
+	glm::vec3 target,
+	glm::vec3 world_up,
+	float aspect_ratio = 16.f / 9.f);
 
-void cameraMove(camera& cam, bool up, bool left, bool down, bool right, bool forward, bool backward);
+void
+cameraMove(camera& cam,
+	bool up,
+	bool left,
+	bool down,
+	bool right,
+	bool forward,
+	bool backward);
 
-void cameraRotate(camera& cam, int32	xrel, int32 yrel);
+void
+cameraRotate(camera& cam, int32	xrel, int32 yrel);
 
-void cameraRoll(camera& cam, bool CW, bool CCW);
+void
+cameraRoll(camera& cam, bool CW, bool CCW);
diff --git a/include/entity.h b/include/entity.h
index ba65c3a..fc16687 100644
--- a/include/entity.h
+++ b/include/entity.h
@@ -28,6 +28,8 @@ bool entInitModel(entity& e, const char* model_path);
 
 bool entInitMesh(entity& e, simple_mesh* mesh, GLenum draw_mode);
 
+void entUpdateSimpleMesh(entity& e, simple_mesh* mesh, GLenum draw_mode);
+
 void entFree(entity& e);
 
 void entSetWorldPosition(entity& e, glm::vec3 v);
diff --git a/include/input.h b/include/input.h
index 1be9403..806a716 100644
--- a/include/input.h
+++ b/include/input.h
@@ -1,6 +1,9 @@
 
 #pragma once
 
+#include <SDL2/SDL.h>
+
+
 struct input_state
 {
 	bool window_closed;
@@ -11,6 +14,10 @@ struct input_state
 	bool down;
 };
 
+void
+inputProcessEvent(input_state* is, SDL_Event& e);
+
+// NOTE: convenience function that provides a while(SDL_PollEvents()) loop
 void
 inputProcessEvents(input_state* is);
 
diff --git a/include/render_object.h b/include/render_object.h
index eeae99e..5196e47 100644
--- a/include/render_object.h
+++ b/include/render_object.h
@@ -28,3 +28,5 @@ roDraw(render_objects* r_ojbs,
 	shader_wrapper sw,
 	light_group* lights);
 
+void
+roUpdateSimpleMesh(render_objects* r_objs, simple_mesh* mesh, GLenum draw_mode);
diff --git a/include/renderer.h b/include/renderer.h
index cf7916c..52b3388 100644
--- a/include/renderer.h
+++ b/include/renderer.h
@@ -92,3 +92,6 @@ renAddLight(render_state* rs,
 	glm::vec3 color = glm::vec3(1, 1, 1),
 	float intensity = 1.0);
 
+glm::vec2
+renGetWindowDims(render_state* rs);
+
diff --git a/src/camera.cpp b/src/camera.cpp
index 0fa34f0..e89b563 100644
--- a/src/camera.cpp
+++ b/src/camera.cpp
@@ -1,4 +1,6 @@
 
+#include <cassert>
+
 #include <GL/glew.h>
 
 #include "camera.h"
@@ -8,7 +10,6 @@
 #define ROTATE_SPEED 0.005f
 #define CAMERA_Z_CLAMP_ANGLE 85.f
 #define FOV 60.f
-#define ASPECT_RATIO 16.f/9.f
 #define NEAR_CLIP_PLANE 20.f
 
 
@@ -19,20 +20,29 @@ inline glm::vec3 convertv3f(v3f v);
 // interface
 
 void
-cameraInitPerspective(camera& cam, glm::vec3 position, glm::vec3 target, glm::vec3 world_up)
+cameraInitPerspective(camera& cam,
+	glm::vec3 position,
+	glm::vec3 target,
+	glm::vec3 world_up,
+	float aspect_ratio)
 {
+	assert(aspect_ratio > 0);
+
 	cam.position = position;
 	cam.target = target;
 	cam.world_up = world_up;
-	cam.projection = glm::infinitePerspective(glm::radians(FOV), ASPECT_RATIO, NEAR_CLIP_PLANE);
+	cam.projection = glm::infinitePerspective(glm::radians(FOV),
+		aspect_ratio,
+		NEAR_CLIP_PLANE);
 
 	cam.forward = glm::normalize(target - position);
 	cam.left = glm::normalize(glm::cross(cam.world_up, cam.forward));
 	cam.up = glm::normalize(glm::cross(cam.forward, cam.left));
 
 	cam.hAngle = glm::atan(cam.forward.x, cam.forward.y);
-	// NOTE: using pythagoras' to get absolute value of relative axis for vAngle component
-	real32 len = glm::sqrt(glm::pow(cam.forward.y, 2) + glm::pow(cam.forward.x, 2));
+	// NOTE: get absolute value of relative axis for vAngle component
+	real32 len = glm::sqrt(glm::pow(cam.forward.y, 2) +
+		glm::pow(cam.forward.x, 2));
 	cam.vAngle = glm::atan(cam.forward.z, len);
 
 	cam.view = glm::lookAt(cam.position, cam.position + cam.forward, cam.up);
diff --git a/src/entity.cpp b/src/entity.cpp
index 76226ac..5253599 100644
--- a/src/entity.cpp
+++ b/src/entity.cpp
@@ -45,6 +45,12 @@ entInitMesh(entity& e, simple_mesh* mesh, GLenum draw_mode)
 	return true;
 }
 
+void
+entUpdateSimpleMesh(entity& e, simple_mesh* mesh, GLenum draw_mode)
+{
+	roUpdateSimpleMesh(e.render_objs, mesh, draw_mode);
+}
+
 void
 entFree(entity& e)
 {
diff --git a/src/input.cpp b/src/input.cpp
index 4ff1248..1f2ded3 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -1,39 +1,46 @@
 
-#include <SDL2/SDL.h>
+#include <cassert>
 
 #include "input.h"
 
 
+void
+inputProcessEvent(input_state* is, SDL_Event& e)
+{
+	assert(is != nullptr);
+
+	switch (e.type) {
+		case SDL_QUIT:
+			is->window_closed = true;
+			break;
+		case SDL_KEYDOWN:
+			switch (e.key.keysym.sym) {
+				case SDLK_ESCAPE: is->escape = true; break;
+				case SDLK_LEFT: is->left = true; break;
+				case SDLK_RIGHT: is->right = true; break;
+				case SDLK_UP: is->up = true; break;
+				case SDLK_DOWN: is->down = true; break;
+			}
+			break;
+		case SDL_KEYUP:
+			switch (e.key.keysym.sym) {
+				case SDLK_ESCAPE: is->escape = false; break;
+				case SDLK_LEFT: is->left = false; break;
+				case SDLK_RIGHT: is->right = false; break;
+				case SDLK_UP: is->up = false; break;
+				case SDLK_DOWN: is->down = false; break;
+			}
+			break;
+		default: break;
+	}
+}
+
 void
 inputProcessEvents(input_state* is)
 {
 	SDL_Event e;
 
-	while (SDL_PollEvent(&e)) {
-		switch (e.type) {
-			case SDL_QUIT:
-				is->window_closed = true;
-				break;
-			case SDL_KEYDOWN:
-				switch (e.key.keysym.sym) {
-					case SDLK_ESCAPE: is->escape = true; break;
-					case SDLK_LEFT: is->left = true; break;
-					case SDLK_RIGHT: is->right = true; break;
-					case SDLK_UP: is->up = true; break;
-					case SDLK_DOWN: is->down = true; break;
-				}
-				break;
-			case SDL_KEYUP:
-				switch (e.key.keysym.sym) {
-					case SDLK_ESCAPE: is->escape = false; break;
-					case SDLK_LEFT: is->left = false; break;
-					case SDLK_RIGHT: is->right = false; break;
-					case SDLK_UP: is->up = false; break;
-					case SDLK_DOWN: is->down = false; break;
-				}
-				break;
-			default: break;
-		}
-	}
+	while (SDL_PollEvent(&e))
+		inputProcessEvent(is, e);
 }
 
diff --git a/src/render_object.cpp b/src/render_object.cpp
index 48a00e1..7a216dc 100644
--- a/src/render_object.cpp
+++ b/src/render_object.cpp
@@ -46,7 +46,10 @@ void drawSimple(render_objects* r_objs,
 	shader_wrapper sw,
 	light_group* lights);
 inline void enableGLFloatBuffer(uint buffer_id, uint location);
-bool initGLFloatBuffer(glm::vec3* buffer, uint count, GLuint& buffer_id);
+bool initGLFloatBuffer(glm::vec3* buffer,
+		uint count,
+		GLuint& buffer_id,
+		GLenum usage = GL_STATIC_DRAW);
 bool initGLIndexBuffer(uint* buffer, uint num_indices, GLuint& buffer_id);
 bool initGLTexture(const util_image image, GLuint& tex_id);
 bool loadMeshIntoGL(default_render_object* ro_out, mesh_info* mi_in);
@@ -93,10 +96,12 @@ roInitSimpleMesh(simple_mesh& mesh_in, GLenum draw_mode)
 
 	if (initGLFloatBuffer(mesh_in.vertices,
 			mesh_in.num_vertices,
-			objects->vertex_buffer_id) &&
+			objects->vertex_buffer_id,
+			GL_DYNAMIC_DRAW) &&
 		initGLFloatBuffer(mesh_in.vert_colors,
 			mesh_in.num_vertices,
-			objects->vertex_color_buffer_id))
+			objects->vertex_color_buffer_id,
+			GL_DYNAMIC_DRAW))
 	{
 		objects->model_transform = mesh_in.model_transform;
 		objects->vertex_count = mesh_in.num_vertices;
@@ -145,6 +150,28 @@ roDraw(render_objects* r_objs,
 		drawDefault(r_objs, world_transform, cam, sw, lights);
 }
 
+void
+roUpdateSimpleMesh(render_objects* r_objs, simple_mesh* mesh, GLenum draw_mode)
+{
+	assert(r_objs != nullptr && r_objs->objects != nullptr);
+	assert(mesh != nullptr && mesh->vertices != nullptr);
+	simple_render_object* sro = (simple_render_object*) r_objs->objects;
+	assert(sro->vertex_count == mesh->num_vertices);
+
+	sro->draw_mode = draw_mode;
+	glBindBuffer(GL_ARRAY_BUFFER, sro->vertex_buffer_id);
+	glBufferSubData(
+		GL_ARRAY_BUFFER,
+		0,
+		3 * sro->vertex_count * sizeof(GLfloat),
+		mesh->vertices);
+	glBindBuffer(GL_ARRAY_BUFFER, sro->vertex_color_buffer_id);
+	glBufferSubData(
+		GL_ARRAY_BUFFER,
+		0,
+		3 * sro->vertex_count * sizeof(GLfloat),
+		mesh->vert_colors);
+}
 
 // internal
 
@@ -216,14 +243,17 @@ enableGLFloatBuffer(uint buffer_id, uint location)
 }
 
 bool
-initGLFloatBuffer(glm::vec3* buffer, uint count, GLuint& buffer_id)
+initGLFloatBuffer(glm::vec3* buffer,
+	uint count,
+	GLuint& buffer_id,
+	GLenum usage)
 {
 	glGenBuffers(1, &buffer_id);
 	glBindBuffer(GL_ARRAY_BUFFER, buffer_id);
 	glBufferData(GL_ARRAY_BUFFER,
 		count * 3 * sizeof(GLfloat), // NOTE: 3 floats per vertex prop
 		buffer,
-		GL_STATIC_DRAW);
+		usage);
 
 	return (glGetError() == GL_NO_ERROR);
 }
diff --git a/src/renderer.cpp b/src/renderer.cpp
index d287e47..064f243 100644
--- a/src/renderer.cpp
+++ b/src/renderer.cpp
@@ -164,6 +164,15 @@ renAddLight(render_state* rs, glm::vec3 pos, glm::vec3 color, float intensity)
 	return true;
 }
 
+glm::vec2
+renGetWindowDims(render_state* rs)
+{
+	int x = 0, y = 0;
+	SDL_GetWindowSize(rs->handles->window, &x, &y);
+	glm::vec2 dims(x, y);
+	return dims;
+}
+
 
 // internal