diff --git a/main.c b/main.c
index f26a460..5de8a9c 100644
--- a/main.c
+++ b/main.c
@@ -45,6 +45,59 @@ typedef struct {
 static const char *layers[] = { "VK_LAYER_KHRONOS_validation" };
 static const char *swapchain_ext_name = VK_KHR_SWAPCHAIN_EXTENSION_NAME;
 
+// Initial parameters
+static params_t params = {
+#ifdef JULIA
+	.julia = {
+#ifdef JULIA_C_RE
+		.re = JULIA_C_RE,
+#endif
+#ifdef JULIA_C_IM
+		.im = JULIA_C_IM,
+#endif
+	},
+#endif
+#if defined(CENTRE_RE) || defined(CENTRE_IM)
+	.centre = {
+#ifdef CENTRE_RE
+		.re = CENTRE_RE,
+#endif
+#ifdef CENTRE_IM
+		.im = CENTRE_IM,
+#endif
+	},
+#endif
+	.scale = 1.0,
+#ifdef POWRATE
+	.zpow = 2.0,
+#endif
+};
+
+static void
+mouse_button_callback(GLFWwindow *window, int button, int action, int mods)
+{
+	(void)window;
+	(void)button;
+	(void)mods;
+
+	if (action == GLFW_RELEASE)
+		return;
+
+	double x, y;
+	glfwGetCursorPos(window, &x, &y);
+
+	double zx = 4.0 * (x / params.width - 0.5);
+	double zy = 4.0 * (y / params.height - 0.5);
+	zx *= params.width / params.height;
+	
+	zx = params.scale * zx + params.centre.re;
+	zy = params.scale * zy + params.centre.im;
+
+	printf("CLICKED: %.8f + %.8fi\n", zx, zy);
+	params.centre.re = zx;
+	params.centre.im = zy;
+}
+
 static VkShaderModule load_shader_module(VkDevice dev, const char *path)
 {
 	static char buf[MAX_SHADER_SIZE]
@@ -69,7 +122,7 @@ static VkShaderModule load_shader_module(VkDevice dev, const char *path)
 
 int main(void)
 {
-	// Set up window and surface
+	// Set up window
 	glfwInit();
 	glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
 	glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
@@ -77,10 +130,11 @@ int main(void)
 	const GLFWvidmode *mode = glfwGetVideoMode(monitor);
 	GLFWwindow *window = glfwCreateWindow(
 	    mode->width, mode->height, "GPU Fractal", monitor, NULL);
-	/* GLFWwindow *window */
-	/*     = glfwCreateWindow(900, 900, "GPU Fractal", NULL, NULL); */
 	assert(window);
 
+	// Register mouse click callback
+	glfwSetMouseButtonCallback(window, mouse_button_callback);
+
 	// Initialise Vulkan instance.
 	const VkApplicationInfo app_info = {
 		.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO,
@@ -476,36 +530,9 @@ int main(void)
 	result = vkCreateFence(dev, &fence_config, NULL, &in_flight);
 	assert(result == VK_SUCCESS);
 
-	// Prepare parameters
-	params_t params = {
-		.width = (float)swapchain_extent.width,
-		.height = (float)swapchain_extent.height,
-#ifdef JULIA
-		.julia = {
-#ifdef JULIA_C_RE
-			.re = JULIA_C_RE,
-#endif
-#ifdef JULIA_C_IM
-			.im = JULIA_C_IM,
-#endif
-		},
-#endif
-#if defined(CENTRE_RE) || defined(CENTRE_IM)
-		.centre = {
-#ifdef CENTRE_RE
-			.re = CENTRE_RE,
-#endif
-#ifdef CENTRE_IM
-			.im = CENTRE_IM,
-#endif
-		},
-#endif
-		.scale = 1.0,
-#ifdef POWRATE
-		.zpow = 2.0,
-#endif
-	};
-
+	// Initialise shader parameters
+	params.width = (float)swapchain_extent.width;
+	params.height = (float)swapchain_extent.height;
 #ifdef JULIA_DTHETA
 	const double dtheta = JULIA_DTHETA;
 	const double complex rotz = cexp(I * dtheta);