*
* TODO:
*
- * - Add code to add boxes
- * - Add circle object
+ * - Add code to add boxes
+ * - Add circle object
+ * - Try out this idea: make constraint solver take mean of all
+ * corrections at the end instead of meaning as it goes.
*/
#include <gtk/gtk.h>
#include <cairo-xlib.h>
#include <gdk/gdkx.h>
#include <stdlib.h>
+#include <string.h>
#include <sys/time.h>
#include <math.h>
typedef struct _Object Object;
typedef struct _Stick Stick;
typedef struct _String String;
+typedef struct _Polygon Polygon;
typedef struct _Offset Offset;
typedef struct _Model Model;
int dx, dy;
};
+struct _Polygon {
+ int num_points;
+ Point *points;
+ Vector *normals;
+ int edge;
+};
+
struct _Model {
int num_objects;
Object *objects;
String *strings;
int num_offsets;
Offset *offsets;
+ int num_polygons;
+ Polygon *polygons;
double k;
double friction;
double theta;
};
+static void
+polygon_init (Polygon *p, int num_points, ...)
+{
+ double dx, dy, length;
+ int i, j;
+ va_list ap;
+
+ /* Polygons are defined counter-clock-wise in a coordinate system
+ * with the y-axis pointing down. */
+
+ va_start (ap, num_points);
+ p->num_points = num_points;
+ p->points = g_new (Point, num_points);
+
+ for (i = 0; i < num_points; i++) {
+ p->points[i].x = va_arg (ap, double);
+ p->points[i].y = va_arg (ap, double);
+ }
+ va_end (ap);
+
+ p->normals = g_new (Vector, p->num_points);
+ /* Compute outward pointing normals. p->normals[i] is the normal
+ * for the edged between p->points[i] and p->points[i + 1]. */
+ for (i = 0; i < p->num_points; i++) {
+ j = (i + 1) % p->num_points;
+ dx = p->points[j].x - p->points[i].x;
+ dy = p->points[j].y - p->points[i].y;
+ length = sqrt (dx * dx + dy * dy);
+ p->normals[i].x = -dy / length;
+ p->normals[i].y = dx / length;
+ }
+}
+
+static void
+polygon_init_diamond (Polygon *polygon, double x, double y)
+{
+ return polygon_init (polygon, 5,
+ x, y,
+ x + 10, y + 40,
+ x + 90, y + 40,
+ x + 100, y,
+ x + 50, y - 20);
+}
+
+static void
+polygon_init_rectangle (Polygon *polygon, double x0, double y0,
+ double x1, double y1)
+{
+ return polygon_init (polygon, 4, x0, y0, x0, y1, x1, y1, x1, y0);
+}
+
+static void
+model_init_polygons (Model *model)
+{
+ const int num_polygons = 5;
+
+ model->polygons = g_new (Polygon, num_polygons);
+ polygon_init_diamond (&model->polygons[0], 250, 300);
+ polygon_init_diamond (&model->polygons[1], 400, 150);
+ polygon_init_rectangle (&model->polygons[2], -100, 200, 200, 250);
+ polygon_init_rectangle (&model->polygons[3], -200, ground_level,
+ 1200, ground_level + 400);
+
+ polygon_init_rectangle (&model->polygons[4], 300, 320, 400, 350);
+
+
+ model->num_polygons = num_polygons;
+}
+
static void
model_init_snake (Model *model)
{
const int num_sticks = num_objects * 2 - 3;
int i;
+ memset (model, 0, sizeof *model);
model->objects = g_new (Object, num_objects);
model->num_objects = num_objects;
model->sticks = g_new (Stick, num_sticks);
model->num_sticks = num_sticks;
- model->strings = NULL;
- model->num_strings = 0;
- model->offsets = NULL;
- model->num_offsets = 0;
+ model_init_polygons (model);
for (i = 0; i < num_objects; i++) {
model->objects[i].position.x = random() % 200 + 20;
{
const int num_objects = 20;
const int num_sticks = num_objects - 1;
- const int stick_length = 5;
+ const int stick_length = 10;
int i;
+ memset (model, 0, sizeof *model);
model->objects = g_new (Object, num_objects);
model->num_objects = num_objects;
model->sticks = g_new (Stick, num_sticks);
model->num_sticks = num_sticks;
- model->strings = NULL;
- model->num_strings = 0;
- model->offsets = NULL;
- model->num_offsets = 0;
+ model_init_polygons (model);
for (i = 0; i < num_objects; i++) {
model->objects[i].position.x = 200;
double x, y;
int i, j, index, stick_index;
+ memset (model, 0, sizeof *model);
model->objects = g_new (Object, num_objects);
model->num_objects = num_objects;
model->sticks = g_new (Stick, num_sticks);
model->num_sticks = num_sticks;
- model->strings = NULL;
- model->num_strings = 0;
model->offsets = g_new (Offset, num_ropes - 1);
model->num_offsets = num_ropes - 1;
+ model_init_polygons (model);
for (i = 0; i < num_ropes; i++) {
for (j = 0; j < num_rope_objects; j++) {
double x, y;
int i, j, index, string_index;
+ memset (model, 0, sizeof *model);
model->objects = g_new (Object, num_objects);
model->num_objects = num_objects;
- model->sticks = NULL;
- model->num_sticks = 0;
model->strings = g_new (String, num_strings);
model->num_strings = num_strings;
model->offsets = g_new (Offset, num_ropes - 1);
model->num_offsets = num_ropes - 1;
+ model_init_polygons (model);
for (i = 0; i < num_ropes; i++) {
for (j = 0; j < num_rope_objects; j++) {
model_fini (Model *model)
{
g_free (model->objects);
- model->objects = NULL;
- model->num_objects = 0;
g_free (model->sticks);
- model->sticks = NULL;
- model->sticks = 0;
g_free (model->strings);
- model->strings = NULL;
- model->strings = 0;
g_free (model->offsets);
- model->offsets = NULL;
- model->num_offsets = 0;
+ memset (model, 0, sizeof *model);
}
static void
y = o->position.y;
o->position.x =
- x + (x - o->previous_position.x) + o->force.x * step * step;
+ x + 0.9 * (x - o->previous_position.x) + o->force.x * step * step;
o->position.y =
- y + (y - o->previous_position.y) + o->force.y * step * step;
+ y + 0.9 * (y - o->previous_position.y) + o->force.y * step * step;
o->previous_position.x = x;
o->previous_position.y = y;
#endif
}
+static int
+polygon_contains_point (Polygon *polygon, Point *point)
+{
+ int i;
+ double dx, dy;
+
+ for (i = 0; i < polygon->num_points; i++) {
+ dx = point->x - polygon->points[i].x;
+ dy = point->y - polygon->points[i].y;
+
+ if (polygon->normals[i].x * dx + polygon->normals[i].y * dy >= 0)
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+static void
+polygon_reflect_object (Polygon *polygon, Object *object)
+{
+ int i, edge;
+ double d, distance;
+ Vector *n;
+
+ distance = -1000;
+ for (i = 0; i < polygon->num_points; i++) {
+ d = polygon->normals[i].x * (object->position.x - polygon->points[i].x) +
+ polygon->normals[i].y * (object->position.y - polygon->points[i].y);
+
+ if (d > distance) {
+ distance = d;
+ edge = i;
+ polygon->edge = i;
+ n = &polygon->normals[i];
+ }
+ }
+
+ object->position.x -= (1 + elasticity) * distance * n->x;
+ object->position.y -= (1 + elasticity) * distance * n->y;
+
+ distance =
+ n->x * (object->previous_position.x - polygon->points[edge].x) +
+ n->y * (object->previous_position.y - polygon->points[edge].y);
+
+ object->previous_position.x -= (1 + elasticity) * distance * n->x;
+ object->previous_position.y -= (1 + elasticity) * distance * n->y;
+}
+
static void
-model_constrain (Model *model, double step)
+model_constrain_polygon (Model *model, Polygon *polygon)
+{
+ int i;
+
+ for (i = 0; i < model->num_objects; i++) {
+ if (polygon_contains_point (polygon, &model->objects[i].position))
+ polygon_reflect_object (polygon, &model->objects[i]);
+ }
+}
+
+static void
+model_constrain (Model *model)
{
double dx, dy, x, y, distance, fraction;
int i;
model->anchor_object->previous_position.y = model->anchor_position.y;
}
- /* FIXME: this should be "is point inside box" test instead. Figure
- * out from previous_position which edge the point has passed
- * through and reflect in that. */
- for (i = 0; i < model->num_objects; i++) {
- x = model->objects[i].position.x;
- y = model->objects[i].position.y;
- if (box_top - edge_fuzz <= y &&
- model->objects[i].previous_position.y <= box_top + edge_fuzz &&
- x < box_left) {
- model->objects[i].position.y = box_top - (y - box_top) * elasticity;
- model->objects[i].previous_position.y =
- box_top - (model->objects[i].previous_position.y - box_top) * elasticity;
- }
- }
-
- /* Ground collision detection constraints. This puts a ground level
- * in to make sure the points don't fall off the screen. */
- for (i = 0; i < model->num_objects; i++) {
- x = model->objects[i].position.x;
- y = model->objects[i].position.y;
-
- if (model->objects[i].position.y > ground_level) {
- model->objects[i].position.y =
- ground_level - (model->objects[i].position.y - ground_level) * elasticity;
- model->objects[i].previous_position.y =
- ground_level - (model->objects[i].previous_position.y - ground_level) * elasticity;
-
- /* Friction on impact */
- model->objects[i].position.x =
- model->objects[i].position.x * (1 - ground_friction) +
- model->objects[i].previous_position.x * ground_friction;
- }
- }
-
/* Offset constraints. */
for (i = 0; i < model->num_offsets; i++) {
x = (model->offsets[i].a->position.x + model->offsets[i].b->position.x) / 2;
model->sticks[i].b->position.x = x + dx * (1 - fraction);
model->sticks[i].b->position.y = y + dy * (1 - fraction);
}
+
+ /* Polygon constraints. */
+ for (i = 0; i < model->num_polygons; i++)
+ model_constrain_polygon (model, &model->polygons[i]);
}
static void
model_integrate (model, delta_t);
for (i = 0; i < 100; i++)
- model_constrain (model, delta_t);
+ model_constrain (model);
model->theta += delta_t;
}
}
static void
-draw_constraints (cairo_t *cr,
- Model *model,
- Color *color)
+draw_polygons (cairo_t *cr, Model *model, Color *color)
{
- cairo_set_source_rgba (cr, color->red, color->green, color->blue, 0.5);
-
- cairo_move_to (cr, 0, ground_level);
- cairo_line_to (cr, 1500, ground_level);
- cairo_line_to (cr, 1500, ground_level + 10);
- cairo_line_to (cr, 0, ground_level + 10);
- cairo_close_path (cr);
+ Polygon *p;
+ int i, j;
- cairo_move_to (cr, 0, box_top);
- cairo_line_to (cr, box_left, box_top);
- cairo_line_to (cr, box_left, box_bottom);
- cairo_line_to (cr, 0, box_bottom);
- cairo_close_path (cr);
+ for (i = 0; i < model->num_polygons; i++) {
+ p = &model->polygons[i];
+ cairo_set_source_rgba (cr, color->red, color->green, color->blue, 0.4);
+
+ for (j = 0; j < p->num_points; j++)
+ cairo_line_to (cr, p->points[j].x, p->points[j].y);
+ cairo_close_path (cr);
+ }
cairo_fill (cr);
+
}
static void
cairo_set_source_rgb (cr, 1, 1, 1);
cairo_paint (cr);
- draw_constraints (cr, closure->model, &red);
+ draw_polygons (cr, closure->model, &blue);
draw_sticks (cr, closure->model, &black);
draw_strings (cr, closure->model, &green);
draw_offsets (cr, closure->model, &blue);
timeout_callback (gpointer data)
{
Closure *closure = data;
- int i;
model_step (closure->model, 1);
closure.model = &model;
closure.frame_count = 0;
gettimeofday (&closure.start, NULL);
- g_timeout_add (40, timeout_callback, &closure);
+ g_timeout_add (50, timeout_callback, &closure);
gtk_main ();
return 0;
projects / akamaru / commitdiff