Add a switch that controls the movement in the demo

See #9

include/arg_parser.h

@@ -29,10 +29,17 @@ extern unsigned g_max_iterations;
 extern char g_mesh_file[256];
 // defines the max and min values of random rotation bias
 extern float rand_min;
-// random rotation biases - the higher, the faster the rotation around x, y, 
+// random rotation biases - the higher, the faster the rotation around x, y,
 extern float random_bias_x;
 extern float random_bias_y;
 extern float random_bias_z;
 extern bool render_from_file;
+// controls whether the cube bounces around the screen
+// 0 = keep the cube centered, N (!= 0) = change direction every N frames
+extern unsigned g_bounce_every;
+// how many pixels to move per frame along x, y, z axes
+extern int g_move_x;
+extern int g_move_y;
+extern int g_move_z;
 
 void arg_parse(int argc, char** argv);

main.c

@@ -37,14 +37,16 @@ int main(int argc, char** argv) {
     for (size_t t = 0; t < g_max_iterations; ++t) {
         if (g_use_random_rotation)
             obj_mesh_rotate_to(shape, amplitude_x*sin(random_rot_speed_x*sin(random_rot_speed_x*t) + 2*random_bias_x),
-                                   amplitude_y*sin(random_rot_speed_y*random_bias_y*t           + 2*random_bias_y),
-                                   amplitude_z*sin(random_rot_speed_z*random_bias_z*t           + 2*random_bias_z));
+                                      amplitude_y*sin(random_rot_speed_y*random_bias_y*t           + 2*random_bias_y),
+                                      amplitude_z*sin(random_rot_speed_z*random_bias_z*t           + 2*random_bias_z));
         else
             obj_mesh_rotate_to(shape, g_rot_speed_x/20*t, g_rot_speed_y/20*t, g_rot_speed_z/20*t);
-        if ((t % 100) >= 50)
-            obj_mesh_translate_by(shape, 1, 1, 1);
-        else
-            obj_mesh_translate_by(shape, -1, -1, -1);
+		if (g_bounce_every != 0) {
+			if ((t % (2*g_bounce_every)) >= g_bounce_every)
+				obj_mesh_translate_by(shape, g_move_x, g_move_y, g_move_z);
+			else
+				obj_mesh_translate_by(shape, -g_move_x, -g_move_y, -g_move_z);
+		}
         render_write_shape(shape);
         render_flush();
 #ifndef _WIN32

src/arg_parser.c

@@ -31,12 +31,18 @@ unsigned g_max_iterations = UINT_MAX;
 char g_mesh_file[256] = {'\0'};
 // defines the max and min values of random rotation bias
 float rand_min = 0.75, rand_max = 2.25;
-// random rotation biases - the higher, the faster the rotation around x, y, 
+// random rotation biases - the higher, the faster the rotation around x, y,
 float random_bias_x = 0;
 float random_bias_y = 0;
 float random_bias_z = 0;
 bool render_from_file = false;
 
+unsigned g_bounce_every = 0;
+// how many pixels to move per frame along x, y, z axes
+int g_move_x = 2;
+int g_move_y = 1;
+int g_move_z = 1;
+
 
 void arg_parse(int argc, char** argv) {
     // initialise pseudo randomness generator for random rotations
@@ -84,6 +90,14 @@ void arg_parse(int argc, char** argv) {
             i++;
             strcpy(g_mesh_file, argv[i]);
             render_from_file = true;
+        } else if ((strcmp(argv[i], "--bounce") == 0) || (strcmp(argv[i], "-b") == 0)) {
+            g_bounce_every = atoi(argv[++i]);
+        } else if ((strcmp(argv[i], "--movex") == 0) || (strcmp(argv[i], "-mx") == 0)) {
+            g_move_x = atoi(argv[++i]);
+        } else if ((strcmp(argv[i], "--movey") == 0) || (strcmp(argv[i], "-my") == 0)) {
+            g_move_y = atoi(argv[++i]);
+        } else if ((strcmp(argv[i], "--movez") == 0) || (strcmp(argv[i], "-mz") == 0)) {
+            g_move_z = atoi(argv[++i]);
         } else {
             printf("Uknown option: %s\n", argv[i++]);
         }