screen rotation

game.c

@@ -17,7 +17,13 @@
 void
 draw_background(struct s_game *g) {
 	int face;
+	void (*drawer)(struct s_game *, int faceno, int dist, int thick, int col);
+
+	drawer = get_polygon_drawer(g);
+
 	for(face = 0; face < g->polygon_type; face++) {
+		drawer(g, face, POLYGON_SIZE, SCREEN_DIAGONAL,
+		       g->color * ((face%2)+1) / 4);
 	}
 }
 
@@ -38,6 +44,24 @@ get_circle_vertice(int angle, int dist) { //{{{
 
 	return p;
 } //}}}
+
+SDL_Point
+to_screen_coords(struct s_game *g, SDL_Point p) {
+	SDL_Point q;
+
+	p.x -= SCREEN_WIDTH/2;
+	p.y -= SCREEN_HEIGHT/2;
+	float angle = TO_RAD(g->general_rotation);
+
+	q.x = p.x * cos(angle) - p.y * sin(angle);
+	q.y = p.x * sin(angle) + p.y * cos(angle);
+
+	q.x += SCREEN_WIDTH/2;
+	q.y += SCREEN_HEIGHT/2;
+
+	return q;
+}
+
 void
 draw_cursor(struct s_game *g) { //{{{
 	SDL_Point p1, p2, p3;
@@ -46,7 +70,9 @@ draw_cursor(struct s_game *g) { //{{{
 	p2 = get_circle_vertice(g->cursor_angle-TO_DEG(8), CURSOR_DIST-10);
 	p3 = get_circle_vertice(g->cursor_angle+TO_DEG(8), CURSOR_DIST-10);
 
-	SDL_Point pts[3] = {p1, p2, p3};
+	SDL_Point pts[3] = {to_screen_coords(g, p1),
+	                    to_screen_coords(g, p2),
+	                    to_screen_coords(g, p3)};
 
 	SDL_FillPolygon(g->screen, pts, 3, g->color);
 } //}}}
@@ -65,12 +91,12 @@ void
 
 void
 draw_game(struct s_game *g) { //{{{
+	draw_background(g);
 	draw_polygon(g);
 	draw_obstacles(g);
 	draw_cursor(g);
 } //}}}
 
-
 void
 get_keys(struct s_game *g) { //{{{
 	SDL_PumpEvents();
@@ -92,6 +118,7 @@ void
 init_game(struct s_game *g) { //{{{
 	g->polygon_type = SHAPE_HEXAGON;
 	g->cursor_angle = TO_DEG(90);
+	g->general_rotation = 0;
 	g->color = 128;
 	g->keys = SDL_GetKeyState(NULL);
 

game.h

@@ -8,10 +8,11 @@
 #define GAME_H
 
 #include "SDL/SDL.h"
+#include "SDL_prims.h"
 
 #define SCREEN_WIDTH 640
 #define SCREEN_HEIGHT 480
-#define SCREEN_DIAGONAL (sqrt(SCREEN_HEIGHT*SCREEN_HEIGHT + SCREEN_WIDTH*SCREEN_WIDTH)/2)
+#define SCREEN_DIAGONAL (sqrt(SCREEN_HEIGHT*SCREEN_HEIGHT + SCREEN_WIDTH*SCREEN_WIDTH))
 
 
 #define POLYGON_SIZE 30
@@ -26,6 +27,7 @@
 
 #define OFFSET_POINT(p) {p.x += SCREEN_WIDTH/2; p.y += SCREEN_HEIGHT/2;}
 #define TO_DEG(x) (x*ANGLE_MAX/360)
+#define TO_RAD(x) (x * 2 * M_PI / ANGLE_MAX)
 
 
 struct s_obstacle {
@@ -39,6 +41,7 @@ struct s_obstacle {
 struct s_game {
 	#define CURSOR_POS_MAX 255
 	int cursor_angle; //relative to the polygon center's referential
+	int general_rotation;
 	int polygon_type; //Shape
 	int color;
 	int actual_speed;
@@ -65,6 +68,9 @@ void
 (*get_polygon_drawer(struct s_game *g))
 (struct s_game *, int faceno, int dist, int thick, int col);
 
+SDL_Point
+to_screen_coords(struct s_game *g, SDL_Point p);
+
 void
 draw_game(struct s_game *g);
 

main.c

@@ -25,9 +25,12 @@ start:
 	struct s_obstacle a = create_obstacle(SHAPE_THICK, 2, 1);
 	add_obstacle(&ga, a);
 
+
+	int rotation = 0;
+
 	while(1) {
 		SDL_FillRect(ga.screen, NULL, 0);
-		if(!(ga.counter % 50)) {
+		if(!(ga.counter % 30)) {
 			add_random_obstacle(&ga);
 		}
 		update_obstacles(&ga);
@@ -45,6 +48,16 @@ start:
 		SDL_Delay(5);
 
 		ga.counter++;
+
+		if(rand()%30 == 0) {
+			rotation += rand()%20 - 10;
+			if(rotation > 10)
+				rotation = 10;
+			if(rotation < -10)
+				rotation = -10;
+		}
+		ga.general_rotation += rotation;
+		ga.general_rotation %= ANGLE_MAX;
 	}
 
 	return EXIT_SUCCESS;

polygons.c

@@ -14,7 +14,7 @@
 #include "SDL/SDL.h"
 
 SDL_Point
-get_hexagon_vertice(int faceno, int dist) { //{{{
+get_hexagon_vertice(struct s_game *g, int faceno, int dist) { //{{{
 	SDL_Point p1;
 
 	p1.x = dist * cos((M_PI/3)*faceno);
@@ -28,12 +28,15 @@ void
 draw_hexagon_side(struct s_game *g, int faceno, int dist, int thick, int col) { //{{{
 	SDL_Point p1, p2, p3, p4;
 
-	p1 = get_hexagon_vertice(faceno, dist);
-	p2 = get_hexagon_vertice(faceno+1, dist);
-	p3 = get_hexagon_vertice(faceno+1, dist+thick);
-	p4 = get_hexagon_vertice(faceno, dist+thick);
+	p1 = get_hexagon_vertice(g, faceno, dist);
+	p2 = get_hexagon_vertice(g, faceno+1, dist);
+	p3 = get_hexagon_vertice(g, faceno+1, dist+thick);
+	p4 = get_hexagon_vertice(g, faceno, dist+thick);
 
-	SDL_Point points[4] = {p1, p2, p3, p4} ;
+	SDL_Point points[4] = {to_screen_coords(g, p1),
+	                       to_screen_coords(g, p2),
+	                       to_screen_coords(g, p3),
+	                       to_screen_coords(g, p4)} ;
 	SDL_FillPolygon(g->screen, points, 4, col);
 }//}}}
 void