Diff: game.cpp

Revision:

0:cf4396614a79

Child:

1:c18c231cb299

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/game.cpp	Fri Nov 03 18:48:48 2017 +0000
@@ -0,0 +1,158 @@
+#include "game.h"
+
+#include "globals.h"
+#include "physics.h"
+#include "wall.h"
+
+
+/** Erases the ball from the screen by drawing over it with the background color. */
+void erase_ball(Ball* ball)
+{
+    // TODO: Draw background color over curriously drawn ball location
+}
+
+/** Draws the ball on the screen at the updated location (according to the state) */
+void draw_ball(Ball* ball, Physics* state)
+{
+    // TODO: Save that updated ball position for later erasing
+    // TODO: Draw ball in its updated location
+}
+
+/** Reads inputs to the game, such as accelerometer and buttons */
+GameInputs read_inputs()
+{
+    GameInputs inputs = {0};
+
+    // TODO: Get acceleration vector from accelerometer
+    // TODO: Read buttons
+
+    return inputs;
+}
+
+int update_game(DLinkedList* arena, Physics* curr, GameInputs inputs, float delta)
+{
+    ///////////////////////////////
+    // Prepare for physics update
+    ///////////////////////////////
+    // Make a copy of the current state for modification
+    Physics next = *curr;
+    // No acceleration unless the ArenaElements apply them. (Newton's 1st law)
+    next.ax = next.ay = 0.0;
+
+    // Loop over all arena elements
+    ArenaElement* elem = (ArenaElement*)getHead(arena);
+    do {
+        switch(elem->type) {
+            case WALL:
+                do_wall(&next, curr, (Wall*) elem, delta);
+                break;
+            case BALL:
+                forward_euler(&next, delta);
+                break;
+            default:
+                break;
+        }
+    } while(elem = (ArenaElement*)getNext(arena));
+
+    // Last thing! Update state, so it will be saved for the next iteration.
+    *curr = next;
+    
+    // Zero means we aren't done yet
+    return 0;
+}
+
+int run_game(DLinkedList* arena, Physics* state)
+{
+    // Initialize game loop timers
+    int tick, phys_tick, draw_tick;
+    Timer timer;
+    timer.start();
+    tick = timer.read_ms();
+    phys_tick = tick;
+    draw_tick = tick;
+
+    // Initialize debug counters
+    int count = 0;
+    int count2 = 0;
+
+    // Initial draw of the game
+    uLCD.background_color(BLACK);
+    uLCD.cls();
+
+    ///////////////////
+    // Main game loop
+    ///////////////////
+    while(1) {
+        // Read timer to determine how long the last loop took
+        tick = timer.read_ms();
+        
+        ///////////////////
+        // Physics Update
+        ///////////////////
+        // Rate limit: 1 ms
+        if (tick - phys_tick < 1) continue;
+        phys_tick = tick;
+
+        // Compute elapsed time in milliseconds
+        float delta = (tick-phys_tick)*1e-3;
+
+        // Read inputs
+        GameInputs inputs = read_inputs();
+
+        // Update game state
+        int done = update_game(arena, state, inputs, delta);
+        if (done) return done;
+
+        // Debug: Count physics updates
+        count2++;
+
+        //////////////////
+        // Render update
+        //////////////////
+        // Rate limit: 40ms
+        if(tick - draw_tick < 40) continue;
+        draw_tick = tick;
+
+        // Erase moving stuff
+        ArenaElement* elem = (ArenaElement*)getHead(arena);
+        do {
+            switch(elem->type) {
+                case BALL:
+                    erase_ball((Ball*) elem);
+                    break;
+                default: break;
+            }
+        } while(elem = (ArenaElement*)getNext(arena));
+
+        // Draw everything
+        elem = (ArenaElement*)getHead(arena);
+        do {
+            switch(elem->type) {
+                case WALL:
+                    draw_wall((Wall*) elem);
+                    break;
+                case BALL:
+                    draw_ball((Ball*) elem, state);
+                    break;
+                default:
+                    break;
+            }
+        } while(elem = (ArenaElement*)getNext(arena));
+
+        ///////////////
+        // Debug info
+        ///////////////
+        // Displays rate info in the top corner
+        //  First number is total time to update and render this frame
+        //  Second number is how many physics iterations between drawing frames
+        //  Only displayed every 10th render update (roughly 2.5 Hz)
+        // TODO: Take this out before you turn your code in!
+        if ((count = (count+1)%10) == 0) {
+            uLCD.locate(0, 0);
+            uLCD.printf("%d %d \r\n", timer.read_ms()-tick, count2);
+        }
+        
+        // Reset physics iteration counter after every render update
+        count2 = 0;
+    }
+}
\ No newline at end of file