Doodle Blast! - Day 4 - Tweaks and More Flicks

Stats: 52 code files, 4588 lines of code, 2 textures, 20 sounds

Today was mostly about code clean up, bug hunting, and game play tweaks. The gist of the game was more-or-less there, but it wasn’t very playable yet and I wanted to spend some time tweaking details to make the game cuter. I was also starting to get a little tired and I needed to ease off just a touch.

One of the things I played with was flicking from the day before. You could flick the little soldiers into the air, but they looked very boring when they were falling down because I just applied a random rotation to them when they were released. So, I nixed that behavior and instead let them turn to follow the direction of their path, so that when they were falling down, they would do so head-first. And who doesn’t get a kick from seeing little stick figures falling head-first towards the ground???

I used the following method to turn a given sprite in the direction of the moving, underlying cpBody object:

cpVect direction = cpvnormalize(body->v);

float theta = -CC_RADIANS_TO_DEGREES(acosf(direction.x) * (direction.y > 0 ? 1.0f : -1.0f));

float currentAngle = sprite.rotation;

float dTheta = theta - currentAngle;

while (dTheta > 180) dTheta -= 360;
while (dTheta < -180) dTheta += 360;
sprite.rotation += fminf(DIRECTIONAL_MAX_THETA_DELTA, fmaxf(-DIRECTIONAL_MAX_THETA_DELTA, (dTheta * DIRECTIONAL_MOVE_FACTOR)));

Basically, the rotation of the sprite was attempting to conform to the velocity vector, but it did so over time with some easing-in baked in. The constants, in this case, were set to: DIRECTIONAL_MAX_THETA_DELTA = 5 (degrees) and DIRECTIONAL_MOVE_FACTOR = 0.3 (ie. 30%).

You will also notice that there are two types of runners here – the red ones, aka the suicide bombers, which don’t shoot but explode on contact and take away hit points, and the black ones that do shoot but don’t take any hit points when they crash into the tank (incidentally, I stole these pictures from Pop Fizz; that was before the final images were ready). The red peeps also had a count-down over them. Basically, they exploded when the count reached zero. In the final game, I cut that feature because it just polluted the UI and it didn’t really add that much more excitement to the game.

Doodle Blast! - Day 3 - Flicks

Stats: 52 code files, 4436 lines of code, 2 textures, 20 sounds

Today I introduced visual damage model on the player. Interestingly enough, most people playing Doodle Blast! for the first time completely miss it. I wanted to avoid having a health-meter bar or a number somewhere on the top of the screen, so I tried to solve this problem visually instead:

But as I said, most people miss it, so I might need to add a health bar after all.

The other big change in today’s build was the addition of flicking. Following the initial sketch of the game, I wanted to have little soldiers running around. I also wanted them to be flickable as flicking seems to be a popular gesture these days. The implementation was pretty simple.

Each soldier had a state variable, which could contain one of the following values:

• ATTACKING – the soldier is all gong-ho in trying to get the player
• GRABBED – the soldier is “grabbed” by a touch and is now following that touch around the screen
• FALLING – the touch that “grabbed” a soldier ended, and the soldier is now falling
• RECOVERING – the soldier hit the ground, but under some magic threshold speed. A timer has been set, after which the soldier will resume its attack.

To calculate how and whether a soldier was flicked after it was grabbed, I kept track of the movement of each touch. When I received a TouchMoved event, I used the last touch position along with the last touch time-stamp to compute the speed thusly:

touchSpeed = (currentLocation – lastLocation) / touchTimeDelta;

When the touch ended, I used the touchSpeed, clamped by some max value, and simply set the released soldier off in that direction.

This approach, however, created a problem. You suddenly couldn’t just shoot a soldier, because every touch near a soldier’s vicinity turned into a flick gesture. To solve this problem, I defined two constants: FLICK_TIME_EPSYLON and FLICK_DISTANCE_EPSYLON. If a given touch event took less time than FLICK_TIME_EPSYLON (0.3 secs) and if that touch event moved a total of less than FLICK_DISTANCE_EPSYLON (20 pixels), I wouldn’t consider that gesture a flick, but I would consider it a tap instead and still direct one of the guns to shoot at that location.

Finally, there was one more interesting change that I introduced the day before but didn’t get a chance to talk about yet. I wanted the tank and the stack of guns to feel like they are barely holding together as they clank along moving forward on a bumpy road. What I ended up doing was giving a random small impulse to the tank and to a random gun in the stack every 0 – 2 secs. You can see those bumps in the video from yesterday.