framerates on iphone « cocos2d for iPhone

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framerates on iphone

(8 posts) (4 voices)

Started 2 years ago by leesti
Latest reply from zombie

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leesti
Member

Hello,

First post this. I've been building on the simulator whilst developing my first game - using a scheduler at 60fps. Seems to run fine, but when building on the iphone, the game starts at 30fps, then seems to swap randomly between 30 and 60fps. It seems to (sometimes) eventually get to a consistent 60fps after maybe 30 seconds or so. The game is really doing nothing intensive, just a simple bouncing ball with a touch event at the moment, so it seems unlikely it would be too much to fit into 60fps.

Has anyone else experienced this? Seems almost like the iphone is doing some startup background tasks for some time after the game has started.

Any ideas?

Thanks

Posted 2 years ago #
zombie
Member

Try to use the FastDirector

Zombie - follow me on Twitter for some shocking news soons: http://twitter.com/ZombieSmash

Posted 2 years ago #
SonnyBurnette
Member

Off topic: @Zombie: what fonts are you using? They look great.

Posted 2 years ago #

Thanks for the suggestion. Using fastDirector increased the framerate by about 10fps, but its still slow (running at about 40-50fps on average. I've narrowed down the problem code to the following loop that is plotting stars for my starfield. When I have a total of 256 stars in the array, there's slowdown. If I reduce that number, its fine, running at a consistent 60fps: -

update function (called from schedule/tick):

// set rotation values (sinA, cosA, etc)
          ...
          ...
          ...

	// update each star
	NSEnumerator *enumerator = [stars objectEnumerator];
    Star *star;
    while ( star = [enumerator nextObject] ){

        // move star closer
		star.universeZ -= star.velocityZ * starVelocity;
		if( star.universeZ < STARFIELD_FIELD_MINZ ){
			[star resetRandom:NO];
		}

		// rotate Y
		star.rotationX = star.universeX * cosA + star.universeZ * sinA;
		star.rotationZ = star.universeZ * cosA - star.universeX * sinA;

		// rotate X
		star.rotationY = star.universeY * cosB + star.rotationZ * sinB;
		star.rotationZ = star.rotationZ * cosB - star.universeY * sinB;

		tempRotationX = star.rotationX * cosC + star.rotationY * sinC;
		star.rotationY = star.rotationY * cosC - star.rotationX * sinC;
		star.rotationX = tempRotationX;

		// calculate screen coordinates
		star.screenX = (CGFloat)screenCentreX + star.rotationX / star.rotationZ * screenZoom;
		star.screenY = (CGFloat)screenCentreY + star.rotationY / star.rotationZ * screenZoom;

		star.brightness = 180 - (180 * (star.universeZ / STARFIELD_FIELD_MAXZ));
    }

draw function:

// draw the starfield
    NSMutableArray *stars = starfield.stars;
    NSEnumerator *enumerator = [stars objectEnumerator];
    Star *star;
    while ( star = [enumerator nextObject] ){

		if( star.rotationZ > 1.0f && star.rotationZ < 640.0f ){
			if( (star.screenX > 2 && star.screenX < starfield.screenWidth + self.position.x) &&
				(star.screenY > 2 && star.screenY < (starfield.screenHeight + self.position.y)) ){

				glPointSize(1);
				glColor4ub(star.brightness,star.brightness,star.brightness,255);
				drawPoint( ccp(star.screenX, star.screenY) );
			}
		}
	}

Surely running this code on 256 stars is not gonna cause such a slowdown... or can anyone see any obvious mistakes in this code? I'm new to objective C so its possible I'm doing something incorrectly.

Thanks again

Posted 2 years ago #

Codemattic
Moderator

"Surely running this code on 256 stars is not gonna cause such a slowdown..."

Yeah it could. If you look at how the particle system nodes work - they are able to draw all their points in a single batched vertex array, not one-by-one. I think you are just coming up against the limits of the cpu/gpu. Try building a vertex array of 256 points and batch drawing that and see if it makes a difference. Good luck!

Posted 2 years ago #

leesti
Member

Thanks for the info. I've changed the code (see below) and now I can get up to around 1000 stars before I notice any slowdown :)

The only problem though is I'm not sure how to set the colour individually for each point, so right now all my stars are full brightness at any z-coord. I looked in the drawPrimitives example but couldn't see a way to set the colours in one go. Anyone have a clue how to do this? Here's the code: -

glPointSize(1);
	glColor4ub(128, 128, 128, 255);  // all points same brightness :(

	CGPoint verts[STARFIELD_NUM_STARS];
	int v = 0;

	NSEnumerator *enumerator = [starfield.stars objectEnumerator];
    Star *star;
    while ( star = [enumerator nextObject] ){
		if( star.rotationZ > 1.0f && star.rotationZ < 640.0f ){
			if( star.screenX > 1 && star.screenX < starfield.screenWidth &&
			   star.screenY > 1 && star.screenY < starfield.screenHeight ){

				verts[v] = ccp(star.screenX, star.screenY);

				// ideally I could do something like this
				// colours[v] = {star.brightness,star.brightness,star.brightness, 255 };

				v++;
			}
		}
	}
	drawPoints( verts, v );

	// is there something like this: ?
	// drawPoints( verts, colours, v );

Any help appreciated.

Thanks

Posted 2 years ago #

leesti
Member

OK, I fixed it. I added a drawColoredPoints() function, based on the current cocos2d drawPoints():

void drawColoredPoints( CGPoint *points, GLubyte *colors, unsigned int numberOfPoints )
{
	glVertexPointer(2, GL_FLOAT, 0, points);
	glEnableClientState(GL_VERTEX_ARRAY);

	glColorPointer(4, GL_UNSIGNED_BYTE, 0, colors);
	glEnableClientState(GL_COLOR_ARRAY);

	glDrawArrays(GL_POINTS, 0, numberOfPoints);

	glDisableClientState(GL_VERTEX_ARRAY);
	glDisableClientState(GL_COLOR_ARRAY);
}

Perhaps something like this could be built into the next version of cocos2d for iphone?

Posted 2 years ago #

zombie
Member

@ SonnyBurnette: Thanks! They are made by our graphics designer, I have no idea if he used a font for this or if its hand-drawn.

Zombie - follow me on Twitter for some shocking news soon: http://twitter.com/ZombieSmash

Posted 2 years ago #

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