Chipmunk Pro deformable terrain: DeformableBitmapDemo.m

DeformableBitmapDemo.m

#import "DeformableBitmapDemo.h"

@implementation DeformableBitmapDemo

@synthesize space;

#define PIXEL_SIZE 4
#define TILE_SIZE 128

- (id) init
{
	if((self = [super init])){
		space = [[ChipmunkSpace alloc] init];
		space.gravity = cpv(0, -500);
		
		int width = 640;
		int height = 480;
		
		// Subsample the data from a small context for efficiency.
		CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
		sampler = [[ChipmunkCGContextSampler alloc] initWithWidth:width/PIXEL_SIZE height:height/PIXEL_SIZE colorSpace:colorSpace bitmapInfo:kCGImageAlphaNone component:0];
		CGColorSpaceRelease(colorSpace);
		
		[sampler setBorderValue:1.0];
		
		// The output rectangle should be inset slightly so that we sample pixel centers, not edges.
		// This along with the tileOffset below will make sure the pixels line up with the geometry perfectly.
		sampler.outputRect = cpBBNew(0.5*PIXEL_SIZE, 0.5*PIXEL_SIZE, width - 0.5*PIXEL_SIZE, height - 0.5*PIXEL_SIZE);
		
		// Samples are spread out over the entire tile size starting at the edges.
		// You must sample 1 point more than you'd think to line up with the pixels.
		tiles = [[ChipmunkBasicTileCache alloc] initWithSampler:sampler space:space tileSize:TILE_SIZE samplesPerTile:TILE_SIZE/PIXEL_SIZE + 1];
		tiles.tileOffset = cpv(-0.5*PIXEL_SIZE, -0.5*PIXEL_SIZE); // See above
		tiles.segmentRadius = 1;
		tiles.simplifyThreshold = 2;
		
		// Set the CGContext's transform to match it's Chipmunk coords.
		CGContextConcatCTM(sampler.context, CGAffineTransformMake(1.0/PIXEL_SIZE, 0.0, 0.0, 1.0/PIXEL_SIZE, 0.0, 0.0));
		
		// Clear it to white.
		CGContextSetGrayFillColor(sampler.context, 1.0, 1.0);
		CGContextFillRect(sampler.context, CGRectMake(0, 0, width, height));
		
		// Draw a block in the middle of the screen.
		CGContextSetGrayFillColor(sampler.context, 0.0, 1.0);
		CGContextFillRect(sampler.context, CGRectMake(100, 100, width - 200, height - 200));
	}
	
	return self;
}

-(void)dealloc
{
	self.space = nil;
	
	[sampler release];
	[tiles release];
	
	[super dealloc];
}

static cpBB
CGRect2cpBB(CGRect r)
{
	cpFloat l = r.origin.x;
	cpFloat b = r.origin.y;
	return cpBBNew(l, b, l + r.size.width, b + r.size.height);
}

//static cpBB
//cpBBDilate(cpBB bb, cpFloat d)
//{
//	return cpBBNew(bb.l - d, bb.b - d, bb.r + d, bb.t + d);
//}

-(void)drawEllipseAt:(cpVect)pos
{
	cpFloat radius = 16;
	CGRect rect = CGRectMake(pos.x - radius, pos.y - radius, radius*2.0, radius*2.0);
	
	CGContextFillEllipseInRect(sampler.context, rect);
//	CGContextFillRect(sampler.context, rect);
	
	[tiles markDirtyRect:CGRect2cpBB(rect)];
}

-(void)leftMouse:(cpVect)pos;
{
	CGContextSetGrayFillColor(sampler.context, 1.0, 1.0);
	[self drawEllipseAt:pos];
}

-(void)drag:(cpVect)pos {
	[self drawEllipseAt:pos];
}

-(void)rightMouse:(cpVect)pos;
{
	CGContextSetGrayFillColor(sampler.context, 2.0, 1.0);
	[self drawEllipseAt:pos];
}

-(void)step:(cpFloat)dt;
{
	// Ensure that the geometry for the current screen rect is ready.
	[tiles ensureRect:cpBBNew(0.0, 0.0, 640.0, 480.0)];
	
	[space step:dt];
}

-(void)drawUnderlay
{
	glPixelZoom(PIXEL_SIZE, -PIXEL_SIZE);
	glWindowPos2f(0, 480);
	glDrawPixels(sampler.width, sampler.height, GL_LUMINANCE, GL_UNSIGNED_BYTE, [sampler.pixelData bytes]);
}

extern void ChipmunkDemoDrawString(int x, int y, const char *str);
-(void)drawOverlay
{
	ChipmunkDemoDrawString(20, 460,
		"Controls:\n"
		"Left click to cut holes in the block.\n"
		"Right click to add to it.\n"
		"Return to restart the demo.\n"
	);
}

@end