Method draw

samples/perlinTest/src/perlinTestApp.cpp:136–184

}

void perlinTestApp::draw()
{
#if defined( CINDER_LINUX ) || defined( CINDER_MAC )
	// On Linux/Mac, render to an image surface and then draw to window
	cairo::SurfaceImage surface( getWindowWidth(), getWindowHeight(), true );
	cairo::Context ctx( surface );
#else
	cairo::Context ctx( cairo::createWindowSurface() );
#endif
	ctx.copySurface( *mNoiseSurface, mNoiseSurface->getBounds() );

	// draw the gradient
	ctx.setSourceRgb( 1.0, 0.5, 0.25 );
	ctx.moveTo( mGradientPos );
	vec3 norm = mPerlin.dfBm( vec3( mGradientPos.x, mGradientPos.y, mTime ) * mFrequency ) * 20.0f;
	ctx.lineTo( mGradientPos.x + norm.x, mGradientPos.y + norm.y );
	ctx.stroke();	

	// draw gradient vector field
	if( mDrawLines ) {
		ctx.setLineWidth( 1.0f );
		ctx.setSourceRgba( 1.0, 1.0, 0.05, 0.25 );
		for( int y = 0; y < getWindowHeight(); y += 20 ) {
			for( int x = 0; x < getWindowWidth(); x += 20 ) {
				ctx.moveTo( vec2( x, y ) );
				vec3 norm = mPerlin.dfBm( vec3( x, y, mTime ) * mFrequency ) * 20.0f;
				if( mDrawNormalized ) {
					if( length2( vec2( norm.x, norm.y ) ) > 0 )
						ctx.lineTo( vec2( x, y ) + normalize( vec2( norm.x, norm.y ) ) * 20.0f );
				}
				else
					ctx.lineTo( vec2( x, y ) + vec2( norm.x, norm.y ) );
				/*float thisVal = mPerlin.fBm( vec3( x, y, mTime ) * mFrequency );
				float rightVal = mPerlin.fBm( vec3( x, y, mTime ) * mFrequency + vec3( 0.001f, 0, 0 ) );
				float downVal = mPerlin.fBm( vec3( x, y, mTime ) * mFrequency + vec3( 0, 0.001f, 0 ) );
				vec2 deriv = vec2( ( rightVal - thisVal ) / 0.001f, ( downVal - thisVal ) / 0.001f );
				ctx.lineTo( vec2( x, y ) + deriv.normalized() * 20.0f );*/
			}
		}
		ctx.stroke();
	}

#if defined( CINDER_LINUX ) || defined( CINDER_MAC )
	// Convert to Cinder surface and draw to window
	Surface8u cinderSurface = surface.getSurface();
	auto tex = gl::Texture2d::create( cinderSurface );
	gl::draw( tex );
#endif
}


#if defined( CINDER_LINUX ) || defined( CINDER_MAC )