diff -r a4913301c626 -r 558fde7da82a src/sampler.cc
--- a/src/sampler.cc	Wed Mar 26 17:03:38 2008 +0100
+++ b/src/sampler.cc	Fri Mar 28 00:53:20 2008 +0100
@@ -36,10 +36,22 @@
 
 int DefaultSampler::initSampleSet()
 {
+	static const int gridsamples[] = {1,5,9,16};
+	const int samples = gridsamples[oversample];
 	if ( phase == 0 )
 	{
+		cout << "phase 1" << endl;
 		phase++;
-		return w*h;
+		return w*h*samples;
+	}
+	else if ( phase == 1 && oversample )
+	{
+		cout << "phase 2" << endl;
+		phase = -1;
+		Float *buf;
+		for (buf = buffer; buf != buffer + w*h*3; buf++)
+			*buf = *buf * (1.0/samples);
+		return 0;
 	}
 	else
 	{
@@ -51,31 +63,79 @@
 Sample* DefaultSampler::nextSample(Sample *prev)
 {
 	DefaultSample *s = new DefaultSample;
-	if (prev)
+
+	/* grid oversampling */
+	static const int gridsamples[] = {1,5,9,16};
+	static const Float osa5x[] = {0.0, -0.4, +0.4, +0.4, -0.4};
+	static const Float osa5y[] = {0.0, -0.4, -0.4, +0.4, +0.4};
+	static const Float osa9x[] = {-0.34,  0.00, +0.34,
+		-0.34,  0.00, +0.34, -0.34,  0.00, +0.34};
+	static const Float osa9y[] = {-0.34, -0.34, -0.34,
+			0.00,  0.00,  0.00, +0.34, +0.34, +0.34};
+	static const Float osa16x[] = {-0.375, -0.125, +0.125, +0.375,
+		-0.375, -0.125, +0.125, +0.375, -0.375, -0.125, +0.125, +0.375,
+		-0.375, -0.125, +0.125, +0.375};
+	static const Float osa16y[] = {-0.375, -0.375, -0.375, -0.375,
+		-0.125, -0.125, -0.125, -0.125, +0.125, +0.125, +0.125, +0.125,
+		+0.375, +0.375, +0.375, +0.375};
+	static const Float *osaSx[] = {NULL, osa5x, osa9x, osa16x};
+	static const Float *osaSy[] = {NULL, osa5y, osa9y, osa16y};
+	const int samples = gridsamples[oversample];
+	const Float *osax = osaSx[oversample];
+	const Float *osay = osaSy[oversample];
+
+	if (!prev)
 	{
-		DefaultSample *sp = static_cast<DefaultSample*>(prev);
-		s->sx = sp->sx + 1;
-		s->sy = sp->sy;
-		if (s->sx >= w)
-		{
-			s->sx = 0;
-			s->sy++;
-		}
-		if (s->sy >= h)
-		{
-			delete s;
-			return NULL;
-		}
-		s->x = (Float)s->sx/h - (Float)w/h/2.0;
-		s->y = (Float)s->sy/h - 0.5;
-	}
-	else
-	{
+		// first sample
 		s->x = -(Float)w/h/2.0;
 		s->y = -0.5;
 		s->sx = 0;
 		s->sy = 0;
+		s->osa_samp = 0;
 	}
+	else
+	{
+		DefaultSample *sp = static_cast<DefaultSample*>(prev);
+
+		s->osa_samp = sp->osa_samp + 1;
+
+		if (oversample && oversample <= 3 && s->osa_samp < samples)
+		{
+			s->sx = sp->sx;
+			s->sy = sp->sy;
+			s->x = osax[s->osa_samp]/h + (Float)s->sx/h - (Float)w/h/2.0;
+			s->y = osay[s->osa_samp]/h + (Float)s->sy/h - 0.5;
+		}
+		else
+		{
+			s->sx = sp->sx + 1;
+			s->sy = sp->sy;
+			if (s->sx >= w)
+			{
+				s->sx = 0;
+				s->sy++;
+			}
+			if (s->sy >= h)
+			{
+				delete s;
+				return NULL;
+			}
+			s->x = (Float)s->sx/h - (Float)w/h/2.0;
+			s->y = (Float)s->sy/h - 0.5;
+			s->osa_samp = 0;
+		}
+	}
+
+	if (s->osa_samp == 0 && oversample && oversample <= 3)
+	{
+		s->x += osax[0]/h;
+		s->y += osay[0]/h;
+		Float *buf = buffer + 3*(s->sy*w + s->sx);
+		*(buf++) = 0;
+		*(buf++) = 0;
+		*(buf++) = 0;
+	}
+
 	return s;
 }
 
@@ -83,8 +143,17 @@
 {
 	DefaultSample *sp = static_cast<DefaultSample*>(samp);
 	Float *buf = buffer + 3*(sp->sy*w + sp->sx);
-	*(buf++) = col.r;
-	*(buf++) = col.g;
-	*(buf++) = col.b;
+	if (oversample)
+	{
+		*(buf+0) += col.r;
+		*(buf+1) += col.g;
+		*(buf+2) += col.b;
+	}
+	else
+	{
+		*(buf++) = col.r;
+		*(buf++) = col.g;
+		*(buf++) = col.b;
+	}
 }