From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 5 Dec 2017 11:51:35 +0000 (+0200)
Subject: Check for maximum number of samples
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=c34da2dbd034cfe591e2020ef0b50265d0571fc5

Check for maximum number of samples

This makes it more apparent what the error is if a too large sample count
is requested.  Otherwise it would result in an "incomplete attachment"
error from the framebuffer object.
---

diff --git a/source/renderbuffer.cpp b/source/renderbuffer.cpp
index f146a915..5bea07fc 100644
--- a/source/renderbuffer.cpp
+++ b/source/renderbuffer.cpp
@@ -1,8 +1,11 @@
 #include <msp/gl/extensions/arb_direct_state_access.h>
 #include <msp/gl/extensions/ext_framebuffer_multisample.h>
 #include <msp/gl/extensions/ext_framebuffer_object.h>
+#include "misc.h"
 #include "renderbuffer.h"
 
+using namespace std;
+
 namespace Msp {
 namespace GL {
 
@@ -44,12 +47,21 @@ void Renderbuffer::storage(PixelFormat fmt, unsigned wd, unsigned ht)
 	}
 }
 
+unsigned Renderbuffer::get_max_samples()
+{
+	static unsigned max_samples = (EXT_framebuffer_multisample ? get_i(GL_MAX_SAMPLES) : 0);
+	return max_samples;
+}
+
 void Renderbuffer::storage_multisample(unsigned samples, PixelFormat fmt, unsigned wd, unsigned ht)
 {
 	if(!samples)
 		return storage(fmt, wd, ht);
 
 	static Require _req(EXT_framebuffer_multisample);
+	if(samples>get_max_samples())
+		throw out_of_range("Renderbuffer::storage_multisample");
+
 	fmt = normalize_format(fmt);
 	require_pixelformat(fmt);
 
diff --git a/source/renderbuffer.h b/source/renderbuffer.h
index 0ccf4967..751374bd 100644
--- a/source/renderbuffer.h
+++ b/source/renderbuffer.h
@@ -38,6 +38,10 @@ public:
 	/** Allocates storage for the renderbuffer. */
 	void storage(PixelFormat fmt, unsigned wd, unsigned ht);
 
+	/** Returns the maximum supported sample count for multisampling.  If
+	multisampling is not supported, returns 0. */
+	static unsigned get_max_samples();
+
 	/** Allocates multisample storage for the renderbuffer.  All attachments in
 	a framebuffer must have the same number of samples.  To transfer the
 	contents to a texture for furter processing, use the framebuffer blit