From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Sat, 8 Mar 2014 16:57:33 +0000 (+0100)
Subject: Check for core OpenGL versions, not just extensions.
X-Git-Tag: 1.1~12^2~47
X-Git-Url: https://git.sesse.net/?p=movit;a=commitdiff_plain;h=cf3b8245a92407da567cf8843335911dd1a0da23

Check for core OpenGL versions, not just extensions.

Several extensions have been accepted over the years into the core OpenGL
spec, and occasionally, we might see a situation where something implements
the core spec but _not_ the extension. In particular, some extensions seem
to disappear when we ask Mesa for an OpenGL 3.1 forward-compatible context.
---

diff --git a/init.cpp b/init.cpp
index 944685c..3c781e1 100644
--- a/init.cpp
+++ b/init.cpp
@@ -284,32 +284,43 @@ void measure_roundoff_problems()
 bool check_extensions()
 {
 	// We fundamentally need FBOs and floating-point textures.
-	if (!epoxy_has_gl_extension("GL_ARB_framebuffer_object")) return false;
-	if (!epoxy_has_gl_extension("GL_ARB_texture_float")) return false;
+	// FBOs are covered by OpenGL 1.5, and are not an extension there.
+	// Floating-point textures are part of OpenGL 3.0 and newer.
+	if (epoxy_gl_version() < 15 &&
+	    !epoxy_has_gl_extension("GL_ARB_framebuffer_object")) return false;
+	if (epoxy_gl_version() < 30 &&
+	    !epoxy_has_gl_extension("GL_ARB_texture_float")) return false;
 
 	// We assume that we can use non-power-of-two textures without restrictions.
-	if (!epoxy_has_gl_extension("GL_ARB_texture_non_power_of_two")) return false;
+	if (epoxy_gl_version() < 20 &&
+	    !epoxy_has_gl_extension("GL_ARB_texture_non_power_of_two")) return false;
 
 	// We also need GLSL fragment shaders.
-	if (!epoxy_has_gl_extension("GL_ARB_fragment_shader")) return false;
-	if (!epoxy_has_gl_extension("GL_ARB_shading_language_100")) return false;
+	if (epoxy_gl_version() < 20) {
+		if (!epoxy_has_gl_extension("GL_ARB_fragment_shader")) return false;
+		if (!epoxy_has_gl_extension("GL_ARB_shading_language_100")) return false;
+	}
 
 	// FlatInput and YCbCrInput uses PBOs. (They could in theory do without,
 	// but no modern card would really not provide it.)
-	if (!epoxy_has_gl_extension("GL_ARB_pixel_buffer_object")) return false;
+	if (epoxy_gl_version() < 21 &&
+	    !epoxy_has_gl_extension("GL_ARB_pixel_buffer_object")) return false;
 
 	// ResampleEffect uses RG textures to encode a two-component LUT.
-	if (!epoxy_has_gl_extension("GL_ARB_texture_rg")) return false;
+	if (epoxy_gl_version() < 30 &&
+	    !epoxy_has_gl_extension("GL_ARB_texture_rg")) return false;
 
 	// sRGB texture decode would be nice, but are not mandatory
 	// (GammaExpansionEffect can do the same thing if needed).
-	movit_srgb_textures_supported = epoxy_has_gl_extension("GL_EXT_texture_sRGB");
+	movit_srgb_textures_supported =
+		(epoxy_gl_version() >= 21 || epoxy_has_gl_extension("GL_EXT_texture_sRGB"));
 
 	// We may want to use round() at the end of the final shader,
 	// if supported. We need either GLSL 1.30 or this extension to do that,
 	// and 1.30 brings with it other things that we don't want to demand
 	// for now.
-	movit_shader_rounding_supported = epoxy_has_gl_extension("GL_EXT_gpu_shader4");
+	movit_shader_rounding_supported =
+		(epoxy_gl_version() >= 30 || epoxy_has_gl_extension("GL_EXT_gpu_shader4"));
 
 	return true;
 }