From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Wed, 12 Feb 2014 00:44:42 +0000 (+0100)
Subject: Make init_movit() return a true/false error value.
X-Git-Tag: 1.0~46
X-Git-Url: https://git.sesse.net/?p=movit;a=commitdiff_plain;h=0fa51e08f83e0283337216f5b951b3d5a8c0555b

Make init_movit() return a true/false error value.

This allows clients to programmatically enable/disable Movit usage
as needed on very old platforms.
---

diff --git a/demo.cpp b/demo.cpp
index 81d3e50..81bda2d 100644
--- a/demo.cpp
+++ b/demo.cpp
@@ -176,7 +176,7 @@ int main(int argc, char **argv)
 	SDL_SetVideoMode(WIDTH, HEIGHT, 0, SDL_OPENGL);
 	SDL_WM_SetCaption("OpenGL window", NULL);
 
-	init_movit(".", MOVIT_DEBUG_ON);
+	CHECK(init_movit(".", MOVIT_DEBUG_ON));
 	printf("GPU texture subpixel precision: about %.1f bits\n",
 		log2(1.0f / movit_texel_subpixel_precision));
 	printf("Wrongly rounded x+0.48 or x+0.52 values: %d/510\n",
diff --git a/init.cpp b/init.cpp
index d8d249f..fd22778 100644
--- a/init.cpp
+++ b/init.cpp
@@ -251,25 +251,25 @@ void measure_roundoff_problems()
 	check_error();
 }
 
-void check_extensions()
+bool check_extensions()
 {
 	// We fundamentally need FBOs and floating-point textures.
-	assert(glewIsSupported("GL_ARB_framebuffer_object") != 0);
-	assert(glewIsSupported("GL_ARB_texture_float") != 0);
+	if (!glewIsSupported("GL_ARB_framebuffer_object")) return false;
+	if (!glewIsSupported("GL_ARB_texture_float")) return false;
 
 	// We assume that we can use non-power-of-two textures without restrictions.
-	assert(glewIsSupported("GL_ARB_texture_non_power_of_two") != 0);
+	if (!glewIsSupported("GL_ARB_texture_non_power_of_two")) return false;
 
 	// We also need GLSL fragment shaders.
-	assert(glewIsSupported("GL_ARB_fragment_shader") != 0);
-	assert(glewIsSupported("GL_ARB_shading_language_100") != 0);
+	if (!glewIsSupported("GL_ARB_fragment_shader")) return false;
+	if (!glewIsSupported("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.)
-	assert(glewIsSupported("GL_ARB_pixel_buffer_object") != 0);
+	if (!glewIsSupported("GL_ARB_pixel_buffer_object")) return false;
 
 	// ResampleEffect uses RG textures to encode a two-component LUT.
-	assert(glewIsSupported("GL_ARB_texture_rg") != 0);
+	if (!glewIsSupported("GL_ARB_texture_rg")) return false;
 
 	// sRGB texture decode would be nice, but are not mandatory
 	// (GammaExpansionEffect can do the same thing if needed).
@@ -280,29 +280,37 @@ void check_extensions()
 	// and 1.30 brings with it other things that we don't want to demand
 	// for now.
 	movit_shader_rounding_supported = glewIsSupported("GL_EXT_gpu_shader4");
+
+	return true;
 }
 
 }  // namespace
 
-void init_movit(const string& data_directory, MovitDebugLevel debug_level)
+bool init_movit(const string& data_directory, MovitDebugLevel debug_level)
 {
 	if (movit_initialized) {
-		return;
+		return true;
 	}
 
 	movit_data_directory = new string(data_directory);
 	movit_debug_level = debug_level;
 
-	glewInit();
+	GLenum err = glewInit();
+	if (err != GLEW_OK) {
+		return false;
+	}
 
 	// geez	
 	glPixelStorei(GL_PACK_ALIGNMENT, 1);
 	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 	glDisable(GL_DITHER);
 
+	if (!check_extensions()) {
+		return false;
+	}
 	measure_texel_subpixel_precision();
 	measure_roundoff_problems();
-	check_extensions();
 
 	movit_initialized = true;
+	return true;
 }
diff --git a/init.h b/init.h
index 398ddbe..25869d1 100644
--- a/init.h
+++ b/init.h
@@ -1,6 +1,7 @@
 #ifndef _MOVIT_INIT_H
 #define _MOVIT_INIT_H
 
+#include "defs.h"
 #include <string>
 
 enum MovitDebugLevel {
@@ -10,7 +11,8 @@ enum MovitDebugLevel {
 
 // Initialize the library; in particular, will query the GPU for information
 // that is needed by various components. For instance, it verifies that
-// we have all the OpenGL extensions we need.
+// we have all the OpenGL extensions we need. Returns true if initialization
+// succeeded.
 //
 // The first parameter gives which directory to read .frag files from.
 // This is a temporary hack until we add something more solid.
@@ -20,8 +22,8 @@ enum MovitDebugLevel {
 // generated shaders to the current directory.
 //
 // If you call init_movit() twice with different parameters,
-// only the first will count.
-void init_movit(const std::string& data_directory, MovitDebugLevel debug_level);
+// only the first will count, and the second will always return true.
+bool init_movit(const std::string& data_directory, MovitDebugLevel debug_level) MUST_CHECK_RESULT;
 
 // GPU features. These are not intended for end-user use.
 
diff --git a/test_util.cpp b/test_util.cpp
index 59c0ef4..61c3918 100644
--- a/test_util.cpp
+++ b/test_util.cpp
@@ -47,7 +47,7 @@ EffectChainTester::EffectChainTester(const float *data, unsigned width, unsigned
                                      GLenum framebuffer_format)
 	: chain(width, height, get_static_pool()), width(width), height(height), finalized(false)
 {
-	init_movit(".", MOVIT_DEBUG_OFF);
+	CHECK(init_movit(".", MOVIT_DEBUG_OFF));
 
 	if (data != NULL) {
 		add_input(data, pixel_format, color_space, gamma_curve);