X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=init.h;h=628915d6a68882722847d0beb0c60e7ad80b024d;hp=e0dbe63688fff77225e45e4a162b2ad7cf1003df;hb=28bc5f37437fa8eaca523a209c558b807ced2db3;hpb=34f5f331bd3b643949ccbb0c3488af2823634d59

diff --git a/init.h b/init.h
index e0dbe63..628915d 100644
--- a/init.h
+++ b/init.h
@@ -1,21 +1,81 @@
-#ifndef _INIT_H
-#define _INIT_H
+#ifndef _MOVIT_INIT_H
+#define _MOVIT_INIT_H
+
+#include "defs.h"
+#include <string>
+
+namespace movit {
+
+enum MovitDebugLevel {
+	MOVIT_DEBUG_OFF = 0,
+	MOVIT_DEBUG_ON = 1,
+};
 
 // Initialize the library; in particular, will query the GPU for information
-// that is needed by various components. (In time, for instance, we will query
-// about extensions here.)
-void init_movit();
+// that is needed by various components. For instance, it verifies that
+// 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.
+//
+// The second parameter specifies whether debugging is on or off.
+// If it is on, Movit will write intermediate graphs and the final
+// generated shaders to the current directory.
+//
+// If you call init_movit() twice with different parameters,
+// 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.
 
 // Whether init_movit() has been called.
 extern bool movit_initialized;
 
-// An estimate on the number of different levels the linear texture interpolation
-// of the GPU can deliver. My Intel card seems to be limited to 2^6 levels here,
-// while a modern nVidia card (GTX 550 Ti) seem to use 2^8.
+// The current debug level.
+extern MovitDebugLevel movit_debug_level;
+
+// An estimate on the smallest values the linear texture interpolation
+// of the GPU can distinguish between, i.e., for a GPU with N-bit
+// texture subpixel precision, this value will be 2^-N.
 //
-// We currently don't bother to test above 2^10.
+// From reading the little specs that exist and through practical tests,
+// the broad picture seems to be that Intel cards have 6-bit precision,
+// nVidia cards have 8-bit, and Radeon cards have 6-bit before R6xx
+// (at least when not using trilinear sampling), but can reach
+// 8-bit precision on R6xx or newer in some (unspecified) cases.
+//
+// We currently don't bother to test for more than 1024 levels.
 extern float movit_texel_subpixel_precision;
 
-#endif  // !defined(_INIT_H)
+// Some GPUs use very inaccurate fixed-function circuits for rounding
+// floating-point values to 8-bit outputs, leading to absurdities like
+// the roundoff point between 128 and 129 being 128.62 instead of 128.6.
+// We test, for every integer, x+0.48 and x+0.52 and check that they
+// round the right way (giving some leeway, but not a lot); the number
+// of errors are stored here.
+//
+// If this value is above 0, the extension GL_EXT_gpu_shader4 is available
+// (giving round()) and you have enabled dithering, we will round off
+// explicitly at the very end of the shader.
+//
+// Note: I don't know of any cards that round off wrong (well, outside
+// our tolerance) and do not have this extension.
+extern int movit_num_wrongly_rounded;
+extern bool movit_shader_rounding_supported;
+
+// Whether the GPU in use supports GL_EXT_texture_sRGB.
+extern bool movit_srgb_textures_supported;
+
+// What shader model we are compiling for. This only affects the choice
+// of a few files (like header.frag); most of the shaders are the same.
+enum MovitShaderModel {
+	MOVIT_GLSL_110,
+	MOVIT_GLSL_130,
+	MOVIT_ESSL_300
+};
+extern MovitShaderModel movit_shader_model;
+
+}  // namespace movit
+
+#endif  // !defined(_MOVIT_INIT_H)