X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=init.h;h=9b4deff5c7a36bb256b93ba199b5c8862c55f961;hp=a1e71dd54053b3f168f3c47267eba1512bd2096b;hb=18fdebc534adc6b7a4c36b290b01d598bcb671bc;hpb=38fca90c6ffde05e3459c7021e823cef0b3b27ac

diff --git a/init.h b/init.h
index a1e71dd..9b4deff 100644
--- a/init.h
+++ b/init.h
@@ -1,24 +1,61 @@
-#ifndef _INIT_H
-#define _INIT_H
+#ifndef _MOVIT_INIT_H
+#define _MOVIT_INIT_H
+
+#include <string>
+
+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. For instance, it verifies that
 // we have all the OpenGL extensions we need.
-void init_movit();
+//
+// 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.
+void init_movit(const std::string& data_directory, MovitDebugLevel debug_level);
 
 // 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.
+//
+// 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 above 2^10.
+// We currently don't bother to test for more than 1024 levels.
 extern float movit_texel_subpixel_precision;
 
+// 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, and you have enabled dithering, we will
+// round off explicitly at the very end of the shader.
+extern int movit_num_wrongly_rounded;
+
 // Whether the GPU in use supports GL_EXT_texture_sRGB.
 extern bool movit_srgb_textures_supported;
 
-#endif  // !defined(_INIT_H)
+#endif  // !defined(_MOVIT_INIT_H)