Explicitly declare use of round() as an #extension.

round() is not part of GLSL 1.10, so we need to check explicitly for it
before we can use it.

Reported by Dan Dennedy.

diff --git a/demo.cpp b/demo.cpp
index b401f0574f21dcb904ac61dab1d854137838c510..81d3e5091909e5cae8afe2b36fbd6b6addb3edb3 100644 (file)
--- a/demo.cpp
+++ b/demo.cpp
@@ -181,6 +181,13 @@ int main(int argc, char **argv)
                log2(1.0f / movit_texel_subpixel_precision));
        printf("Wrongly rounded x+0.48 or x+0.52 values: %d/510\n",
                movit_num_wrongly_rounded);
                log2(1.0f / movit_texel_subpixel_precision));
        printf("Wrongly rounded x+0.48 or x+0.52 values: %d/510\n",
                movit_num_wrongly_rounded);

+       if (movit_num_wrongly_rounded > 0) {
+               if (movit_shader_rounding_supported) {
+                       printf("Rounding off in the shader to compensate.\n");
+               } else {
+                       printf("No shader roundoff available; cannot compensate.\n");
+               }
+       }

        
        unsigned img_w, img_h;
        unsigned char *src_img = load_image(argc > 1 ? argv[1] : "blg_wheels_woman_1.jpg", &img_w, &img_h);
        
        unsigned img_w, img_h;
        unsigned char *src_img = load_image(argc > 1 ? argv[1] : "blg_wheels_woman_1.jpg", &img_w, &img_h);

diff --git a/dither_effect.cpp b/dither_effect.cpp
index 14132bd43407bda72a7d2a8ca86f785bc9e1fab1..6e1ddd8d8ed4b7451698fd0b9d70382560bf0c52 100644 (file)
--- a/dither_effect.cpp
+++ b/dither_effect.cpp
@@ -45,7 +45,7 @@ DitherEffect::~DitherEffect()
 string DitherEffect::output_fragment_shader()
 {
        char buf[256];
 string DitherEffect::output_fragment_shader()
 {
        char buf[256];

-       sprintf(buf, "#define NEED_EXPLICIT_ROUND %d\n", (movit_num_wrongly_rounded > 0));
+       sprintf(buf, "#define NEED_EXPLICIT_ROUND %d\n", (movit_num_wrongly_rounded > 0 && movit_shader_rounding_supported));

        return buf + read_file("dither_effect.frag");
 }
 
        return buf + read_file("dither_effect.frag");
 }
 

diff --git a/header.frag b/header.frag
index 86c5730d2da831367d106ffe69b0033e114d7c75..af211fee6de53e2f02c5018d5ae5e59157117351 100644 (file)
--- a/header.frag
+++ b/header.frag
@@ -1 +1,6 @@
+#ifdef GL_EXT_gpu_shader4
+// We sometimes want round().
+#extension GL_EXT_gpu_shader4 : enable
+#endif
+

 varying vec2 tc;
 varying vec2 tc;

diff --git a/init.cpp b/init.cpp
index df72832e7b63985b50deb266db289d2ade015ef5..d8d249f256203decf638fb92febea1f44e758bdc 100644 (file)
--- a/init.cpp
+++ b/init.cpp
@@ -14,6 +14,7 @@ MovitDebugLevel movit_debug_level = MOVIT_DEBUG_ON;
 float movit_texel_subpixel_precision;
 bool movit_srgb_textures_supported;
 int movit_num_wrongly_rounded;
 float movit_texel_subpixel_precision;
 bool movit_srgb_textures_supported;
 int movit_num_wrongly_rounded;

+bool movit_shader_rounding_supported;

 
 // The rules for objects with nontrivial constructors in static scope
 // are somewhat convoluted, and easy to mess up. We simply have a
 
 // The rules for objects with nontrivial constructors in static scope
 // are somewhat convoluted, and easy to mess up. We simply have a


@@ -273,6 +274,12 @@ void check_extensions()
        // sRGB texture decode would be nice, but are not mandatory
        // (GammaExpansionEffect can do the same thing if needed).
        movit_srgb_textures_supported = glewIsSupported("GL_EXT_texture_sRGB");
        // sRGB texture decode would be nice, but are not mandatory
        // (GammaExpansionEffect can do the same thing if needed).
        movit_srgb_textures_supported = glewIsSupported("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 = glewIsSupported("GL_EXT_gpu_shader4");

 }
 
 }  // namespace
 }
 
 }  // namespace

diff --git a/init.h b/init.h
index 9b4deff5c7a36bb256b93ba199b5c8862c55f961..398ddbe647e82b0fb832f26882dfb521ec91aaef 100644 (file)
--- a/init.h
+++ b/init.h
@@ -51,9 +51,14 @@ extern float movit_texel_subpixel_precision;
 // round the right way (giving some leeway, but not a lot); the number
 // of errors are stored here.
 //
 // 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.
+// 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 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;
 
 // Whether the GPU in use supports GL_EXT_texture_sRGB.
 extern bool movit_srgb_textures_supported;