Fix T37810: GLSL dither shader not working on OS X.

The GLSL function textureSize() is not supported here, only when we start using
OpenGL core profile will this work. For now check the supported GLSL version and
use a somewhat slower replacement.

2 files changed, 54 insertions, 5 deletions

diff --git a/intern/opencolorio/gpu_shader_display_transform.glsl b/intern/opencolorio/gpu_shader_display_transform.glsl
index 8a85d6cbffe..5921d6d9c73 100644
--- a/intern/opencolorio/gpu_shader_display_transform.glsl
+++ b/intern/opencolorio/gpu_shader_display_transform.glsl
@@ -1,11 +1,15 @@
 uniform sampler2D image_texture;
 uniform sampler3D lut3d_texture;
-uniform bool predivide;
 
 #ifdef USE_DITHER
 uniform float dither;
 #endif
 
+#ifdef USE_TEXTURE_SIZE
+uniform float image_texture_width;
+uniform float image_texture_height;
+#endif
+
 #ifdef USE_CURVE_MAPPING
 /* Curve mapping parameters
  *
@@ -115,7 +119,11 @@ float dither_random_value(vec2 co)
 vec2 round_to_pixel(vec2 st)
 {
 	vec2 result;
+#ifdef USE_TEXTURE_SIZE
+	vec2 size = vec2(image_texture_width, image_texture_height);
+#else
 	vec2 size = textureSize(image_texture, 0);
+#endif
 	result.x = float(int(st.x * size.x)) / size.x;
 	result.y = float(int(st.y * size.y)) / size.y;
 	return result;
@@ -139,12 +147,15 @@ void main()
 #ifdef USE_CURVE_MAPPING
 	col = curvemapping_evaluate_premulRGBF(col);
 #endif
-	if (predivide && col[3] > 0.0 && col[3] < 1.0) {
+
+#ifdef USE_PREDIVIDE
+	if (col[3] > 0.0 && col[3] < 1.0) {
 		float inv_alpha = 1.0 / col[3];
 		col[0] *= inv_alpha;
 		col[1] *= inv_alpha;
 		col[2] *= inv_alpha;
 	}
+#endif
 
 	/* NOTE: This is true we only do de-premul here and NO premul
 	 *       and the reason is simple -- opengl is always configured
diff --git a/intern/opencolorio/ocio_impl_glsl.cc b/intern/opencolorio/ocio_impl_glsl.cc
index 3a23c266345..677be0bf9ed 100644
--- a/intern/opencolorio/ocio_impl_glsl.cc
+++ b/intern/opencolorio/ocio_impl_glsl.cc
@@ -71,6 +71,10 @@ typedef struct OCIO_GLSLDrawState {
 	GLuint curve_mapping_texture;
 	size_t curve_mapping_cache_id;
 
+	bool predivide_used;
+
+	bool texture_size_used;
+
 	/* Cache */
 	std::string lut3dcacheid;
 	std::string shadercacheid;
@@ -221,6 +225,17 @@ bool OCIOImpl::supportGLSLDraw()
 	return GLEW_VERSION_2_0 && (GLEW_VERSION_3_0 || GLEW_ARB_texture_float);
 }
 
+static bool supportGLSL13()
+{
+	const char *version = (const char*)glGetString(GL_SHADING_LANGUAGE_VERSION);
+	int major = 1, minor = 0;
+
+	if (version && sscanf(version, "%d.%d", &major, &minor) == 2)
+		return (major > 1 || (major == 1 && minor >= 30));
+
+	return false;
+}
+
 /**
  * Setup OpenGL contexts for a transform defined by processor using GLSL
  * All LUT allocating baking and shader compilation happens here.
@@ -233,7 +248,7 @@ bool OCIOImpl::supportGLSLDraw()
  */
 bool OCIOImpl::setupGLSLDraw(OCIO_GLSLDrawState **state_r, OCIO_ConstProcessorRcPtr *processor,
                              OCIO_CurveMappingSettings *curve_mapping_settings,
-                             float dither, bool predivide)
+                             float dither, bool use_predivide)
 {
 	ConstProcessorRcPtr ocio_processor = *(ConstProcessorRcPtr *) processor;
 	bool use_curve_mapping = curve_mapping_settings != NULL;
@@ -302,6 +317,7 @@ bool OCIOImpl::setupGLSLDraw(OCIO_GLSLDrawState **state_r, OCIO_ConstProcessorRc
 	std::string shaderCacheID = ocio_processor->getGpuShaderTextCacheID(shaderDesc);
 	if (state->program == 0 ||
 	    shaderCacheID != state->shadercacheid ||
+	    use_predivide != state->predivide_used ||
 	    use_curve_mapping != state->curve_mapping_used ||
 	    use_dither != state->dither_used)
 	{
@@ -317,7 +333,17 @@ bool OCIOImpl::setupGLSLDraw(OCIO_GLSLDrawState **state_r, OCIO_ConstProcessorRc
 
 		std::ostringstream os;
 
-		os << "#version 130\n";
+		if (supportGLSL13()) {
+			os << "#version 130\n";
+		}
+		else {
+			os << "#define USE_TEXTURE_SIZE\n";
+			state->texture_size_used = use_dither;
+		}
+
+		if (use_predivide) {
+			os << "#define USE_PREDIVIDE\n";
+		}
 
 		if (use_dither) {
 			os << "#define USE_DITHER\n";
@@ -338,6 +364,7 @@ bool OCIOImpl::setupGLSLDraw(OCIO_GLSLDrawState **state_r, OCIO_ConstProcessorRc
 
 		state->curve_mapping_used = use_curve_mapping;
 		state->dither_used = use_dither;
+		state->predivide_used = use_predivide;
 	}
 
 	if (state->program) {
@@ -355,7 +382,18 @@ bool OCIOImpl::setupGLSLDraw(OCIO_GLSLDrawState **state_r, OCIO_ConstProcessorRc
 
 		glUniform1i(glGetUniformLocation(state->program, "image_texture"), 0);
 		glUniform1i(glGetUniformLocation(state->program, "lut3d_texture"), 1);
-		glUniform1i(glGetUniformLocation(state->program, "predivide"), predivide);
+
+		if (state->texture_size_used) {
+			/* we use textureSize() if possible for best performance, if not
+			 * supported we query the size and pass it as uniform variables */
+			GLint width, height;
+
+			glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &width);
+			glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, &height);
+
+			glUniform1f(glGetUniformLocation(state->program, "image_texture_width"), (float)width);
+			glUniform1f(glGetUniformLocation(state->program, "image_texture_height"), (float)height);
+		}
 
 		if (use_dither) {
 			glUniform1f(glGetUniformLocation(state->program, "dither"), dither);