From 2303d6afc4a48adf3b7b8a309249b1f834808d42 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Fri, 13 Oct 2017 17:03:31 +0100
Subject: [PATCH] Cleaned up support for GL3 build

---
 include/osgText/Glyph                    |  9 -----
 src/osgPlugins/freetype/FreeTypeFont.cpp |  6 ++--
 src/osgText/DefaultFont.cpp              |  6 ++--
 src/osgText/Glyph.cpp                    | 44 ++++++++++++++++++------
 src/osgText/shaders/text_sdf_frag.cpp    | 18 +++++++---
 5 files changed, 51 insertions(+), 32 deletions(-)

diff --git a/include/osgText/Glyph b/include/osgText/Glyph
index 5dcfd12b3..adba880bc 100644
--- a/include/osgText/Glyph
+++ b/include/osgText/Glyph
@@ -30,15 +30,6 @@
 
 #include <OpenThreads/Mutex>
 
-// GL_ALPHA is deprecated in GL3/GL4 core profile, use GL_RED and a shader in this case. See osgText example.
-#if defined(OSG_GL3_AVAILABLE) && !defined(OSG_GL2_AVAILABLE) && !defined(OSG_GL1_AVAILABLE)
-#define OSGTEXT_GLYPH_FORMAT GL_RED
-#define OSGTEXT_GLYPH_INTERNALFORMAT GL_R8
-#else
-#define OSGTEXT_GLYPH_FORMAT GL_ALPHA
-#define OSGTEXT_GLYPH_INTERNALFORMAT GL_ALPHA
-#endif
-
 namespace osgText {
 
 class Font;
diff --git a/src/osgPlugins/freetype/FreeTypeFont.cpp b/src/osgPlugins/freetype/FreeTypeFont.cpp
index 323a874b6..d39f984c2 100644
--- a/src/osgPlugins/freetype/FreeTypeFont.cpp
+++ b/src/osgPlugins/freetype/FreeTypeFont.cpp
@@ -348,14 +348,12 @@ osgText::Glyph* FreeTypeFont::getGlyph(const osgText::FontResolution& fontRes, u
     for(unsigned char* p=data;p<data+dataSize;) { *p++ = 0; }
 
     glyph->setImage(width,height,1,
-                    OSGTEXT_GLYPH_INTERNALFORMAT,
-                    OSGTEXT_GLYPH_FORMAT, GL_UNSIGNED_BYTE,
+                    GL_ALPHA,
+                    GL_ALPHA, GL_UNSIGNED_BYTE,
                     data,
                     osg::Image::USE_NEW_DELETE,
                     1);
 
-    glyph->setInternalTextureFormat(OSGTEXT_GLYPH_INTERNALFORMAT);
-
     // copy image across to osgText::Glyph image.
     switch(glyphslot->bitmap.pixel_mode)
     {
diff --git a/src/osgText/DefaultFont.cpp b/src/osgText/DefaultFont.cpp
index cf3669cef..94aac9be3 100644
--- a/src/osgText/DefaultFont.cpp
+++ b/src/osgText/DefaultFont.cpp
@@ -207,14 +207,12 @@ void DefaultFont::constructGlyphs()
         for(unsigned char* p=data;p<data+dataSize;) { *p++ = 0; }
 
         glyph->setImage(sourceWidth,sourceHeight,1,
-                        OSGTEXT_GLYPH_INTERNALFORMAT,
-                        OSGTEXT_GLYPH_FORMAT, GL_UNSIGNED_BYTE,
+                        GL_ALPHA,
+                        GL_ALPHA, GL_UNSIGNED_BYTE,
                         data,
                         osg::Image::USE_NEW_DELETE,
                         1);
 
-        glyph->setInternalTextureFormat(OSGTEXT_GLYPH_INTERNALFORMAT);
-
         // now populate data array by converting bitmap into a luminance_alpha map.
         unsigned char* ptr = rasters[i-32];
         unsigned char value_on = 255;
diff --git a/src/osgText/Glyph.cpp b/src/osgText/Glyph.cpp
index 8ca21f5bc..114f6649a 100644
--- a/src/osgText/Glyph.cpp
+++ b/src/osgText/Glyph.cpp
@@ -28,6 +28,22 @@
 using namespace osgText;
 using namespace std;
 
+// GL_ALPHA and GL_LUMINANCE_ALPHA are deprecated in GL3/GL4 core profile, use GL_RED & GL_RB in this case.
+#if defined(OSG_GL3_AVAILABLE) && !defined(OSG_GL2_AVAILABLE) && !defined(OSG_GL1_AVAILABLE)
+#define OSGTEXT_GLYPH_ALPHA_FORMAT GL_RED
+#define OSGTEXT_GLYPH_ALPHA_INTERNALFORMAT GL_R8
+#define OSGTEXT_GLYPH_SDF_FORMAT GL_RG
+#define OSGTEXT_GLYPH_SDF_INTERNALFORMAT GL_RG8
+#else
+#define OSGTEXT_GLYPH_ALPHA_FORMAT GL_ALPHA
+#define OSGTEXT_GLYPH_ALPHA_INTERNALFORMAT GL_ALPHA
+#define OSGTEXT_GLYPH_SDF_FORMAT GL_LUMINANCE_ALPHA
+#define OSGTEXT_GLYPH_SDF_INTERNALFORMAT GL_LUMINANCE_ALPHA
+#endif
+
+
+
+
 #if 0
     #define TEXTURE_IMAGE_NUM_CHANNELS 1
     #define TEXTURE_IMAGE_FORMAT OSGTEXT_GLYPH_FORMAT
@@ -160,6 +176,9 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
     if (_glyphTextureFeatures==GREYSCALE)
     {
         // OSG_NOTICE<<"GlyphTexture::copyGlyphImage() greyscale copying. glyphTexture="<<this<<", glyph="<<glyph->getGlyphCode()<<std::endl;
+        // make sure the glyph image settings and the target image are consisent before copying.
+        glyph->setPixelFormat(_image->getPixelFormat());
+        glyph->setInternalTextureFormat(_image->getPixelFormat());
         _image->copySubImage(glyph->getTexturePositionX(), glyph->getTexturePositionY(), 0, glyph);
         return;
     }
@@ -185,8 +204,6 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
 
     float max_distance = sqrtf(float(search_distance)*float(search_distance)*2.0);
 
-    int num_channels = TEXTURE_IMAGE_NUM_CHANNELS;
-
     if ((left+glyph->getTexturePositionX())<0) left = -glyph->getTexturePositionX();
     if ((right+glyph->getTexturePositionX())>=dest_columns) right = dest_columns-glyph->getTexturePositionX()-1;
 
@@ -194,6 +211,12 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
     if ((upper+glyph->getTexturePositionY())>=dest_rows) upper = dest_rows-glyph->getTexturePositionY()-1;
 
 
+    int num_components = osg::Image::computeNumComponents(_image->getPixelFormat());
+    int bytes_per_pixel = osg::Image::computePixelSizeInBits(_image->getPixelFormat(),_image->getDataType())/8;
+    int alpha_offset = (_image->getPixelFormat()==GL_LUMINANCE_ALPHA) ? 1 : 0;
+    int sdf_offset = (_image->getPixelFormat()==GL_LUMINANCE_ALPHA) ? 0 : 1;
+
+
     unsigned char full_on = 255;
     unsigned char mid_point = full_on/2;
     float mid_point_f = float(mid_point)*multiplier;
@@ -343,14 +366,14 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
             }
 
 
-            unsigned char* dest_ptr = dest_data + (dr*dest_columns + dc)*num_channels;
-            if (num_channels==2)
+            unsigned char* dest_ptr = dest_data + (dr*dest_columns + dc)*bytes_per_pixel;
+            if (num_components==2)
             {
                 // signed distance field value
-                *(dest_ptr++) = value;
+                *(dest_ptr+sdf_offset) = value;
 
                 // original alpha value from glyph image
-                *(dest_ptr) = center_value;
+                *(dest_ptr+alpha_offset) = center_value;
             }
             else
             {
@@ -391,13 +414,12 @@ osg::Image* GlyphTexture::createImage()
 
         _image = new osg::Image;
 
-        #if defined(OSG_GL3_AVAILABLE) && !defined(OSG_GL2_AVAILABLE) && !defined(OSG_GL1_AVAILABLE)
-        GLenum imageFormat = (_glyphTextureFeatures==GREYSCALE) ? GL_RED : GL_RG;
-        #else
-        GLenum imageFormat = (_glyphTextureFeatures==GREYSCALE) ? GL_ALPHA : GL_LUMINANCE_ALPHA;
-        #endif
+        GLenum imageFormat = (_glyphTextureFeatures==GREYSCALE) ? OSGTEXT_GLYPH_ALPHA_FORMAT : OSGTEXT_GLYPH_SDF_FORMAT;
+        GLenum internalFormat = (_glyphTextureFeatures==GREYSCALE) ? OSGTEXT_GLYPH_ALPHA_INTERNALFORMAT : OSGTEXT_GLYPH_SDF_INTERNALFORMAT;
 
         _image->allocateImage(getTextureWidth(), getTextureHeight(), 1, imageFormat, GL_UNSIGNED_BYTE);
+        _image->setInternalTextureFormat(internalFormat);
+
         memset(_image->data(), 0, _image->getTotalSizeInBytes());
 
         for(GlyphRefList::iterator itr = _glyphs.begin();
diff --git a/src/osgText/shaders/text_sdf_frag.cpp b/src/osgText/shaders/text_sdf_frag.cpp
index 567e6a1bc..1864fc3c3 100644
--- a/src/osgText/shaders/text_sdf_frag.cpp
+++ b/src/osgText/shaders/text_sdf_frag.cpp
@@ -32,6 +32,16 @@ char text_sdf_frag[] = "$OSG_GLSL_VERSION\n"
                        "    #define osg_FragColor gl_FragColor\n"
                        "#endif\n"
                        "\n"
+                       "\n"
+                       "#if !defined(GL_ES) && __VERSION__>=130\n"
+                       "    #define ALPHA r\n"
+                       "    #define SDF g\n"
+                       "#else\n"
+                       "    #define ALPHA a\n"
+                       "    #define SDF r\n"
+                       "#endif\n"
+                       "\n"
+                       "\n"
                        "uniform sampler2D glyphTexture;\n"
                        "\n"
                        "$OSG_VARYING_IN vec2 texCoord;\n"
@@ -49,7 +59,7 @@ char text_sdf_frag[] = "$OSG_GLSL_VERSION\n"
                        "\n"
                        "float distanceFromEdge(vec2 tc)\n"
                        "{\n"
-                       "    float center_alpha = TEXTURELOD(glyphTexture, tc, 0.0).r;\n"
+                       "    float center_alpha = TEXTURELOD(glyphTexture, tc, 0.0).SDF;\n"
                        "    if (center_alpha==0.0) return -1.0;\n"
                        "\n"
                        "    //float distance_scale = (1.0/4.0)*1.41;\n"
@@ -169,7 +179,7 @@ char text_sdf_frag[] = "$OSG_GLSL_VERSION\n"
                        "\n"
                        "#ifdef OUTLINE\n"
                        "\n"
-                       "    float alpha = TEXTURE(glyphTexture, src_texCoord).a;\n"
+                       "    float alpha = TEXTURE(glyphTexture, src_texCoord).ALPHA;\n"
                        "    float delta_tc = 1.6*OUTLINE*GLYPH_DIMENSION/TEXTURE_DIMENSION;\n"
                        "\n"
                        "    float outline_alpha = alpha;\n"
@@ -184,7 +194,7 @@ char text_sdf_frag[] = "$OSG_GLSL_VERSION\n"
                        "    {\n"
                        "        for(float j=0.0; j<numSamples; ++j)\n"
                        "        {\n"
-                       "            float local_alpha = TEXTURE(glyphTexture, origin + vec2(i*delta_tc, j*delta_tc)).a;\n"
+                       "            float local_alpha = TEXTURE(glyphTexture, origin + vec2(i*delta_tc, j*delta_tc)).ALPHA;\n"
                        "            outline_alpha = max(outline_alpha, local_alpha);\n"
                        "            background_alpha = background_alpha * (1.0-local_alpha);\n"
                        "        }\n"
@@ -210,7 +220,7 @@ char text_sdf_frag[] = "$OSG_GLSL_VERSION\n"
                        "\n"
                        "#else\n"
                        "\n"
-                       "    float alpha = TEXTURE(glyphTexture, src_texCoord).a;\n"
+                       "    float alpha = TEXTURE(glyphTexture, src_texCoord).ALPHA;\n"
                        "    if (alpha==0.0) vec4(0.0, 0.0, 0.0, 0.0);\n"
                        "    return vec4(vertexColor.rgb, vertexColor.a * alpha);\n"
                        "\n"