From c7711fd2d4a93daea340573d98687b9f01df574a Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Sat, 18 Mar 2017 18:08:12 +0000
Subject: [PATCH] Added support for GL3/GLES3, GL2,GLE2 shaders to
 osgText::Font/Text.

---
 src/osgText/Font.cpp   | 89 +++++++++++++++++++++++++++++++++++++++++-
 src/osgText/Text3D.cpp | 14 ++++++-
 2 files changed, 100 insertions(+), 3 deletions(-)

diff --git a/src/osgText/Font.cpp b/src/osgText/Font.cpp
index b57d844b1..7620724d9 100644
--- a/src/osgText/Font.cpp
+++ b/src/osgText/Font.cpp
@@ -34,6 +34,67 @@ using namespace std;
 
 static osg::ApplicationUsageProxy Font_e0(osg::ApplicationUsage::ENVIRONMENTAL_VARIABLE,"OSG_TEXT_INCREMENTAL_SUBLOADING <type>","ON | OFF");
 
+#define FIXED_FUNCTION defined(OSG_GL_FIXED_FUNCTION_AVAILABLE)
+#define SHADERS_GL3 (defined(OSG_GL3_AVAILABLE) || defined(OSG_GLES3_AVAILABLE))
+#define SHADERS_GL2 !FIXED_FUNCTION && !SHADERS_GL3
+
+
+#if SHADERS_GL3
+static const char* gl3_TextVertexShader = {
+    "#version 330 core\n"
+    "in vec4 osg_Vertex;\n"
+    "in vec4 osg_Color;\n"
+    "in vec4 osg_MultiTexCoord0;\n"
+    "uniform mat4 osg_ModelViewProjectionMatrix;\n"
+    "out vec2 texCoord;\n"
+    "out vec4 vertexColor;\n"
+    "void main(void)\n"
+    "{\n"
+    "    gl_Position = osg_ModelViewProjectionMatrix * osg_Vertex;\n"
+    "    texCoord = osg_MultiTexCoord0.xy;\n"
+    "    vertexColor = osg_Color; \n"
+    "}\n"
+};
+
+static const char* gl3_TextFragmentShader = {
+    "#version 330 core\n"
+    "uniform sampler2D glyphTexture;\n"
+    "in vec2 texCoord;\n"
+    "in vec4 vertexColor;\n"
+    "out vec4 color;\n"
+    "void main(void)\n"
+    "{\n"
+    "    if (texCoord.x>=0.0) color = vertexColor * vec4(1.0, 1.0, 1.0, texture(glyphTexture, texCoord).r);\n"
+    "    else color = vertexColor;\n"
+    "}\n"
+};
+
+#endif
+
+
+#if SHADERS_GL2
+static const char* gl2_TextVertexShader = {
+    "varying vec2 texCoord;\n"
+    "varying vec4 vertexColor;\n"
+    "void main(void)\n"
+    "{\n"
+    "    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
+    "    texCoord = gl_MultiTexCoord0.xy;\n"
+    "    vertexColor = gl_Color; \n"
+    "}\n"
+};
+
+static const char* gl2_TextFragmentShader = {
+    "uniform sampler2D glyphTexture;\n"
+    "varying vec2 texCoord;\n"
+    "varying vec4 vertexColor;\n"
+    "void main(void)\n"
+    "{\n"
+    "    if (texCoord.x>=0.0) gl_FragColor = vertexColor * vec4(1.0, 1.0, 1.0, texture2D(glyphTexture, texCoord).a);\n"
+    "    else gl_FragColor = vertexColor;\n"
+    "}\n"
+};
+#endif
 
 osg::ref_ptr<Font>& Font::getDefaultFont()
 {
@@ -240,14 +301,40 @@ Font::Font(FontImplementation* implementation):
 
     _texenv = new osg::TexEnv;
     _stateset = new osg::StateSet;
+
     _stateset->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
     _stateset->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
     _stateset->setMode(GL_BLEND, osg::StateAttribute::ON);
 
-#if defined(OSG_GL_FIXED_FUNCTION_AVAILABLE)
+#if FIXED_FUNCTION
+
+    OSG_NOTICE<<"Font::Font() Fixed function pipeline"<<std::endl;
+
     _stateset->setTextureMode(0, GL_TEXTURE_2D, osg::StateAttribute::ON);
 #endif
 
+#if SHADERS_GL3
+
+    OSG_NOTICE<<"Font::Font() Setting up GL3 compatible shaders"<<std::endl;
+
+    osg::ref_ptr<osg::Program> program = new osg::Program;
+    program->addShader(new osg::Shader(osg::Shader::VERTEX, gl3_TextVertexShader));
+    program->addShader(new osg::Shader(osg::Shader::FRAGMENT, gl3_TextFragmentShader));
+    _stateset->setAttributeAndModes(program.get());
+    _stateset->addUniform(new osg::Uniform("glyphTexture", 0));
+
+#elif SHADERS_GL2
+
+    OSG_NOTICE<<"Font::Font() Setting up GL2 compatible shaders"<<std::endl;
+
+    osg::ref_ptr<osg::Program> program = new osg::Program;
+    program->addShader(new osg::Shader(osg::Shader::VERTEX, gl2_TextVertexShader));
+    program->addShader(new osg::Shader(osg::Shader::FRAGMENT, gl2_TextFragmentShader));
+    _stateset->setAttributeAndModes(program.get());
+    _stateset->addUniform(new osg::Uniform("glyphTexture", 0));
+
+#endif
+
     char *ptr;
     if( (ptr = getenv("OSG_MAX_TEXTURE_SIZE")) != 0)
     {
diff --git a/src/osgText/Text3D.cpp b/src/osgText/Text3D.cpp
index 17bbe4282..ce94840fb 100644
--- a/src/osgText/Text3D.cpp
+++ b/src/osgText/Text3D.cpp
@@ -491,6 +491,9 @@ void Text3D::drawImplementation(osg::RenderInfo& renderInfo) const
         // ** apply this new modelview matrix
         state.applyModelViewMatrix(modelview);
 
+        // workaround for GL3/GL2
+        if (state.getUseModelViewAndProjectionUniforms()) state.applyModelViewAndProjectionUniformsIfRequired();
+
         // OSG_NOTICE<<"New state.applyModelViewMatrix() "<<modelview<<std::endl;
     }
     else
@@ -516,8 +519,10 @@ void Text3D::drawImplementation(osg::RenderInfo& renderInfo) const
 
         if (!_decorationPrimitives.empty())
         {
-            osg::State::ApplyModeProxy applyMode(state, GL_LIGHTING, false);
+        #if !defined(OSG_GLES1_AVAILABLE) && !defined(OSG_GLES2_AVAILABLE) && !defined(OSG_GL3_AVAILABLE)
+            osg::State::ApplyModeProxy applyLightingMode(state, GL_LIGHTING, false);
             osg::State::ApplyTextureModeProxy applyTextureMode(state, 0, GL_TEXTURE_2D, false);
+        #endif
 
             for(Primitives::const_iterator itr = _decorationPrimitives.begin();
                 itr != _decorationPrimitives.end();
@@ -533,9 +538,11 @@ void Text3D::drawImplementation(osg::RenderInfo& renderInfo) const
         state.Color(_color.r(),_color.g(),_color.b(),_color.a());
 
         #if !defined(OSG_GLES1_AVAILABLE) && !defined(OSG_GLES2_AVAILABLE) && !defined(OSG_GL3_AVAILABLE)
-            renderInfo.getState()->applyMode(GL_NORMALIZE, true);
+        osg::State::ApplyModeProxy applyNormalizeMode(state, GL_NORMALIZE, true);
+        osg::State::ApplyModeProxy applyLightingMode(state, GL_LIGHTING, true);
         #endif
 
+
         const osg::StateSet* frontStateSet = getStateSet();
         const osg::StateSet* wallStateSet = getWallStateSet();
         const osg::StateSet* backStateSet = getBackStateSet();
@@ -574,6 +581,9 @@ void Text3D::drawImplementation(osg::RenderInfo& renderInfo) const
     {
         // restore the previous modelview matrix
         state.applyModelViewMatrix(previous_modelview);
+
+        // workaround for GL3/GL2
+        if (state.getUseModelViewAndProjectionUniforms()) state.applyModelViewAndProjectionUniformsIfRequired();
     }
 }