make it possible to easily have variants of glsl programs

Now it's possible to add a preamble to the compiled program, so there can
be just one program with #ifdef's inside and the small variants can be
selected using #define in the preamble instead of having several almost
identical programs.

Change-Id: I6c5112313b91b6269ebdecdfc896e0f96209ea2b

include/vcl/opengl/OpenGLContext.hxx

@@ -161,8 +161,6 @@ struct GLWindow
     ~GLWindow();
 };
 
-typedef std::pair<OUString, OUString> ProgramKey;
-
 class VCLOPENGL_DLLPUBLIC OpenGLContext
 {
 public:
@@ -203,8 +201,8 @@ public:
     void               ReleaseFramebuffers();
 
     // retrieve a program from the cache or compile/link it
-    OpenGLProgram*      GetProgram( const OUString& rVertexShader, const OUString& rFragmentShader );
-    OpenGLProgram*      UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader );
+    OpenGLProgram*      GetProgram( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble = "" );
+    OpenGLProgram*      UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble = "" );
 
     bool isCurrent();
     static void clearCurrent();
@@ -266,6 +264,14 @@ private:
     OpenGLFramebuffer* mpFirstFramebuffer;
     OpenGLFramebuffer* mpLastFramebuffer;
 
+    struct ProgramKey
+    {
+        ProgramKey( const OUString& vertexShader, const OUString& fragmentShader, const OString& preamble );
+        bool operator< ( const ProgramKey& other ) const;
+        OUString vertexShader;
+        OUString fragmentShader;
+        OString preamble;
+    };
     boost::ptr_map<ProgramKey, OpenGLProgram> maPrograms;
     OpenGLProgram* mpCurrentProgram;
 #ifdef DBG_UTIL

include/vcl/opengl/OpenGLHelper.hxx

@@ -25,7 +25,7 @@
 class VCLOPENGL_DLLPUBLIC OpenGLHelper
 {
 public:
-    static GLint LoadShaders(const OUString& rVertexShaderName, const OUString& rFragmentShaderName);
+    static GLint LoadShaders(const OUString& rVertexShaderName, const OUString& rFragmentShaderName, const OString& preamble = "" );
 
     /**
      * The caller is responsible for allocate the memory for the RGBA buffer, before call

vcl/inc/opengl/program.hxx

@@ -43,7 +43,7 @@ public:
     OpenGLProgram();
     ~OpenGLProgram();
 
-    bool Load( const OUString& rVertexShader, const OUString& rFragmentShader );
+    bool Load( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble = "" );
     bool Use();
     bool Clean();
 

vcl/inc/openglgdiimpl.hxx

@@ -73,7 +73,7 @@ protected:
     bool CheckOffscreenTexture();
 
 public:
-    bool UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader );
+    bool UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble = "" );
     bool UseSolid( SalColor nColor, sal_uInt8 nTransparency );
     bool UseSolid( SalColor nColor, double fTransparency );
     bool UseSolid( SalColor nColor );

vcl/opengl/gdiimpl.cxx

@@ -373,11 +373,11 @@ bool OpenGLSalGraphicsImpl::CheckOffscreenTexture()
     return true;
 }
 
-bool OpenGLSalGraphicsImpl::UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader )
+bool OpenGLSalGraphicsImpl::UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble )
 {
     if( mpProgram != NULL )
         mpProgram->Clean();
-    mpProgram = mpContext->UseProgram( rVertexShader, rFragmentShader );
+    mpProgram = mpContext->UseProgram( rVertexShader, rFragmentShader, preamble );
 #ifdef DBG_UTIL
     mProgramIsSolidColor = false; // UseSolid() will set to true if needed
 #endif

vcl/opengl/program.cxx

@@ -31,9 +31,9 @@ OpenGLProgram::~OpenGLProgram()
         glDeleteProgram( mnId );
 }
 
-bool OpenGLProgram::Load( const OUString& rVertexShader, const OUString& rFragmentShader )
+bool OpenGLProgram::Load( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble )
 {
-    mnId = OpenGLHelper::LoadShaders( rVertexShader, rFragmentShader );
+    mnId = OpenGLHelper::LoadShaders( rVertexShader, rFragmentShader, preamble );
     return ( mnId != 0 );
 }
 

vcl/source/opengl/OpenGLContext.cxx

@@ -1582,9 +1582,9 @@ void OpenGLContext::ReleaseFramebuffers()
     }
 }
 
-OpenGLProgram* OpenGLContext::GetProgram( const OUString& rVertexShader, const OUString& rFragmentShader )
+OpenGLProgram* OpenGLContext::GetProgram( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble )
 {
-    ProgramKey aKey( rVertexShader, rFragmentShader );
+    ProgramKey aKey( rVertexShader, rFragmentShader, preamble );
 
     boost::ptr_map<ProgramKey, OpenGLProgram>::iterator
         it = maPrograms.find( aKey );
@@ -1592,7 +1592,7 @@ OpenGLProgram* OpenGLContext::GetProgram( const OUString& rVertexShader, const O
         return it->second;
 
     OpenGLProgram* pProgram = new OpenGLProgram;
-    if( !pProgram->Load( rVertexShader, rFragmentShader ) )
+    if( !pProgram->Load( rVertexShader, rFragmentShader, preamble ) )
     {
         delete pProgram;
         return NULL;
@@ -1602,9 +1602,9 @@ OpenGLProgram* OpenGLContext::GetProgram( const OUString& rVertexShader, const O
     return pProgram;
 }
 
-OpenGLProgram* OpenGLContext::UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader )
+OpenGLProgram* OpenGLContext::UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble )
 {
-    OpenGLProgram* pProgram = GetProgram( rVertexShader, rFragmentShader );
+    OpenGLProgram* pProgram = GetProgram( rVertexShader, rFragmentShader, preamble );
 
     if( pProgram == mpCurrentProgram )
         return pProgram;
@@ -1615,4 +1615,20 @@ OpenGLProgram* OpenGLContext::UseProgram( const OUString& rVertexShader, const O
     return mpCurrentProgram;
 }
 
+inline
+OpenGLContext::ProgramKey::ProgramKey( const OUString& v, const OUString& f, const OString& p )
+: vertexShader( v ), fragmentShader( f ), preamble( p )
+{
+}
+
+inline
+bool OpenGLContext::ProgramKey::operator< ( const ProgramKey& other ) const
+{
+    if( vertexShader != other.vertexShader )
+        return vertexShader < other.vertexShader;
+    if( fragmentShader != other.fragmentShader )
+        return fragmentShader < other.fragmentShader;
+    return preamble < other.preamble;
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

vcl/source/opengl/OpenGLHelper.cxx

@@ -97,7 +97,7 @@ namespace {
     }
 }
 
-GLint OpenGLHelper::LoadShaders(const OUString& rVertexShaderName,const OUString& rFragmentShaderName)
+GLint OpenGLHelper::LoadShaders(const OUString& rVertexShaderName,const OUString& rFragmentShaderName, const OString& preamble)
 {
     // Create the shaders
     GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
@@ -107,6 +107,8 @@ GLint OpenGLHelper::LoadShaders(const OUString& rVertexShaderName,const OUString
 
     // Compile Vertex Shader
     OString aVertexShaderSource = loadShader(rVertexShaderName);
+    if( !preamble.isEmpty())
+        aVertexShaderSource = preamble + "\n" + aVertexShaderSource;
     char const * VertexSourcePointer = aVertexShaderSource.getStr();
     glShaderSource(VertexShaderID, 1, &VertexSourcePointer , NULL);
     glCompileShader(VertexShaderID);
@@ -119,6 +121,8 @@ GLint OpenGLHelper::LoadShaders(const OUString& rVertexShaderName,const OUString
 
     // Compile Fragment Shader
     OString aFragmentShaderSource = loadShader(rFragmentShaderName);
+    if( !preamble.isEmpty())
+        aFragmentShaderSource = preamble + "\n" + aFragmentShaderSource;
     char const * FragmentSourcePointer = aFragmentShaderSource.getStr();
     glShaderSource(FragmentShaderID, 1, &FragmentSourcePointer , NULL);
     glCompileShader(FragmentShaderID);