added support for vertex array divisor

include/ACGL/OpenGL/Objects/ArrayBuffer.hh

@@ -78,6 +78,7 @@ public:
         GLint       size;       // #elements per attribute, size in bytes would be: size*sizeof(type)
         GLuint      offset;     // offset in bytes into the array
         GLboolean   normalized; // int types can get normalzed to 0..1 / -1..1 by GL, useful e.g. for colors
+        GLuint      divisor;    // vertex divisor for instancing, supported since OpenGL 3.3
     };
 
     // ===================================================================================================== \/
@@ -109,7 +110,7 @@ public:
     // ==================================================================================================== \/
 public:
 
-    //! elements is the number of vertices (unless this AB should get interpreted in a strange way):
+    //! elements is the number of vertices or instances (if the divisor is != 0):
     inline       GLsizei       getElements   (void) const { return (GLsizei) (mStride==0?0:(mSize/mStride)); }
 
     //! size in bytes of all attributes that make up one element (vertex):
@@ -126,16 +127,16 @@ public:
     // ==================================================================================================== \/
 public:
     //! Adds the attribute at the end of the existing attributes, stride gets computed automatically
-    void defineAttribute(            const std::string& _name, GLenum _type, GLint _size, GLboolean _normalized = GL_FALSE);
+    void defineAttribute(            const std::string& _name, GLenum _type, GLint _size, GLboolean _normalized = GL_FALSE, GLuint _divisor = 0);
 
     //! Adds the attribute at the end of the existing attributes, stride gets computed automatically
     //! + extra padding in bytes at the end
-    void defineAttributeWithPadding( const std::string& _name, GLenum _type, GLint _size, GLuint _padding, GLboolean _normalized = GL_FALSE);
+    void defineAttributeWithPadding( const std::string& _name, GLenum _type, GLint _size, GLuint _padding, GLboolean _normalized = GL_FALSE, GLuint _divisor = 0);
 
     //! Adds an attribute defined by an offset: this way an attribute can get added at arbitrary
     //! locations in the stride. If it's added at the end, the stride gets resized. This way attributes can even
     //! overlap, hope you know what you're doing...
-    void defineAttributeWithOffset(  const std::string& _name, GLenum _type, GLint _size, GLuint _offset, GLboolean _normalized = GL_FALSE);
+    void defineAttributeWithOffset(  const std::string& _name, GLenum _type, GLint _size, GLuint _offset, GLboolean _normalized = GL_FALSE, GLuint _divisor = 0);
 
     //! Takes care of a valid stride size and adds the attribute
     void defineAttribute( const Attribute &_attribute );

src/ACGL/OpenGL/Objects/ArrayBuffer.cc

@@ -12,10 +12,11 @@ void ArrayBuffer::defineAttribute(
     const std::string& _name,
     GLenum _type,
     GLint  _size,
-    GLboolean _normalized)
+    GLboolean _normalized,
+    GLuint _divisor )
 {
     GLuint offset = mStride;
-    Attribute attribute = { _name, _type, _size, offset, _normalized };
+    Attribute attribute = { _name, _type, _size, offset, _normalized, _divisor };
     defineAttribute(attribute);
 }
 
@@ -24,10 +25,11 @@ void ArrayBuffer::defineAttributeWithPadding(
     GLenum _type,
     GLint  _size,
     GLuint _padding,
-    GLboolean _normalized)
+    GLboolean _normalized,
+    GLuint _divisor )
 {
     GLuint offset = mStride;
-    Attribute attribute = { _name, _type, _size, offset, _normalized };
+    Attribute attribute = { _name, _type, _size, offset, _normalized, _divisor };
     defineAttribute(attribute);
     // defineAttribute will shift the mStride to the end of this attribute, so we only have to
     // add the explicit padding:
@@ -39,9 +41,10 @@ void ArrayBuffer::defineAttributeWithOffset(
     GLenum _type,
     GLint  _size,
     GLuint _offset,
-    GLboolean _normalized)
+    GLboolean _normalized,
+    GLuint _divisor )
 {
-    Attribute attribute = { _name, _type, _size, _offset, _normalized };
+    Attribute attribute = { _name, _type, _size, _offset, _normalized, _divisor };
     defineAttribute(attribute);
 }
 

src/ACGL/OpenGL/Objects/VertexArrayObject.cc

@@ -209,6 +209,9 @@ void VertexArrayObject::setAttributePointer( GLuint _index )
                           mAttributes[_index].arrayBuffer->getStride(),
                           reinterpret_cast<GLvoid*>(arrayBufferAttribute.offset)
                           );
+    #if (ACGL_OPENGL_VERSION >= 33)
+        glVertexAttribDivisor( _index, arrayBufferAttribute.divisor );
+    #endif
     glEnableVertexAttribArray(_index);
 }