source: trunk/src/gl/gl_context.cc @ 492

// Copyright (C) 2012-2015 ChaosForge Ltd
// http://chaosforge.org/
//
// This file is part of Nova libraries. 
// For conditions of distribution and use, see copying.txt file in root folder.

#include "nv/gl/gl_context.hh"

#include "nv/gl/gl_enum.hh"
#include "nv/lib/gl.hh"
#include "nv/gl/gl_device.hh"
#include "nv/core/logger.hh"

using namespace nv;

nv::vertex_array nv::gl_context::create_vertex_array( const vertex_array_desc& desc )
{
        vertex_array result = m_vertex_arrays.create();
        gl_vertex_array_info* info = m_vertex_arrays.get( result );

        glGenVertexArrays( 1, &info->glid );
        info->count       = desc.count;
        info->index       = desc.index;
        info->index_owner = desc.index_owner;
        info->index_type  = desc.index_type;

        for ( uint32 i = 0; i < desc.count; ++i )
                info->attr[i] = desc.attr[i];

        glBindVertexArray( info->glid );

        for ( uint32 i = 0; i < info->count; ++i )
        {
                const vertex_buffer_attribute& vba = info->attr[i];
                uint32 location = static_cast<uint32>( vba.location );
                glEnableVertexAttribArray( location );
                const gl_buffer_info* vinfo = static_cast<const gl_buffer_info*>( m_device->get_buffer_info( vba.vbuffer ) );
                if ( vinfo && vinfo->type == VERTEX_BUFFER )
                        glBindBuffer( GL_ARRAY_BUFFER, vinfo->glid );
                else
                {
                        // TODO: report error
                }

                glVertexAttribPointer(
                        location,
                        static_cast<GLint>( vba.components ),
                        nv::datatype_to_gl_enum( vba.dtype ),
                        GL_FALSE,
                        static_cast<GLsizei>( vba.stride ),
                        reinterpret_cast<void*>( vba.offset )
                        );
        }
        glBindBuffer( GL_ARRAY_BUFFER, 0 );

        if ( info->index.is_valid() )
        {
                const gl_buffer_info* iinfo = static_cast<const gl_buffer_info*>( m_device->get_buffer_info( info->index ) );
                if ( iinfo && iinfo->type == INDEX_BUFFER )
                {
                        glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, iinfo->glid );
                }
                else
                {
                        // TODO: report error
                }
        }
        glBindBuffer( GL_ARRAY_BUFFER, 0 );
        glBindVertexArray( 0 );

        if ( info->index.is_valid() )
        {
                glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, 0 );
        }

//      for ( uint32 i = 0; i < info->count; ++i )
//      {
//              glDisableVertexAttribArray( static_cast<uint32>( info->attr[i].location ) );
//      }


        return result;
}

nv::framebuffer nv::gl_context::create_framebuffer( uint32 temp_samples )
{
        unsigned glid   = 0;
        glGenFramebuffers( 1, &glid );
        framebuffer result = m_framebuffers.create();
        gl_framebuffer_info* info = m_framebuffers.get( result );
        info->glid = glid;
        info->depth_rb_glid = 0;
        info->color_attachment_count = 0;
        info->sample_count = temp_samples;
        return result;
}

void nv::gl_context::release( vertex_array va )
{
        gl_vertex_array_info* info = m_vertex_arrays.get( va );
        if ( info )
        {
                for ( uint32 i = 0; i < info->count; ++i )
                {
                        if ( info->attr[i].owner ) 
                                m_device->release( info->attr[i].vbuffer );
                }
                if ( info->index.is_valid() && info->index_owner) m_device->release( info->index );
                glDeleteVertexArrays( 1, &info->glid );
                m_vertex_arrays.destroy( va );
        }
}

void nv::gl_context::release( framebuffer f )
{
        gl_framebuffer_info* info = m_framebuffers.get( f );
        if ( info )
        {
                // TODO: release textures?
                glBindFramebuffer( GL_FRAMEBUFFER, 0 );
                glBindRenderbuffer( GL_RENDERBUFFER, 0 );
                if ( info->depth_rb_glid == 0 )
                        glDeleteRenderbuffers( 1, &info->depth_rb_glid );
                glDeleteFramebuffers( 1, &info->glid );
                m_framebuffers.destroy( f );
        }
}

const framebuffer_info* nv::gl_context::get_framebuffer_info( framebuffer f ) const
{
        return m_framebuffers.get( f );
}

void nv::gl_context::attach( framebuffer f, output_slot slot, texture t )
{
        // TODO: framebuffer variable, so no re-binding?
        // TODO: support 1d, 3d textures, cubemaps or layers?
        // TODO: support GL_READ_FRAMEBUFFER?
        const gl_framebuffer_info* info  = m_framebuffers.get( f );
        const gl_texture_info*     tinfo = static_cast< const gl_texture_info* >( m_device->get_texture_info( t ) );
        if ( info )
        {
                glBindFramebuffer( GL_FRAMEBUFFER, info->glid );
                unsigned gl_type = texture_type_to_enum( tinfo->type );

                if ( tinfo )
                {
                        //              if ( tinfo->size.y == 0 )
                                //                      glFramebufferTexture1D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0+(unsigned)slot, GL_TEXTURE_1D, tinfo->glid, 0 );
                        glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0+unsigned( slot ), gl_type, tinfo->glid, 0 );
                }
                else
                {
                        glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0+unsigned( slot ), gl_type, 0, 0 );
                }

        }
}

void nv::gl_context::attach( framebuffer f, texture depth, int layer /*= -1*/ )
{
        // TODO: framebuffer variable, so no re-binding?
        // TODO: support GL_READ_FRAMEBUFFER?
        const gl_framebuffer_info* info  = m_framebuffers.get( f );
        const gl_texture_info*     tinfo = static_cast< const gl_texture_info* >( m_device->get_texture_info( depth ) );
        if ( info )
        {
                glBindFramebuffer( GL_FRAMEBUFFER, info->glid );
                unsigned gl_type = texture_type_to_enum( tinfo->type );
                unsigned glid = ( tinfo ? tinfo->glid : 0 );
                if ( layer >= 0 )
                {
                        glFramebufferTextureLayer( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, tinfo->glid, 0, layer );
                }
                else
                {
                        glFramebufferTexture2D( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, gl_type, glid, 0 );
                }
        }

}

void nv::gl_context::attach( framebuffer f, ivec2 size )
{
        // TODO: framebuffer variable, so no re-binding?
        // TODO: support GL_READ_FRAMEBUFFER?
        gl_framebuffer_info* info  = m_framebuffers.get( f );
        if ( info )
        {
                glBindFramebuffer( GL_FRAMEBUFFER, info->glid );
                if ( info->depth_rb_glid ) 
                        glDeleteRenderbuffers( 1, &(info->depth_rb_glid) );
                glGenRenderbuffers( 1, &(info->depth_rb_glid) );
                glBindRenderbuffer( GL_RENDERBUFFER, info->depth_rb_glid );
                if ( info->sample_count > 1 )
                        glRenderbufferStorageMultisample( GL_RENDERBUFFER, info->sample_count, GL_DEPTH_COMPONENT16, size.x, size.y );
                else
                        glRenderbufferStorage( GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, size.x, size.y );
                glFramebufferRenderbuffer( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, info->depth_rb_glid );
                glBindRenderbuffer( GL_RENDERBUFFER, 0 );
        }

}

void nv::gl_context::blit( framebuffer f, clear_state::buffers_type mask, ivec2 src1, ivec2 src2, ivec2 dst1, ivec2 dst2 )
{
        gl_framebuffer_info* info  = m_framebuffers.get( f );
        if ( info )
        {
                glBindFramebuffer( GL_FRAMEBUFFER, info->glid );
                unsigned filter = mask == clear_state::COLOR_BUFFER ? GL_LINEAR : GL_NEAREST;
                glBlitFramebuffer( src1.x, src1.y, src2.x, src2.y, dst1.x, dst1.y, dst2.x, dst2.y, clear_state_buffers_to_mask( mask ), filter );
        }
}


void nv::gl_context::blit( framebuffer from, framebuffer to, clear_state::buffers_type mask, ivec2 src1, ivec2 src2, ivec2 dst1, ivec2 dst2 )
{
        gl_framebuffer_info* finfo = m_framebuffers.get( from );
        gl_framebuffer_info* tinfo = m_framebuffers.get( to );
        if ( finfo )
        {
                glBindFramebuffer( GL_READ_FRAMEBUFFER, finfo->glid );
                glBindFramebuffer( GL_DRAW_FRAMEBUFFER, tinfo ? tinfo->glid : 0 );
                unsigned filter = mask == clear_state::COLOR_BUFFER ? GL_LINEAR : GL_NEAREST;
                int remove_below;
                filter = GL_NEAREST;
                glBlitFramebuffer( src1.x, src1.y, src2.x, src2.y, dst1.x, dst1.y, dst2.x, dst2.y, clear_state_buffers_to_mask( mask ), filter );
                glBindFramebuffer( GL_READ_FRAMEBUFFER, 0 );
                if ( tinfo ) glBindFramebuffer( GL_DRAW_FRAMEBUFFER, 0 );
        }
}

bool nv::gl_context::check( framebuffer_slot ft )
{
        glDrawBuffer( 0 );
        glReadBuffer( 0 );

        unsigned result = glCheckFramebufferStatus( framebuffer_slot_to_enum(ft) );
        if ( result == GL_FRAMEBUFFER_COMPLETE ) return true;
        switch ( result )
        {
        case GL_FRAMEBUFFER_UNDEFINED                     : NV_LOG_ERROR( "gl_context::check : Framebuffer undefined!" ); break;
        case GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE        : NV_LOG_ERROR( "gl_context::check : Incomplete multisample!" ); break;
        case GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS      : NV_LOG_ERROR( "gl_context::check : Incomplete layer targets!" ); break;
        case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT         : NV_LOG_ERROR( "gl_context::check : Framebuffer incomplete attachment!" ); break;
        case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT : NV_LOG_ERROR( "gl_context::check : Framebuffer missing attachment!" ); break;
//              case GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS         : NV_LOG_ERROR( "gl_context::check : Framebuffer incomplete dimensions!" ); break;
//              case GL_FRAMEBUFFER_INCOMPLETE_FORMATS            : NV_LOG_ERROR( "gl_context::check : Framebuffer incomplete formats!" ); break;
        case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER        : NV_LOG_ERROR( "gl_context::check : Framebuffer incomplete draw buffer!" ); break;
        case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER        : NV_LOG_ERROR( "gl_context::check : Framebuffer incomplete read buffer!" ); break;
        case GL_FRAMEBUFFER_UNSUPPORTED                   : NV_LOG_ERROR( "gl_context::check : Framebuffer format combination unsupported!" ); break;
        default: NV_LOG_ERROR( "gl_context::check : Unknown Framebuffer error! (", result, ")" ); break;
        }
        glDrawBuffer( GL_BACK );
        glReadBuffer( GL_BACK );
        return false;
}

void nv::gl_context::bind( framebuffer f, framebuffer_slot ft /*= FRAMEBUFFER_BOTH */ )
{
        const gl_framebuffer_info* info = m_framebuffers.get( f );
        if ( info )
        {
                glBindFramebuffer( framebuffer_slot_to_enum(ft), info->glid );
        }
        else
        {
                glBindFramebuffer( framebuffer_slot_to_enum(ft), 0 );
        }
}

void nv::gl_context::bind( buffer b, texture t )
{
        const gl_buffer_info*  binfo = static_cast< const gl_buffer_info* >( m_device->get_buffer_info( b ) );
        const gl_texture_info* tinfo = static_cast< const gl_texture_info* >( m_device->get_texture_info( t ) );
        NV_ASSERT( binfo && tinfo, "Bad buffer or texture passed to create_texture" );
        if ( binfo && tinfo )
        {
                NV_ASSERT_ALWAYS( binfo->type == TEXTURE_BUFFER && tinfo->type == TEXTURE_1D_BUFFER, "bad texture or buffer type!" );
                bind( t, TEXTURE_0 );
                glTexBuffer( GL_TEXTURE_BUFFER, image_format_to_internal_enum( tinfo->format.format ), binfo->glid );
        }
}

void nv::gl_context::bind( buffer b, uint32 index, size_t offset /*= 0*/, size_t size /*= 0 */ )
{
        const gl_buffer_info* info = static_cast< const gl_buffer_info* >( m_device->get_buffer_info( b ) );
        if ( info )
        {
                if ( size == 0 )
                        glBindBufferBase( buffer_type_to_enum( info->type ), index, info->glid );
                else
                        glBindBufferRange( buffer_type_to_enum( info->type ), index, info->glid, static_cast<GLintptr>( offset ), static_cast<GLsizeiptr>( size ) );
        }
}

void gl_context::bind( texture t, texture_slot slot )
{
        if ( m_bound_textures[ slot ] != t )
        {
                const gl_texture_info* info = static_cast< const gl_texture_info* >( m_device->get_texture_info( t ) );
                if ( info )
                {
                        set_active_texture( slot );
                        glBindTexture( texture_type_to_enum( info->type ), info->glid );
                }
        }
}

void nv::gl_context::bind( program p )
{
        gl_device* gdevice    = static_cast<gl_device*>( m_device );
        gl_program_info* info = gdevice->m_programs.get( p );
        if ( info )
        {
                glUseProgram( info->glid );
                gdevice->update_uniforms( info );
        }
}

// void nv::gl_context::bind( buffer b )
// {
//      const gl_buffer_info* info = static_cast< const gl_buffer_info* >( m_device->get_buffer_info( b ) );
//      if ( info )
//      {
//              glBindBuffer( buffer_type_to_enum( info->type ), info->glid );
//      }
// }

void nv::gl_context::bind( vertex_array va )
{
        gl_vertex_array_info* info = m_vertex_arrays.get( va );
        if ( info )
        {
                glBindVertexArray( info->glid );
        }
}

void nv::gl_context::unbind( program )
{
        glUseProgram( 0 );
}

void nv::gl_context::set_active_texture( texture_slot slot )
{
        if ( slot != m_active_slot )
                glActiveTexture( GL_TEXTURE0 + static_cast<GLenum>( slot ) );
}

// void nv::gl_context::unbind( buffer b )
// {
//      const gl_buffer_info* info = static_cast< const gl_buffer_info* >( m_device->get_buffer_info( b ) );
//      if ( info )
//      {
//              glBindBuffer( buffer_type_to_enum( info->type ), 0 );
//      }
// }

void nv::gl_context::unbind( vertex_array va )
{
        const vertex_array_info* info = m_vertex_arrays.get( va );
        if ( info )
        {
                glBindVertexArray( 0 );
        }
}

void nv::gl_context::unbind( framebuffer f )
{
        // this way we are sure that the extension is loaded
        const gl_framebuffer_info* info = m_framebuffers.get( f );
        if ( info )
        {
                glBindFramebuffer( GL_FRAMEBUFFER, 0 );
        }
        glDrawBuffer( GL_BACK );
        glReadBuffer( GL_BACK );
}

void nv::gl_context::update( texture t, const void* data )
{
        const gl_texture_info* info = static_cast< const gl_texture_info* >( m_device->get_texture_info( t ) );
        NV_ASSERT_ALWAYS( info->type != TEXTURE_1D_BUFFER, "Buffer texture passed to update!" );
        NV_ASSERT_ALWAYS( info->type != TEXTURE_2D_MULTISAMPLE, "Multisample texture passed to update!" );
        if ( info )
        {
                image_format format  = info->format;
                ivec3        size    = info->size;
                unsigned     gl_type = texture_type_to_enum( info->type );

                if ( m_bound_textures[ m_active_slot ] != t )
                        glBindTexture( gl_type, info->glid );
                int this_should_be_subTexImage;
                if ( info->type == TEXTURE_3D || info->type == TEXTURE_2D_ARRAY )
                        glTexImage3D( gl_type, 0, static_cast<GLint>( nv::image_format_to_internal_enum( format.format ) ), size.x, size.y, size.z, 0, nv::image_format_to_enum( format.format ), nv::datatype_to_gl_enum( format.type ), data );
                else
                        glTexImage2D( gl_type, 0, static_cast<GLint>( nv::image_format_to_internal_enum(format.format) ), size.x, size.y, 0, nv::image_format_to_enum(format.format), nv::datatype_to_gl_enum(format.type), data );
        }
}

// void nv::gl_context::update( buffer b, uint32 index, const void* data, size_t offset, size_t size )
// {
//      const gl_buffer_info* info = static_cast<const gl_buffer_info*>( m_device->get_buffer_info( b ) );
//      if ( info )
//      {
//              GLenum glenum = buffer_type_to_enum( info->type );
//              if ( size == 0 )
//                      glBindBufferBase( glenum, index, info->glid );
//              else
//                      glBindBufferRange( glenum, index, info->glid, offset, size );
//              glBufferSubData( glenum, GLintptr( offset ), GLsizeiptr( size ), data );
//      }
// }

void gl_context::update( buffer b, const void* data, nv::size_t offset, nv::size_t size )
{
        const gl_buffer_info* info = static_cast< const gl_buffer_info* >( m_device->get_buffer_info( b ) );
        if ( info )
        {
                GLenum glenum = buffer_type_to_enum( info->type );
                glBindBuffer( glenum, info->glid );
                glBufferSubData( glenum, GLintptr( offset ), GLsizeiptr( size ), data );
        }
}

void gl_context::clear( const clear_state& cs )
{
        // apply_framebuffer
        
        apply_scissor_test( cs.scissor_test );
        apply_color_mask( cs.color_mask );
        apply_depth_mask( cs.depth_mask );
        // stencil_mask_separate

        if ( m_clear_color != cs.color )
        {
                glClearColor( cs.color.r, cs.color.g, cs.color.b, cs.color.a );
                m_clear_color = cs.color;
        }

        if ( m_clear_depth != cs.depth )
        {
                glClearDepth( cs.depth );
                m_clear_depth = cs.depth;
        }

        if ( m_clear_stencil != cs.stencil )
        {
                glClearStencil( cs.stencil );
                m_clear_stencil = cs.stencil;
        }
        
        glClear( clear_state_buffers_to_mask( cs.buffers ) );
}

const ivec4& gl_context::get_viewport()
{
        return m_viewport;
}

void gl_context::set_viewport( const ivec4& viewport )
{
        NV_ASSERT_ALWAYS( viewport.z > 0 && viewport.w > 0, "viewport dimensions must be greater than zero!" );
        m_viewport = viewport;
        glViewport( viewport.x, viewport.y, viewport.z, viewport.w );
}

void gl_context::enable( unsigned int what, bool value )
{
        if ( value )
        {
                glEnable( what );
        }
        else
        {
                glDisable( what );
        }
}

void gl_context::apply_stencil_test( const stencil_test& stencil )
{
        if ( m_render_state.stencil_test.enabled != stencil.enabled )
        {
                enable( GL_STENCIL_TEST, stencil.enabled );
                m_render_state.stencil_test.enabled = stencil.enabled;
        }
        
        if ( stencil.enabled )
        {
                apply_stencil_face( GL_FRONT, m_render_state.stencil_test.front_face, stencil.front_face );
                apply_stencil_face( GL_BACK,  m_render_state.stencil_test.back_face,  stencil.back_face );
        }
}

void gl_context::apply_stencil_face( unsigned face, stencil_test_face& stencil, const stencil_test_face& new_stencil )
{
        if (( stencil.op_fail       != new_stencil.op_fail       ) ||
                ( stencil.op_depth_fail != new_stencil.op_depth_fail ) ||
                ( stencil.op_depth_pass != new_stencil.op_depth_pass ) )
        {
                glStencilOpSeparate( face,
                        stencil_operation_to_enum( new_stencil.op_fail ),
                        stencil_operation_to_enum( new_stencil.op_depth_fail ),
                        stencil_operation_to_enum( new_stencil.op_depth_pass )
                );

                stencil.op_fail       = new_stencil.op_fail;
                stencil.op_depth_fail = new_stencil.op_depth_fail;
                stencil.op_depth_pass = new_stencil.op_depth_pass;
        }

        if (( stencil.function  != new_stencil.function ) ||
                ( stencil.ref_value != new_stencil.ref_value ) ||
                ( stencil.mask      != new_stencil.mask ))
        {
                glStencilFuncSeparate( face,
                        stencil_function_to_enum( new_stencil.function ),
                        new_stencil.ref_value,
                        new_stencil.mask
                );

                stencil.function  = new_stencil.function;
                stencil.ref_value = new_stencil.ref_value;
                stencil.mask      = new_stencil.mask;
        }
}

void gl_context::apply_scissor_test( const scissor_test& scissor )
{
        if ( m_render_state.scissor_test.enabled != scissor.enabled )
        {
                enable( GL_SCISSOR_TEST, scissor.enabled );
                m_render_state.scissor_test.enabled = scissor.enabled;
        }


        if ( scissor.enabled )
        {
                NV_ASSERT_ALWAYS( scissor.dim.x > 0 && scissor.dim.y > 0, "scissor_test.rect dimension equal to zero!" );

                if ( m_render_state.scissor_test.dim != scissor.dim || m_render_state.scissor_test.pos != scissor.pos )
                {
                        glScissor( 
                                scissor.pos.x, scissor.pos.y, 
                                scissor.dim.x, scissor.dim.y
                        );
                        m_render_state.scissor_test.dim = scissor.dim;
                        m_render_state.scissor_test.pos = scissor.pos;
                }
        }
}

void gl_context::apply_depth_test( const depth_test& depth )
{
        if ( m_render_state.depth_test.enabled != depth.enabled )
        {
                enable( GL_DEPTH_TEST, depth.enabled );
                m_render_state.depth_test.enabled = depth.enabled;
        }

        if ( depth.enabled )
        {
                if ( m_render_state.depth_test.function != depth.function )
                {
                        glDepthFunc( depth_state_function_to_enum( depth.function ) );
                        m_render_state.depth_test.function = depth.function;
                }
        }
}

void gl_context::apply_depth_mask( bool mask )
{
        if ( m_render_state.depth_mask != mask )
        {
                glDepthMask( mask );
                m_render_state.depth_mask = mask;
        }
}

void gl_context::apply_multisample( bool multisample )
{
        if ( m_render_state.multisample != multisample )
        {
                glDepthMask( multisample );
                m_render_state.multisample = multisample;
        }
}

void gl_context::apply_polygon_mode( const polygon_mode& mode )
{
        if ( m_render_state.polygon_mode.fill != mode.fill )
        {
                glPolygonMode( GL_FRONT_AND_BACK, polygon_mode_fill_to_enum( mode.fill ) );
                m_render_state.polygon_mode.fill = mode.fill;
        }
}


void gl_context::apply_depth_range( const depth_range& range )
{
        NV_ASSERT_ALWAYS( range.near >= 0.0 && range.near <= 1.0, "render_state.depth_range.near must be between zero and one!" );
        NV_ASSERT_ALWAYS( range.far  >= 0.0 && range.far  <= 1.0, "render_state.depth_range.far must be between zero and one!" );

        if ((m_render_state.depth_range.far  != range.far) ||
                (m_render_state.depth_range.near != range.near))
        {
                glDepthRange( range.near, range.far );

                m_render_state.depth_range.far  = range.far;
                m_render_state.depth_range.near = range.near;
        }
}

void gl_context::apply_color_mask( const color_mask& mask )
{
        if ( m_render_state.color_mask != mask )
        {
                glColorMask( mask.red, mask.green, mask.blue, mask.alpha );
                m_render_state.color_mask = mask;
        }
}

void gl_context::apply_blending( const blending& blend )
{
        if ( m_render_state.blending.enabled != blend.enabled )
        {
                enable( GL_BLEND, blend.enabled );
                m_render_state.blending.enabled = blend.enabled;
        }

        if ( blend.enabled )
        {
                if ((m_render_state.blending.src_rgb_factor   != blend.src_rgb_factor ) ||
                        (m_render_state.blending.dst_rgb_factor   != blend.dst_rgb_factor ) ||
                        (m_render_state.blending.src_alpha_factor != blend.src_alpha_factor ) ||
                        (m_render_state.blending.dst_alpha_factor != blend.dst_alpha_factor ))
                {
                        glBlendFuncSeparate(
                                blending_factor_to_enum( blend.src_rgb_factor ),
                                blending_factor_to_enum( blend.dst_rgb_factor ),
                                blending_factor_to_enum( blend.src_alpha_factor ),
                                blending_factor_to_enum( blend.dst_alpha_factor )
                        );

                        m_render_state.blending.src_rgb_factor   = blend.src_rgb_factor;
                        m_render_state.blending.dst_rgb_factor   = blend.dst_rgb_factor;
                        m_render_state.blending.src_alpha_factor = blend.src_alpha_factor;
                        m_render_state.blending.dst_alpha_factor = blend.dst_alpha_factor; 
                }

                if ((m_render_state.blending.rgb_equation   != blend.rgb_equation ) ||
                        (m_render_state.blending.alpha_equation != blend.alpha_equation ))
                {
                        glBlendEquationSeparate(
                                blending_equation_to_enum( blend.rgb_equation ),
                                blending_equation_to_enum( blend.alpha_equation )
                        );

                        m_render_state.blending.rgb_equation   = blend.rgb_equation;
                        m_render_state.blending.alpha_equation = blend.alpha_equation;
                }

                if (( m_render_state.blending.color != blend.color ))
                {
                        glBlendColor( blend.color.r, blend.color.g, blend.color.b, blend.color.a );
                        m_render_state.blending.color = blend.color;
                }
        }
}


void gl_context::apply_culling( const culling& cull )
{
        if ( m_render_state.culling.enabled != cull.enabled )
        {
                enable( GL_CULL_FACE, cull.enabled );
                m_render_state.culling.enabled = cull.enabled;
        }

        if ( cull.enabled )
        {
                if ( m_render_state.culling.face != cull.face )
                {
                        glCullFace( culling_face_type_to_enum( cull.face ) );
                        m_render_state.culling.face = cull.face;
                }
        }

        if ( m_render_state.culling.order != cull.order )
        {
                glFrontFace( culling_order_type_to_enum( cull.order ) );
                m_render_state.culling.order = cull.order;
        }
}


void gl_context::force_apply_render_state( const render_state& state )
{
        enable( GL_CULL_FACE, state.culling.enabled );
        glCullFace( culling_face_type_to_enum( state.culling.face ) );
        glFrontFace( culling_order_type_to_enum( state.culling.order ) );

        enable( GL_SCISSOR_TEST, state.scissor_test.enabled );
        glScissor( 
                state.scissor_test.pos.x, state.scissor_test.pos.y, 
                state.scissor_test.dim.x, state.scissor_test.dim.y 
        );

        enable( GL_STENCIL_TEST, state.stencil_test.enabled );
        force_apply_stencil_face( GL_FRONT, state.stencil_test.front_face );
        force_apply_stencil_face( GL_BACK,  state.stencil_test.back_face  );

        enable( GL_DEPTH_TEST, state.depth_test.enabled );
        glDepthFunc( depth_state_function_to_enum( state.depth_test.function ) );
        glDepthRange( state.depth_range.near, state.depth_range.far );

        enable( GL_BLEND, state.blending.enabled );
        glBlendFuncSeparate(
                blending_factor_to_enum( state.blending.src_rgb_factor ),
                blending_factor_to_enum( state.blending.dst_rgb_factor ),
                blending_factor_to_enum( state.blending.src_alpha_factor ),
                blending_factor_to_enum( state.blending.dst_alpha_factor )
        );
        glBlendEquationSeparate(
                blending_equation_to_enum( state.blending.rgb_equation ),
                blending_equation_to_enum( state.blending.alpha_equation )
        );
        glBlendColor( 
                state.blending.color.r, state.blending.color.g, 
                state.blending.color.b, state.blending.color.a 
        );

        glDepthMask( state.depth_mask );
        glColorMask( 
                state.color_mask.red, state.color_mask.green, 
                state.color_mask.blue, state.color_mask.alpha 
        );
        glPolygonMode( GL_FRONT_AND_BACK, polygon_mode_fill_to_enum( state.polygon_mode.fill ) );
}

void gl_context::force_apply_stencil_face( unsigned face, const stencil_test_face& stencil )
{
        glStencilOpSeparate( face,
                stencil_operation_to_enum( stencil.op_fail ),
                stencil_operation_to_enum( stencil.op_depth_fail ),
                stencil_operation_to_enum( stencil.op_depth_pass )
        );

        glStencilFuncSeparate( face,
                stencil_function_to_enum( stencil.function ),
                stencil.ref_value,
                stencil.mask
        );
}


void gl_context::apply_render_state( const render_state& state )
{
        // apply_primitive_restart
        apply_culling( state.culling );
        // apply_program_point_size
        // apply_rasterization_mode
        apply_scissor_test( state.scissor_test );
        apply_stencil_test( state.stencil_test );
        apply_depth_test( state.depth_test );
        apply_depth_range( state.depth_range );
        apply_blending( state.blending );
        apply_color_mask( state.color_mask );
        apply_depth_mask( state.depth_mask );
        apply_multisample( state.multisample );
        apply_polygon_mode( state.polygon_mode );
}


gl_context::gl_context( device* a_device, void* a_handle )
        : context( a_device ), m_handle( a_handle )
{
        // TODO: configurable:
//      load_gl_extensions( GL_EXT_FRAMEBUFFER_BLIT | GL_EXT_FRAMEBUFFER_OBJECT | GL_EXT_TEXTURE_ARRAY );
        m_active_slot = texture_slot( -1 );
        force_apply_render_state( m_render_state );
}


nv::gl_context::~gl_context()
{
        while ( m_framebuffers.size() > 0 )
                release( m_framebuffers.get_handle(0) );
        while ( m_vertex_arrays.size() > 0 )
                release( m_vertex_arrays.get_handle(0) );
}

void nv::gl_context::apply_engine_uniforms( program p, const scene_state& s )
{
        gl_program_info* info = static_cast<gl_device*>( m_device )->m_programs.get( p );
        if ( info )
        {
                for ( auto& u : *info->m_engine_uniforms )
                {
                        u->set( this, &s );
                }
        }
}

void nv::gl_context::set_draw_buffers( uint32 count, const output_slot* slots )
{
        if ( count == 0 ) return;
        if ( count == 1 )
        {
                set_draw_buffer( slots[0] );
                return;
        }
        unsigned int buffers[8];
        count = nv::min<uint32>( count, 8 );
        for ( uint32 i = 0; i < count; ++i )
        {
                buffers[i] = output_slot_to_enum( slots[i] );
                if ( slots[i] > OUTPUT_7 ) buffers[i] = 0;
        }
        glDrawBuffers( GLsizei( count ), buffers );
}

void nv::gl_context::set_draw_buffer( output_slot slot )
{
        glDrawBuffer( output_slot_to_enum(slot) );
}

void nv::gl_context::set_read_buffer( output_slot slot )
{
        glReadBuffer( output_slot_to_enum(slot) );
}

void gl_context::draw( primitive prim, const render_state& rs, program p, vertex_array va, nv::size_t count, nv::size_t first )
{
        apply_render_state( rs );
        const vertex_array_info* info = m_vertex_arrays.get( va );
        if ( count > 0 && info )
        {
                bind( p );
                bind( va );
                if ( info->index.is_valid() )
                {
                        glDrawElements( primitive_to_enum(prim), static_cast<GLsizei>( count ), datatype_to_gl_enum( info->index_type ), reinterpret_cast< const void* >( get_datatype_info( info->index_type ).size * first ) );
                }
                else
                {
                        glDrawArrays( primitive_to_enum(prim), static_cast<GLint>( first ), static_cast<GLsizei>( count ) );
                }
                unbind( va );
                //unbind( p );
        }
}