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Read the pixels of asynchronous screenshots over several iterations.
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@j-jorge
j-jorge committed Feb 16, 2017
1 parent 5427324 commit f45d857
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Showing 2 changed files with 172 additions and 31 deletions.
186 changes: 158 additions & 28 deletions bear-engine/core/src/visual/code/gl_renderer.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,8 @@ namespace bear
( const gl_fragment_shader& f, const gl_vertex_shader& v );
static void log_program_errors
( const std::string& step, GLuint program_id );

static constexpr std::size_t screenshot_height_step = 16;
}
}
}
Expand Down Expand Up @@ -314,20 +316,23 @@ void bear::visual::gl_renderer::shot( claw::graphic::image& img )
const unsigned int h = p[3];

img.set_size( w, h );
const std::size_t pixels_count(w * h);

glReadPixels( 0, 0, w, h, GL_RGBA, GL_UNSIGNED_BYTE, m_screenshot_buffer );
glReadPixels
( 0, 0, w, h, GL_RGBA, GL_UNSIGNED_BYTE, m_screenshot_buffer.data() );
VISUAL_GL_ERROR_THROW();

for ( claw::graphic::rgba_pixel_8* it=m_screenshot_buffer;
it!=m_screenshot_buffer + pixels_count;
++it )
it->components.alpha = 255;
for ( claw::graphic::rgba_pixel_8& p : m_screenshot_buffer )
p.components.alpha = 255;

auto begin( m_screenshot_buffer.begin() );
auto end( begin + w );

for (unsigned int y=0; y!=h; ++y)
std::copy( m_screenshot_buffer + y * w,
m_screenshot_buffer + (y+1) * w,
img[h - y - 1].begin() );
for ( unsigned int y( 0 ); y != h; ++y )
{
std::copy( begin, end, img[ h - y - 1 ].begin() );
begin += w;
end += w;
}

release_context();
} // gl_renderer::shot()
Expand Down Expand Up @@ -531,7 +536,6 @@ void bear::visual::gl_renderer::stop()
delete m_render_thread;
}

delete[] m_screenshot_buffer;
delete m_draw;

SDL_GL_DeleteContext( m_gl_context );
Expand Down Expand Up @@ -589,11 +593,11 @@ void bear::visual::gl_renderer::render_loop()

const systime::milliseconds_type start_date( systime::get_date_ms() );

if ( !m_screenshot_signal.empty() )
dispatch_screenshot();

if ( !m_pause )
render_states();
{
render_states();
update_screenshot();
}

const systime::milliseconds_type end_date( systime::get_date_ms() );

Expand Down Expand Up @@ -638,6 +642,19 @@ void bear::visual::gl_renderer::draw_scene()
boost::mutex::scoped_lock gl_lock( m_mutex.gl_access );
make_current();

draw_states();

if ( !m_screenshot_signal.empty() && !m_ongoing_screenshot )
draw_screenshot();

SDL_GL_SwapWindow( m_window );
VISUAL_GL_ERROR_THROW();

release_context();
}

void bear::visual::gl_renderer::draw_states()
{
set_background_color();

glClear( GL_COLOR_BUFFER_BIT );
Expand All @@ -652,12 +669,27 @@ void bear::visual::gl_renderer::draw_scene()

m_draw->finalize();
}
}

void bear::visual::gl_renderer::draw_screenshot()
{
m_ongoing_screenshot = true;
m_screenshot_line = 0;

SDL_GL_SwapWindow( m_window );
glBindFramebuffer( GL_FRAMEBUFFER, m_screenshot_frame_buffer );
VISUAL_GL_ERROR_THROW();

release_context();
} // gl_renderer::draw_scene()
glBindRenderbuffer( GL_RENDERBUFFER, m_screenshot_render_buffer );
VISUAL_GL_ERROR_THROW();

draw_states();

glBindRenderbuffer( GL_RENDERBUFFER, 0 );
VISUAL_GL_ERROR_THROW();

glBindFramebuffer( GL_FRAMEBUFFER, 0 );
VISUAL_GL_ERROR_THROW();
}

/*----------------------------------------------------------------------------*/
/**
Expand All @@ -667,6 +699,11 @@ void bear::visual::gl_renderer::set_background_color()
{
boost::mutex::scoped_lock lock( m_mutex.background_color );

if ( m_ongoing_screenshot )
{
glClearColor( 1, 0, 0, 1);
return;
}
const GLfloat max
( std::numeric_limits<claw::graphic::rgb_pixel::component_type>::max() );

Expand All @@ -687,6 +724,17 @@ void bear::visual::gl_renderer::resize_view
{
glViewport( 0, 0, viewport_size.x, viewport_size.y );
VISUAL_GL_ERROR_THROW();

m_viewport_size = viewport_size;

const std::size_t buffer_size( viewport_size.x * viewport_size.y );
m_screenshot_buffer.resize( buffer_size );
m_progressive_screenshot_buffer.resize( buffer_size );

m_progressive_screenshot_image.set_size( viewport_size.x, viewport_size.y );

m_ongoing_screenshot = false;
//update the framebuffer
} // gl_renderer::resize_view()

/*----------------------------------------------------------------------------*/
Expand Down Expand Up @@ -787,10 +835,6 @@ bool bear::visual::gl_renderer::ensure_window_exists()
<< ", vendor is " << glGetString(GL_VENDOR)
<< std::endl;

delete[] m_screenshot_buffer;
m_screenshot_buffer =
new claw::graphic::rgba_pixel_8[ m_window_size.x * m_window_size.y ];

SDL_ShowCursor(0);

#ifdef _WIN32
Expand All @@ -801,15 +845,47 @@ bool bear::visual::gl_renderer::ensure_window_exists()
<< glewGetErrorString(err) << std::endl;
#endif

resize_view( m_window_size );

glEnable(GL_BLEND);
VISUAL_GL_ERROR_THROW();

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
VISUAL_GL_ERROR_THROW();
m_draw = new gl_draw();

// setup the render buffer
glGenRenderbuffers( 1, &m_screenshot_render_buffer );
VISUAL_GL_ERROR_THROW();

glBindRenderbuffer( GL_RENDERBUFFER, m_screenshot_render_buffer );
VISUAL_GL_ERROR_THROW();

glRenderbufferStorage
( GL_RENDERBUFFER, GL_RGBA4, m_window_size.x, m_window_size.y );
VISUAL_GL_ERROR_THROW();

glBindRenderbuffer( GL_RENDERBUFFER, 0 );

// setup the frame buffer
glGenFramebuffers( 1, &m_screenshot_frame_buffer );
VISUAL_GL_ERROR_THROW();

glBindFramebuffer( GL_FRAMEBUFFER, m_screenshot_frame_buffer );
VISUAL_GL_ERROR_THROW();

glFramebufferRenderbuffer
( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER,
m_screenshot_render_buffer );
VISUAL_GL_ERROR_THROW();

assert
( glCheckFramebufferStatus( GL_FRAMEBUFFER ) == GL_FRAMEBUFFER_COMPLETE );
VISUAL_GL_ERROR_THROW();

glBindFramebuffer( GL_FRAMEBUFFER, 0 );
VISUAL_GL_ERROR_THROW();

resize_view( m_window_size );

release_context();

m_mutex.gl_access.unlock();
Expand Down Expand Up @@ -963,14 +1039,68 @@ bear::visual::gl_renderer::get_best_screen_size
return result;
} // gl_renderer::get_best_screen_size()

void bear::visual::gl_renderer::update_screenshot()
{
if ( !m_ongoing_screenshot )
return;

if ( m_screenshot_signal.empty() )
{
m_ongoing_screenshot = false;
return;
}

boost::mutex::scoped_lock gl_lock( m_mutex.gl_access );
make_current();

glBindFramebuffer( GL_FRAMEBUFFER, m_screenshot_frame_buffer );
VISUAL_GL_ERROR_THROW();

const std::size_t height
( std::min
( m_viewport_size.y - m_screenshot_line,
detail::screenshot_height_step ) );

claw::graphic::rgba_pixel_8* const output
( m_progressive_screenshot_buffer.data()
+ m_viewport_size.x * m_screenshot_line );

glReadPixels
( 0, m_screenshot_line, m_viewport_size.x, height, GL_RGBA,
GL_UNSIGNED_BYTE, output );
VISUAL_GL_ERROR_THROW();

glBindFramebuffer( GL_FRAMEBUFFER, 0 );
VISUAL_GL_ERROR_THROW();

release_context();

m_screenshot_line += height;

if ( m_screenshot_line == m_viewport_size.y)
dispatch_screenshot();
}

void bear::visual::gl_renderer::dispatch_screenshot()
{
m_ongoing_screenshot = false;

boost::signals2::signal< void( const claw::graphic::image& ) > signal;
signal.swap( m_screenshot_signal );

claw::graphic::image result;
shot( result );
signal( result );
auto begin( m_progressive_screenshot_buffer.begin() );
auto end( begin + m_viewport_size.x );

for ( unsigned int y( 0 ); y != m_viewport_size.y; ++y )
{
std::copy
( begin, end,
m_progressive_screenshot_image[ m_viewport_size.y - y - 1 ].begin() );
begin += m_viewport_size.x;
end += m_viewport_size.x;
}

signal( m_progressive_screenshot_image );
}

GLuint
Expand All @@ -996,7 +1126,7 @@ bear::visual::gl_renderer::gl_renderer()
m_view_size( 640, 480 ), m_fullscreen( false ),
m_video_mode_is_set( false ),
m_render_ready( false ),
m_screenshot_buffer( NULL ),
m_ongoing_screenshot( false ),
m_draw( NULL )
{
m_mutex.gl_access.lock();
Expand Down
17 changes: 14 additions & 3 deletions bear-engine/core/src/visual/gl_renderer.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -105,11 +105,13 @@ namespace bear

void render_states();
void draw_scene();
void draw_states();
void draw_screenshot();

void set_background_color();

void resize_view( const screen_size_type& viewport_size );

void make_current();
void release_context();

Expand All @@ -128,6 +130,7 @@ namespace bear
get_best_screen_size
( const std::vector<SDL_DisplayMode>& modes ) const;

void update_screenshot();
void dispatch_screenshot();

GLuint create_shader( GLenum type, const std::string& p );
Expand Down Expand Up @@ -160,6 +163,7 @@ namespace bear

/** \brief The size of the view on the rendered elements. */
screen_size_type m_view_size;
screen_size_type m_viewport_size;

/** \brief The title of the window. */
std::string m_title;
Expand All @@ -178,10 +182,17 @@ namespace bear

/** \brief A buffer in which we do the screenshots, to avoid an allocation
at each call. */
claw::graphic::rgba_pixel_8* m_screenshot_buffer;
std::vector< claw::graphic::rgba_pixel_8 > m_screenshot_buffer;
std::vector< claw::graphic::rgba_pixel_8 >
m_progressive_screenshot_buffer;
claw::graphic::image m_progressive_screenshot_image;
boost::signals2::signal< void( const claw::graphic::image& ) >
m_screenshot_signal;

GLuint m_screenshot_frame_buffer;
GLuint m_screenshot_render_buffer;
std::size_t m_screenshot_line;
bool m_ongoing_screenshot;

gl_draw* m_draw;
shader_program m_shader;

Expand Down

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