bindFramebufferFace

filter.cpp

void BasicIBL::prefilterCubeMap()
{

	auto texFormat = gl::TextureCubeMap::Format();
	texFormat.setInternalFormat( GL_RGB );
	texFormat.enableMipmapping();
	texFormat.setMinFilter( GL_LINEAR_MIPMAP_LINEAR );
	texFormat.setMagFilter( GL_LINEAR );
	texFormat.setWrap( GL_CLAMP_TO_EDGE, GL_CLAMP_TO_EDGE );
	
	auto fboFormat = gl::FboCubeMap::Format().textureCubeMapFormat( texFormat );
	auto fbo = gl::FboCubeMap::create( 512, 512, fboFormat );

	auto shader = gl::GlslProg::create( loadAsset( "shaders/prefilter.vert" ), loadAsset( "shaders/prefilter.frag" ) );
	shader->uniform( "uCubeMapTex", 0 );
	shader->uniform( "uMaxLod", static_cast<float>( NUM_MIP_LEVELS ) );

	auto cube = gl::Batch::create( geom::Cube().size( vec3( 2.0 ) ), shader );
	
	gl::ScopedFramebuffer fboScp( fbo );
	gl::ScopedTextureBind texScp( mCubeMapTex );
	gl::ScopedMatrices mScp;

	ivec2 size = fbo->getSize();

	for( int level = 0; level < NUM_MIP_LEVELS; level++ ) {
		
		gl::ScopedViewport vpScp( ivec2( 0, 0 ), size );

		for( uint8_t dir = 0; dir < 6; ++dir ) {
			
			gl::setProjectionMatrix( ci::CameraPersp( size.x, size.y, 90.0f, 0.01f, 1000.0f ).getProjectionMatrix() );
			gl::setViewMatrix( fbo->calcViewMatrix( GL_TEXTURE_CUBE_MAP_POSITIVE_X + dir, vec3( 0 ) ) );

			GLuint id = fbo->getTextureCubeMap()->getId();
			glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + dir, id, level );

/*
			The following does not work
			fbo->bindFramebufferFace( GL_TEXTURE_CUBE_MAP_POSITIVE_X + dir, level );
*/
			shader->uniform( "uLod", static_cast<float>( level ) );
			
			gl::clear( Color::black() );
			cube->draw();
		}
		
		CI_LOG_V( "Mipmap level " << level << " generated at " << size );
		size /= 2;
	}
	
	mCubeMapFilteredTex = fbo->getTextureCubeMap();
}