void ShaderToyApp::draw()
{
// Bind textures.
if( mChannel0 ) mChannel0->bind( 0 );
if( mChannel1 ) mChannel1->bind( 1 );
if( mChannel2 ) mChannel2->bind( 2 );
if( mChannel3 ) mChannel3->bind( 3 );
// Render the current shader to a frame buffer.
if( mShaderCurrent && mBufferCurrent ) {
gl::ScopedFramebuffer fbo( mBufferCurrent );
// Bind shader.
gl::ScopedGlslProg shader( mShaderCurrent );
setUniforms();
// Clear buffer and draw full screen quad (flipped).
gl::clear();
gl::drawSolidRect( Rectf( 0, (float)getWindowHeight(), (float)getWindowWidth(), 0 ) );
}
// Render the next shader to a frame buffer.
if( mShaderNext && mBufferNext ) {
gl::ScopedFramebuffer fbo( mBufferNext );
// Bind shader.
gl::ScopedGlslProg shader( mShaderNext );
setUniforms();
// Clear buffer and draw full screen quad (flipped).
gl::clear();
gl::drawSolidRect( Rectf( 0, (float)getWindowHeight(), (float)getWindowWidth(), 0 ) );
}
// Perform a cross-fade between the two shaders.
double time = getElapsedSeconds() - mTransitionTime;
double fade = math<double>::clamp( time / mTransitionDuration, 0.0, 1.0 );
if( fade <= 0.0 ) {
// Transition has not yet started. Keep drawing current buffer.
gl::draw( mBufferCurrent->getColorTexture(), getWindowBounds() );
}
else if( fade < 1.0 ) {
// Transition is in progress.
// Use a transition shader to avoid having to draw one buffer on top of another.
gl::ScopedTextureBind tex0( mBufferCurrent->getColorTexture(), 0 );
gl::ScopedTextureBind tex1( mBufferNext->getColorTexture(), 1 );
gl::ScopedGlslProg shader( mShaderTransition );
mShaderTransition->uniform( "iSrc", 0 );
mShaderTransition->uniform( "iDst", 1 );
mShaderTransition->uniform( "iFade", (float)fade );
gl::drawSolidRect( getWindowBounds() );
}
else if( mShaderNext ) {
// Transition is done. Swap shaders.
gl::draw( mBufferNext->getColorTexture(), getWindowBounds() );
mShaderCurrent = mShaderNext;
mShaderNext.reset();
mPathCurrent = mPathNext;
mPathNext.clear();
getWindow()->setTitle( std::string( "ShaderToyApp - Showing " ) + mPathCurrent.filename().string() );
}
else {
// No transition in progress.
gl::draw( mBufferCurrent->getColorTexture(), getWindowBounds() );
}
}
