When body's background color is set as transparent as below, the actual background is displayed as purple in cobalt.
body {
background-color: transparent;
}
Is there any way to make background to be real transparent? I wish to show other gfx or video layers under cobalt's graphics layer. Thanks!
As an optimization, Cobalt does not clear its framebuffer each frame, however this can indeed cause a problem if you would like to use it as an overlay.
In cobalt/renderer/pipeline.cc, right after the line:
rasterizer::Rasterizer::Options rasterizer_options;
but before the line:
rasterizer_->Submit(results.animated, render_target, rasterizer_options);
If you add:
rasterizer_options.flags = rasterizer::Rasterizer::kSubmitFlags_Clear;
Cobalt will clear each frame to be fully transparent before rendering the contents.
We will look into adding a nicer way to express this desire in the future, but hopefully this helps for now.
So comment out the following line from src/cobalt/renderer/backend/egl/graphics_context.cc:GraphicsContextEGL::SecurityClear()
GL_CALL(glClearColor(1.0f, 0.4f, 1.0f, 1.0f));
