EGL Context antialiasing bug

[DanielDorn]

Once again a bug in the EGL Context class now effecting antialiasing

This bug effects all versions of SFML supporting android,

to recreate this bug simply use the following code with the current version of sfml

int main(int argc, char* argv[])
{
	::tiny::RenderWindow window(::tiny::VideoMode(200, 200), "tiny works!", ::tiny::Style::Default, ::tiny::ContextSettings{ 32, 0, 4, 1, 1, ::tiny::ContextSettings::Default, false });
	window.setActive(true);
	::tiny::CircleShape shape(100.f);
	shape.setFillColor(::tiny::Color::Green);
	bool isDone = false;
	
	
	while(isDone == false)
	{
		::tiny::Event event;
		while (window.pollEvent(event))
		{
			if (event.type == ::tiny::Event::Closed)
			{
				window.close();
				isDone = true;
			}

			if(event.type == ::tiny::Event::GainedFocus)
				::tiny::err() << "Gained Focus" << ::std::endl;
		}

		window.clear();
		window.draw(shape);
		window.display();
	}

	return 0;
}

Because we have set the antialiasing level to 4 it will draw nothing to the screen because of the following lines of bugged code in EglContext.cpp

EGLConfig EglContext::getBestConfig(EGLDisplay display, unsigned int bitsPerPixel, const ContextSettings& settings)
{
	// Set our video settings constraint
	const EGLint attributes[] = {
		EGL_BUFFER_SIZE, static_cast<EGLint>(bitsPerPixel),
		EGL_DEPTH_SIZE, static_cast<EGLint>(settings.depthBits),
		EGL_STENCIL_SIZE, static_cast<EGLint>(settings.stencilBits),
		EGL_SAMPLE_BUFFERS, static_cast<EGLint>(settings.antialiasingLevel),
		EGL_SURFACE_TYPE, EGL_WINDOW_BIT | EGL_PBUFFER_BIT,
		EGL_RENDERABLE_TYPE, EGL_OPENGL_ES_BIT,
		EGL_NONE
	};

	EGLint configCount;
	EGLConfig configs[1];

	// Ask EGL for the best config matching our video settings
	eglCheck(eglChooseConfig(display, attributes, configs, 1, &configCount));

	// TODO: This should check EGL_CONFORMANT and pick the first conformant configuration.

	return configs[0];
}

the bug coming from the getBestConfig function is caused because of incorrectly set attributes, EGL_SAMPLE_BUFFERS is not where we set the multisamples but rather the number of buffers for multisampling, currently EGL only support a value between 0 and 1, anything more then 1 will caused undefined behavior,

patch

EGLConfig EglContext::getBestConfig(EGLDisplay display, unsigned int bitsPerPixel, const ContextSettings& settings)
{
	EGLint multiSamplesBuffer = 0;

	if(settings.antialiasingLevel > 0)
		multiSamplesBuffer = 1;
		
	// Set our video settings constraint
	const EGLint attributes[] = {
		EGL_BUFFER_SIZE, static_cast<EGLint>(bitsPerPixel),
		EGL_DEPTH_SIZE, static_cast<EGLint>(settings.depthBits),
		EGL_STENCIL_SIZE, static_cast<EGLint>(settings.stencilBits),
		EGL_SAMPLE_BUFFERS, multiSamplesBuffer,
		EGL_SAMPLES, static_cast<EGLint>(settings.antialiasingLevel),
		EGL_SURFACE_TYPE, EGL_WINDOW_BIT | EGL_PBUFFER_BIT,
		EGL_RENDERABLE_TYPE, EGL_OPENGL_ES_BIT,
		EGL_NONE
	};

	EGLint configCount;
	EGLConfig configs[1];

	// Ask EGL for the best config matching our video settings
	eglCheck(eglChooseConfig(display, attributes, configs, 1, &configCount));

	// TODO: This should check EGL_CONFORMANT and pick the first conformant configuration.

	return configs[0];
}

this patch simply checks if antialiasing is enabled and sets a the samples buffer on or off accordingly, hope this helps anyone with this issue, cheers (=

[binary1248]

This should be fixed with #1534.