Why I only get the botton half of image as a result?

Using Cinder
1

I am trying to render into fbo and than write it to file, but sadly I only get botton half of image, … not sure what’s going on or what should be next steps.

fbo_out
fbo_out1024×1024 2.99 KB 

void draw_the_thing()
{
	

	const bool display = false;

	gl::FboRef myFbo = gl::Fbo::create(1024, 1024);

	myFbo->bindFramebuffer();
	//<...drawing commands...>
	
	//ci::gl::translate(0, -150);

	ci::gl::clear();
	ci::gl::color(0.1f, 0.9f, 0.1f);
	
	//ci::gl::drawSolidRect(ci::Rectf(0.0f, 0, -1024.0f, height_fbo / 4), glm::vec2(-1.0, 1.0f), glm::vec2(-1.0f, 1.0f));
	//ci::gl::drawSolidRect(ci::Rectf(0, 1024.0f * 0.25f, 1024.0f * 0.25f, 0));

	//ci::gl::drawSolidRect()
	//ci::gl::drawSolidRect(ci::Rectf(0, -1024.0f, 1024.0f * 0.25f, 1024.0f * 2.0f));
	//ci::gl::drawLine(glm::vec2(0.0f, 0.0f), glm::vec2(1024.0f, 1024.0f));
	ci::Rectf rect1 = ci::Rectf(0.0f, 100.0f, 500.0f, 200.0f);
	ci::gl::drawSolidRect(rect1);

	ci::Rectf rect2 = ci::Rectf(0.0f, 300.0f, 500.0f, 400.0f);
	ci::gl::drawSolidRect(rect2);


	ci::Rectf rect3 = ci::Rectf(0.0f, -300.0f, 500.0f, -400.0f);
	ci::gl::drawSolidRect(rect3);

	ci::Rectf rect4= ci::Rectf(0.0f, -400.0f, 500.0f, -300.0f);
	ci::gl::drawSolidRect(rect4);

	for (int i = 0; i < 100; i++)
	{
		float offset_x = 512.0f;
		float offset_y = 100.0f;

		float x1 = offset_x + 100.0f * sinf(i * 0.01f * 3.1415f * 2.0f);
		float y1 = offset_y + 100.0f * cosf(i * 0.01f * 3.1415f * 2.0f);
		
		float x2 = offset_x + 0.0f;
		float y2 = offset_y + 0.0f;


		ci::gl::drawLine(glm::vec2(x1, y1), glm::vec2(x2, y2));
	}

	for (int i = 0; i < 100; i++)
	{
		float offset_x = 512.0f;
		float offset_y = 0.0f;

		float x1 = offset_x + 100.0f * sinf(i * 0.01f * 3.1415f * 2.0f);
		float y1 = offset_y + 100.0f * cosf(i * 0.01f * 3.1415f * 2.0f);

		float x2 = offset_x + 0.0f;
		float y2 = offset_y + 0.0f;


		ci::gl::drawLine(glm::vec2(x1, y1), glm::vec2(x2, y2));
	}


	for (int i = 0; i < 100; i++)
	{
		float offset_x = 512.0f;
		float offset_y = -100.0f;

		float x1 = offset_x + 100.0f * sinf(i * 0.01f * 3.1415f * 2.0f);
		float y1 = offset_y + 100.0f * cosf(i * 0.01f * 3.1415f * 2.0f);

		float x2 = offset_x + 0.0f;
		float y2 = offset_y + 0.0f;


		ci::gl::drawLine(glm::vec2(x1, y1), glm::vec2(x2, y2));
	}

	ci::gl::drawLine(glm::vec2(0.0f, 0.0f), glm::vec2(1024.0f, 0.0f));
	ci::gl::drawLine(glm::vec2(0.0f, 10.0f), glm::vec2(1024.0f * 2.0f, 10.0f));

	myFbo->unbindFramebuffer();

	//Display

	if (display)
	{
		gl::draw(myFbo->getColorTexture());
	}
	



	std::filesystem::path path = "C:\\Users\\<the_user>\\Desktop\\test\\fbo_out.png";

	static bool to_save = true;
	if (to_save)
	{
		to_save = false;
		ci::writeImage(path, myFbo->getColorTexture()->createSource());
	}
	


	
}
2

You need to set your matrices / viewport to match the framebuffer you’re drawing into.

gl::FboRef myFbo = gl::Fbo::create ( 1024, 1024 );
gl::ScopedMatrices m;
gl::ScopedViewport vp { ivec2 ( 0 ), myFbo->getSize() };
gl::setMatricesWindow ( myFbo->getSize() );

// Draw calls here
1 Like
4

Thanks a lot this solved it!