day and night world map [solved]

[milkshakeman]

Hi,

I'm trying to create a day/night world map effect, like on this site:
http://www.timeanddate.com/worldclock/sunearth.html

So there is one day texture in the background, and a night texture on top with a transparency mask that offsets horizontally depending on the time of the day.

Anybody an idea what the best approach would be to achieve this using irrLicht?


Thanks

[randomMesh]

This has been discussed before, using the search function might help.
e.g. http://irrlicht.sourceforge.net/phpBB2/viewtopic.php?t=28931

Additionally, there's a RTTSkyBoxSceneNode in the irrExt repository.

[milkshakeman]

While the solution with the directional light simulating the sun is nice, but first of all it only works good in 3D when rendering the world as a sphere, and I'm working in 2D, rendering the world as a flat plane.
And the real earth night texture with all the city-lights looks nicer than just creating a shadow.

[hybrid]

Either use two planes one over the other, or use the solid_2texture material. Then you need to change the vertex alpha to blend between the two textures.

[milkshakeman]

Thanks hybrid, I got it to work with that second method you suggested.
I even used a sphere, which was a bit tricky.

Anyway, below is my code, not cleaned up or optimised but if anyone ever wanted to update one half of a sphere's vertices alpha, it may help to have a look.

Code: Select all

	polycount=512;
	// add the node
	globe = smgr->addSphereSceneNode(10,polycount);
	// add the textures
	globe->setMaterialTexture(0, graphics->driver->getTexture("media/Earth.png"));
	globe->setMaterialTexture(1, graphics->driver->getTexture("media/EarthNight.png"));
	//globe->setMaterialFlag( video::EMF_WIREFRAME, true );
	globe->setMaterialFlag( video::EMF_LIGHTING, false );
	globe->setMaterialType( video::EMT_SOLID_2_LAYER );
	setGlobeDayNightOffset(0);

Code: Select all

void setGlobeDayNightOffset(int degrees)
{
	int oS,oE;
	if (degrees>180){
		oS=(degrees*(polycount+1))/360;
		oE=oS-((polycount+1)/2);
	}else{
		oS=(degrees*(polycount+1))/360;
		oE=oS+((polycount+1)/2);
	}

	// set all vertices to 0 alpha
	smgr->getMeshManipulator()->setVertexColorAlpha(globe->getMesh(),0);
	// run through the vertices and update the alpha
	// on one half of the sphere
	int meshBufferCount = globe->getMesh()->getMeshBufferCount();
	for (int mb=0;mb<meshBufferCount;mb++)
	{
		S3DVertex* v = (S3DVertex*)globe->getMesh()->getMeshBuffer(mb)->getVertices();
		int cnt = globe->getMesh()->getMeshBuffer(mb)->getVertexCount();
		int slice=0;
		for (int i=0;i<globe->getMesh()->getMeshBuffer(mb)->getVertexCount();i++)
		{
			if (oE<oS){
				if ((slice>=0 && slice <oE) || (slice>=oS && slice <(polycount+1)))
					v[i].Color.setAlpha(255);
			}else{
				if (slice>=oS && slice <oE)
					v[i].Color.setAlpha(255);
			}
			slice++;
			if (slice==polycount){
				slice=0;
				i++;
				v[i].Color.setAlpha(v[i-1].Color.getAlpha());
			}
		}
	}
}