Create Circle Mesh

[floxXx]

I want to make a circle Mesh by setting 2 parameters ( radius and tileCount)

How to draw the Mesh?

There is already a function addSphereMesh(..) but this is a Sphere and not a circle.

Please leave some code here.


Functions:
alpha = 360 / tileCount;
CoordX = sin(alpha) * r;
CoordZ = cos(alhpa) * r;
CoordY = 0;

The Type should be IAnimatedMesh in the end.

[randomMesh]

Code: Select all

irr::scene::SMeshBuffer* createCircleFan(irr::u32 verts, irr::f32 radius, const irr::video::SColor& color)
{
	if (verts < 3)
		verts = 3;
	else if (65534 < verts)
		verts = 65534;

	irr::scene::SMeshBuffer* mb = new irr::scene::SMeshBuffer;
	if (!mb)
		return 0;

	irr::video::S3DVertex vertex;
	vertex.Normal.set(0, 1, 0);
	vertex.Color = color;

	// origin vertex
	vertex.Pos.set(0, 0, 0);
	vertex.TCoords.set(.5f, .5f);
	mb->Vertices.push_back(vertex);
	mb->Indices.push_back(0);

	for (irr::s32 n = verts; 0 <= n; --n)
	{
		const irr::f32 x = (irr::core::PI*2.f)*n/verts;

		const irr::f32 dx = sinf(x);
		const irr::f32 dz = cosf(x);

		// vertices are always in the xz plane
		vertex.Pos.set(dx*radius, 0, dz*radius);

		// scale tcoords from -1,1 to 0,1
		vertex.TCoords.set((dx + 1.f) * .5f, (dz + 1.f) * .5f);

		mb->Vertices.push_back(vertex);
		mb->Indices.push_back(n + 1);
	}

	return mb;
}

Draw the meshbuffer like this

Code: Select all

//don't forget to set material and transformation
      driver->drawIndexedTriangleFan( 
         (irr::video::S3DVertex*)circleBuffer->getVertices(), 
         circleBuffer->getVertexCount(), 
         &circleBuffer->getIndices()[0], 
         circleBuffer->getIndexCount() - 2);

Edit:
Removed wrong advice about MeshSceneNode :p

[Acki]

there is already something like this in the forum:
http://irrlicht.sourceforge.net/phpBB2/ ... 032#211032

[floxXx]

Danke dir,

wenn sämtliche Einträge : "mb->Indices.push_back(..)"
gelöscht werden und nacher :

Code: Select all

for (irr::s32 n = vertices; 1<=n; --n)
   {
		mb->Indices.push_back(0);
		mb->Indices.push_back(n+1);
		mb->Indices.push_back(n);
   }

eingefügt funktioniert es.
Danke dir

[randomMesh]

Code: Select all

int main()
{
	IrrlichtDevice* device = createDevice(video::EDT_OPENGL);
	irr::video::IVideoDriver* driver = device->getVideoDriver();
	irr::scene::ISceneManager* smgr = device->getSceneManager();

	smgr->addCameraSceneNodeFPS();

	irr::scene::IMeshBuffer* circleBuffer = createCircleFan(64, 50.0f, irr::video::SColor(255, 255, 255, 255));
	circleBuffer->recalculateBoundingBox();
	circleBuffer->setHardwareMappingHint(irr::scene::EHM_STATIC);

	irr::video::SMaterial mat;
	mat.Lighting = false;

	while (device->run())
	{
		driver->beginScene();
		smgr->drawAll();

		driver->setMaterial(mat);
		driver->setTransform(irr::video::ETS_WORLD, irr::core::IdentityMatrix);
		driver->drawIndexedTriangleFan(
			(irr::video::S3DVertex*)circleBuffer->getVertices(),
			circleBuffer->getVertexCount(),
			&circleBuffer->getIndices()[0],
			circleBuffer->getIndexCount() - 2);


		driver->endScene();
	}

	circleBuffer->drop();
	device->drop();

	return 0;
}

works without modification.

[floxXx]

One more question / bug?

For test issues I use the Realisic Water Scene Node from this Forum on the circle Mesh.

But if I rotate the Camera, the water sometimes disappears. Move the camera and the water is visible again.

Is there a bug in my Circle Mesh or does the shader crashes with my mesh in a specific camera angle for some reasons beingt in the water shader from the Realisitic Water Scene Node? (hlsl)

Code RealisticWaterSceneNode

Code: Select all

RealisticWaterSceneNode::RealisticWaterSceneNode(scene::ISceneManager* sceneManager,video::ITexture* bumpTexture,
												f32 radius, f32 vertices, bool WavesToCenter,
												ITimer* timer, core::dimension2di renderTargetSize,
												scene::ISceneNode* parent, s32 id):
	scene::ISceneNode( parent?parent:sceneManager->getRootSceneNode(), sceneManager, id),
	Timer(timer), Size(radius,radius), SceneManager(sceneManager), RefractionMap(0), ReflectionMap(0),
	WindForce(20.0f),WindDirection(0,1),WaveHeight(0.3f), WaterColor(0.1f, 0.1f, 0.6f, 1.0f), ColorBlendFactor(0.2f), Camera(0)
{
	VideoDriver = SceneManager->getVideoDriver();

	scene::ICameraSceneNode* CurrentCamera=SceneManager->getActiveCamera(); //get current camera
	Camera=SceneManager->addCameraSceneNode(); //create new camera

    Camera->setFarValue(CurrentCamera->getFarValue());
	Camera->setFOV(CurrentCamera->getFOV());
	SceneManager->setActiveCamera(CurrentCamera); //set back the previous camera	

	
   if (vertices < 3) 
      vertices = 3; 
   else if (65534 < vertices) 
      vertices = 65534; 

   irr::scene::SMeshBuffer* mb = new irr::scene::SMeshBuffer; 
 
   irr::video::S3DVertex vertex; 
   vertex.Normal.set(0, 1, 0); 
   vertex.Color.setAlpha(WaterColor.a); 
   vertex.Color.setBlue(WaterColor.b); 
   vertex.Color.setGreen(WaterColor.g); 
   vertex.Color.setRed(WaterColor.r); 

   // origin vertex 
   vertex.Pos.set(0, 0, 0); 
   vertex.TCoords.set(.5f, .5f); 
   mb->Vertices.push_back(vertex); 

   for (irr::s32 n = vertices; 0 <= n; --n) 
   { 
      const irr::f32 x = (irr::core::PI*2.f)*n/vertices; 

      const irr::f32 dx = sinf(x); 
      const irr::f32 dz = cosf(x); 

      // vertices are always in the xz plane 
      vertex.Pos.set(dx*radius, 0, dz*radius); 

      // scale tcoords from -1,1 to 0,1 
      vertex.TCoords.set((dx + 1.f) * .5f, (dz + 1.f) * .5f); 

      mb->Vertices.push_back(vertex); 
   } 
   for (irr::s32 n = vertices; 1<=n; --n)
   {
		mb->Indices.push_back(0);
		mb->Indices.push_back(n+1);
		mb->Indices.push_back(n);
   }


   scene::SMesh *WaterMesh = new scene::SMesh; 
   WaterMesh->addMeshBuffer(mb); 
   mb->drop(); 
   WaterMesh->recalculateBoundingBox(); 

	WaterSceneNode=SceneManager->addMeshSceneNode(WaterMesh,this);
	
	video::IGPUProgrammingServices* GPUProgrammingServices = VideoDriver->getGPUProgrammingServices();

	std::string WaterPixelShader;
	std::string WaterVertexShader;

	if (VideoDriver->getDriverType()==video::EDT_DIRECT3D9)
	{
		WaterPixelShader="shaders/Water_ps.hlsl";
		WaterVertexShader="shaders/Water_vs.hlsl";
	}
	else if (VideoDriver->getDriverType()==video::EDT_OPENGL)
	{
		WaterPixelShader="shaders/Water_ps.glsl";
		WaterVertexShader="shaders/Water_vs.glsl";
	}

	ShaderMaterial=GPUProgrammingServices->addHighLevelShaderMaterialFromFiles(
		WaterVertexShader.c_str(),"main",video::EVST_VS_1_1,
		WaterPixelShader.c_str(),"main",video::EPST_PS_2_0,
		this,video::EMT_LIGHTMAP);

	WaterSceneNode->setMaterialType((video::E_MATERIAL_TYPE)ShaderMaterial);

	WaterSceneNode->setMaterialTexture(0,bumpTexture);

	irr::core::dimension2d<u32> renderSize;
	renderSize.set(renderTargetSize.Width,renderTargetSize.Height);
	RefractionMap=VideoDriver->addRenderTargetTexture(renderSize);
	ReflectionMap=VideoDriver->addRenderTargetTexture(renderSize);
	WaterSceneNode->setMaterialTexture(1,RefractionMap);
	WaterSceneNode->setMaterialTexture(2,ReflectionMap);
}

[hybrid]

The code from randomMesh requires that the mesh is rendered as tri-fan. This won't work with the dfault mesh scene node. If the latter is intended (which is probably also required for the water scene node), you need to use the full index set. However, you will also need a proper bbox then, which needs to be created in the meshbuffer, and the updated in the SMesh and the mesh scene node via updateBoundingBox.

[floxXx]

and what does that mean?

[hybrid]

That the error with the water node might be fixed when using your way of adding the indices, and adding several updateBoundingBox calls where necessary. You might also have to add the vertices to the mehsbuffer's bbox in order to get a proper init.

[floxXx]

hybrid thank you so much

add:
mb->recalculateBoundingBox();

[netpipe]

randomMesh i try your circle code with 1.7 and nothing shows up.

[randomMesh]

This is a flat disk (like planet earth). Remember to disable backface culling if you want to see it from behind. Or just move the camera.

Code: Select all

camera->setPosition(irr::core::vector3df(0.0, 50.0,-10));

works well.