Jump to content

  • Log In with Google      Sign In   
  • Create Account

Banner advertising on our site currently available from just $5!

1. Learn about the promo. 2. Sign up for GDNet+. 3. Set up your advert!


Member Since 18 May 2012
Offline Last Active Mar 03 2015 04:00 AM

Topics I've Started

Water and erosion

15 April 2013 - 05:34 AM



Im currently trying to update my terrain engine to use water flow and erosion simulation in realtime.

I found this exelent example of it here: 




However I cant seme to recreate it in unity 3D. The description is a bit confusing. I have tried everything but cant get it to work.

The source code is a bit confusing as well so I have had no luck with that either.


Could someone who might understand be kind to help me figure out the algoritm or explain it?

GS Geometry from texture?

05 June 2012 - 02:20 AM

I resently read about geometry shaders but I only found examples where you pass vertex data to the GS and then create new geometry. I was thinking is it possible to not give the geometry shader any vertrices and have it create new ones by reading a texture? So that the only thing I have to do is give the shader a texture and out comes some nice looking terrain.

If there is? Is there any tutorials or something where I can read about it?

DirectX9 Hardware Instancing. Draws only one instance?

18 May 2012 - 03:42 PM


This is my first post on this site. I used to be at App Hub but I resently started working directly to DirectX and the DirectX activity there is close to none thats why I joined here so that I might have someone to talk to. But enoght about that and on to my question.

For a few days I have tried to get hardware instancing to work but with no luck. I have googled a lot and read everything on the topic that I can find. Everything compiles and It draws one of the instances where only one of the vertrices are affected by the world coordinate. I'm at the point where I want to throw the computer out the window so please have a look at this and help me if you can!

Here is the instancing parts of my code.

private int _instanceCount;

private InstanceFormat[] _instances;

private VertexBuffer _instanceBuffer;

private int _vertexCount;

private VertexFormat[] _vertices;

private VertexBuffer _vertexBuffer;

private int _indexCount;

private uint[] _indices;

private IndexBuffer _indexBuffer;

private D3D.Effect _instancingEffect;

private VertexDeclaration _vertexDeclaration;

int vertexSize;

int instanceSize;

struct VertexFormat


public Vector3 Position;

public Vector2 Texture;

public VertexFormat(Vector3 position, Vector2 texture)


Position = position;

Texture = texture;



struct InstanceFormat


public Vector3 World;

public InstanceFormat(Vector3 world)


World = world;



This is where I create my Declaration and fill the buffers:
#region Set up vertex declaration

vertexSize = 20;

instanceSize = 12;

VertexElement[] vertexElementsArray = new VertexElement[]


new VertexElement(0, 0, DeclarationType.Float3, DeclarationMethod.Default, DeclarationUsage.Position, 0),

new VertexElement(0, 12, DeclarationType.Float2, DeclarationMethod.Default, DeclarationUsage.TextureCoordinate, 0),

new VertexElement(1, 0, DeclarationType.Float4, DeclarationMethod.Default, DeclarationUsage.TextureCoordinate, 1),



// Create a vertex declaration based on the vertex elements.

_vertexDeclaration = new VertexDeclaration(_device, vertexElementsArray);


#region Set up vertex buffer for vertices

_vertexCount = 4;

_vertexBuffer = new VertexBuffer(_device, vertexSize*_vertexCount, Usage.Dynamic | Usage.WriteOnly, VertexFormats.Position | VertexFormats.Texture0, Pool.Default);

_vertices = new VertexFormat[_vertexCount];

_vertices[0] = new VertexFormat(new Vector3(0, 0, 0), new Vector2(0, 0));

_vertices[1] = new VertexFormat(new Vector3(0, 1, 0), new Vector2(0, 1));

_vertices[2] = new VertexFormat(new Vector3(1, 0, 0), new Vector2(1, 0));

_vertices[3] = new VertexFormat(new Vector3(1, 1, 0), new Vector2(1, 1));

_vertexBuffer.SetData(_vertices, 0, LockFlags.None);


#region Set up index buffer

_indexCount = 6;

_indexBuffer = new IndexBuffer(_device, sizeof(uint)*_indexCount, Usage.WriteOnly, Pool.Default, false);

_indices = new uint[_indexCount];

_indices[0] = 0; _indices[1] = 1; _indices[2] = 2;

_indices[3] = 1; _indices[4] = 3; _indices[5] = 2;

_indexBuffer.SetData(_indices, 0, LockFlags.None);


#region Set up vertex buffer for instances

_instanceCount = 10;

_instanceBuffer = new VertexBuffer(_device, instanceSize * _instanceCount, Usage.Dynamic | Usage.WriteOnly, VertexFormats.None, Pool.Default);

_instances = new InstanceFormat[_instanceCount];

for (int i = 0; i < _instanceCount; i++)

_instances[i] = new InstanceFormat(new Vector3(i, 0, i));

_instanceBuffer.SetData(_instances, 0, LockFlags.None);


And this is my draw method:
_device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.DarkSlateBlue, 1.0f, 0);


_device.VertexDeclaration = _vertexDeclaration;

_device.Indices = _indexBuffer;

_device.SetStreamSource(0, _vertexBuffer, 0, vertexSize);

_device.SetStreamSource(1, _instanceBuffer, 0, instanceSize);

// Specify how many times the vertex stream source and the instance stream source should be rendered.

_device.SetStreamSourceFrequency(0, _instanceCount);

_device.SetStreamSourceFrequency(1, 1);

_instancingEffect.Technique = "Instancing";

_instancingEffect.SetValue("WVP", _camera.view * _camera.projection);

_instancingEffect.SetValue("cubeTexture", _textures[1]);

int numpasses = _instancingEffect.Begin(0);

for (int i = 0; i < numpasses; i++)



_device.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertexCount, 0, _indexCount / 3);




_device.SetStreamSourceFrequency(0, 1);

_device.SetStreamSourceFrequency(1, 1);



And here is my shader:
float4x4 WVP;

texture cubeTexture;

sampler TextureSampler = sampler_state


texture = <cubeTexture>;

mipfilter = LINEAR;

minfilter = LINEAR;

magfilter = LINEAR;


struct InstancingVSinput


float4 Position : POSITION0;

float2 TexCoord : TEXCOORD0;

float4 World : TEXCOORD1;


struct InstancingVSoutput


float4 Position : POSITION0;

float2 TexCoord : TEXCOORD0;


InstancingVSoutput InstancingVS(InstancingVSinput input)


InstancingVSoutput output;

// Transform the vertex into world coordinates.

float4 pos = input.Position + input.World;

// Transform the vertex from world coordinates into screen coordinates.

output.Position = mul(pos, WVP);

output.TexCoord = input.TexCoord;

return output;


float4 InstancingPS(InstancingVSoutput input) : COLOR0


return float4(1,1,1,1);// tex2D(TextureSampler, input.TexCoord);


technique Instancing


pass Pass0


VertexShader = compile vs_3_0 InstancingVS();

PixelShader = compile ps_3_0 InstancingPS();



Edit: I should probably mention that I have a Radeon HD 5770.