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Migi0027

DX11 DX11 - Terrain Tessellation repeating

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Hi guys.

 

I've been trying to implement tessellation, and got it implemented, thanks to you.

 

My next goal is to implement terrain tessellation with displacement mapping

 

Questions: (Some I have attempted, shown in the shader code below)

  • The vertices generated on the cpu, do they just represent a plane, or a pre generated grid?
  • How do I decide the height of the displacement mapping, just a constant?
  • How are the normals generated?

My attempt: (If you want to see...)

cbuffer ConstantObjectBuffer : register (b0)
{
	matrix worldMatrix;
};

cbuffer ConstantFrameBuffer : register (b1)
{
	matrix viewMatrix;
	matrix projectionMatrix;

	float3 eyepos;
	float cppad;

	float4 lightvec;
	float4 lightcol;

	float FogStart;
	float FogEnd;
	float2 __space;

	float3 FogColor;
	float shadows;

	float SpecularIntensity;
	float3 pad3;
	float4 SpecularColor;
}


//***************************************************//
//                 VERTEX SHADER                     //
//***************************************************//

struct VOut
{
    float4 position : POSITION;
	float2 texcoord : TEXCOORD;
	float access : ACCESS;

	float tessAmount : TSSAM;
	
	float3 NormalW : NORMWORLD;
	float3 normal : NORM;
	float4 depthPosition : TEXTURE0;
};

struct GlobalIn
{
	float4 position : POSITION;
	float4 normal : NORMAL;
	float2 texcoord : TEXCOORD;
};

Texture2D t_map : register(t0);
SamplerState ss;

VOut VShader(GlobalIn input)
{
    VOut output;

    input.position.w = 1.0f;
	output.texcoord = input.texcoord;

	// Calculate the position of the vertex against the world, view, and projection matrices.
    /*output.position = mul(input.position, worldMatrix);
    output.position = mul(output.position, viewMatrix);
    output.position = mul(output.position, projectionMatrix);*/

	output.position = mul(input.position, viewMatrix);

	// Get Tesselation amount
	output.tessAmount = (1.0f / output.position.z) * 6.0f;

	output.position = input.position;

    output.NormalW = mul(float4(input.normal.xyz,0), mul(worldMatrix, viewMatrix));

	// Store the position value in a second input value for depth value calculations.
	output.depthPosition.xyz = mul(float4(input.position.xyz,1), mul(worldMatrix, viewMatrix)).xyz;

	// Per Vertex lighting
	float4 norm = normalize(input.normal);
	output.access = saturate(dot(norm, lightvec));

	output.normal = input.normal;
	
    return output;
}

//***************************************************//
//                 HULL SHADER                       //
//***************************************************//

struct HOutput
{
    float edges[3] : SV_TessFactor;
    float inside : SV_InsideTessFactor;
};

#define tessellationAmount 12.0f

HOutput ColorPatchConstantFunction(InputPatch<VOut, 3> inputPatch, uint patchId : SV_PrimitiveID)
{    
    HOutput output;

	float tA = inputPatch[0].tessAmount;
	tA = 12.0f;

    // Set the tessellation factors for the three edges of the triangle.
    output.edges[0] = tA;
    output.edges[1] = tA;
    output.edges[2] = tA;

    // Set the tessellation factor for tessallating inside the triangle.
    output.inside = tA;

    return output;
}

[domain("tri")]
[partitioning("integer")]
[outputtopology("triangle_cw")]
[outputcontrolpoints(3)]
[patchconstantfunc("ColorPatchConstantFunction")]

VOut HShader(InputPatch<VOut, 3> patch, uint pointId : SV_OutputControlPointID, uint patchId : SV_PrimitiveID)
{
    VOut output;

    // Set the x for this control point as the output x.
    output.position = patch[pointId].position;

    output.texcoord = patch[pointId].texcoord;
    output.access = patch[pointId].access;
    output.NormalW = patch[pointId].NormalW;
    output.normal = patch[pointId].normal;
    output.depthPosition = patch[pointId].depthPosition;

    return output;
}

//***************************************************//
//                 DOMAIN SHADER                     //
//***************************************************//

struct DOut
{
    float4 position : SV_Position;
	float2 texcoord : TEXCOORD;
	float access : ACCESS;
	
	float3 NormalW : NORMWORLD;
	float4 depthPosition : TEXTURE0;
};

[domain("tri")]

DOut DShader(HOutput input, float3 uvwCoord : SV_DomainLocation, const OutputPatch<VOut, 3> patch)
{
    DOut output;

	float3 vertexPosition;
    float2 texCoords;
    float3 normal;
    float4 worldPosition;

	vertexPosition = uvwCoord.x * patch[0].position + uvwCoord.y * patch[1].position + uvwCoord.z * patch[2].position;

    texCoords = uvwCoord.x * patch[0].texcoord + uvwCoord.y * patch[1].texcoord + uvwCoord.z * patch[2].texcoord;

    normal =  uvwCoord.x * float3(0, 1, 0) + uvwCoord.y * float3(0, 1, 0) + uvwCoord.z * float3(0, 1, 0);
    normal = normalize(normal);

    float vHeight = t_map.SampleLevel(ss, texCoords, 0);
    vertexPosition += float3(0, 1, 0) * (vHeight * 2.0f);

    output.position = mul(float4(vertexPosition, 1.0f), worldMatrix);
    output.position = mul(output.position, viewMatrix);
    output.position = mul(output.position, projectionMatrix);

    output.texcoord = texCoords;

    output.NormalW = mul(normal,(float3x3)worldMatrix);
    output.NormalW = normalize(output.NormalW);

    return output;
}

//***************************************************//
//                 PIXEL SHADER                      //
//***************************************************//

struct POut
{
	float4 Diffuse  : SV_Target0;
	float4 Depth    : SV_Target1;
	float4 Normals  : SV_Target2;
	float4 Lighting : SV_Target3;
};

POut PShader(VOut input)
{
	POut output;

	// Depth
	output.Depth = float4(input.depthPosition.xyz, 1.0f);

	// Normals
	output.Normals = float4(normalize(input.NormalW), 1);

	output.Diffuse = float4(1, 1, 1, 1);
	output.Lighting = float4(lightcol.rgb * input.access, 1.0f);

	output.Lighting = float4(1, 1, 1, 1);

	return output;
}

I've attempted with the pre generated grid, but this came: (The terrain is repeated over and over again, why?)

 

kcxu6f.png

 

Thank you, as always GameDev.

Edited by Migi0027

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Seems no one replied, so I'll try my best.

 

 

The vertices generated on the cpu, do they just represent a plane, or a pre generated grid?

Generate quad on CPU, tesellator stage will create extra triangles, which will result in your terrain.

 

 

How do I decide the height of the displacement mapping, just a constant?

If you're using UNORM or NORM texture, then you need to decide on min/max height. For example 1.0f in texture could mean 255.0f in world space.

If you're using FLOAT texture then just store height directly in the texture.

 

 

How are the normals generated?

It should be possible to calculate them based on data in displacement map, however I haven't done this, so I am unable to help more than this.

 

 

The terrain is repeated over and over again, why?

All your meshes have UV 0.0f to 1.0f, so every terrain ended up reading same texture coordinates.

You need to do do several Draw() calls and use different displacement map for each of them.

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Seems no one replied, so I'll try my best.

 

 

The vertices generated on the cpu, do they just represent a plane, or a pre generated grid?

Generate quad on CPU, tesellator stage will create extra triangles, which will result in your terrain.

 

 

How do I decide the height of the displacement mapping, just a constant?

If you're using UNORM or NORM texture, then you need to decide on min/max height. For example 1.0f in texture could mean 255.0f in world space.

If you're using FLOAT texture then just store height directly in the texture.

 

 

How are the normals generated?

It should be possible to calculate them based on data in displacement map, however I haven't done this, so I am unable to help more than this.

 

 

The terrain is repeated over and over again, why?

All your meshes have UV 0.0f to 1.0f, so every terrain ended up reading same texture coordinates.

You need to do do several Draw() calls and use different displacement map for each of them.

This is most likely the issue.  However, you don't need separate draw calls if you just want to stretch that single displacement map across all of your tiles.  Then you would just use 1.0 / gridsX and 1.0 / gridsY sized pieces for each grid.  Does that make sense?

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Well, a bit closer.

 

Right now I send a quad to the gpu, and then tessellate/displace it from there, but another problem comes, it looks like only half on the quad is being rendered:

 

ao13cm.png

 

The shader practically hasn't changed, only the buffer creation:

Plane_VI plane;

// create the vertex buffer
D3D11_BUFFER_DESC bd;
ZeroMemory(&bd, sizeof(bd));

bd.Usage = D3D11_USAGE_DYNAMIC;
bd.ByteWidth = sizeof(MESH_STRUCT::Dummy) * 4;
bd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
bd.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;
	
dev->CreateBuffer(&bd, NULL, &m_vertexBuffer);

D3D11_MAPPED_SUBRESOURCE ms;
// copy the vertices into the buffer
devcon->Map(m_vertexBuffer, NULL, D3D11_MAP_WRITE_DISCARD, NULL, &ms);    // map the buffer
memcpy(ms.pData, plane.Vertices, sizeof( plane.Vertices	));                 // copy the data
devcon->Unmap(m_vertexBuffer, NULL);

// create the index buffer
bd.Usage = D3D11_USAGE_DYNAMIC;
bd.ByteWidth = sizeof(DWORD) * 6;
bd.BindFlags = D3D11_BIND_INDEX_BUFFER;
bd.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;
bd.MiscFlags = 0;

dev->CreateBuffer(&bd, NULL, &m_indexBuffer);

devcon->Map(m_indexBuffer, NULL, D3D11_MAP_WRITE_DISCARD, NULL, &ms);    // map the buffer
memcpy(ms.pData, plane.Indices, sizeof(plane.Indices));                   // copy the data
devcon->Unmap(m_indexBuffer, NULL);

IndexCount = 6;
m_indexCount = 6;
m_vertexCount = 4;

Definition of Plane_VI:

----HEADER-----
class BASEAPI Plane_VI
{
public:MESH_STRUCT Vertices[4];
public:DWORD Indices[6];

public:
	Plane_VI();
};

----SOURCE-----
Plane_VI::Plane_VI()
{
	Vertices[0] = MESH_STRUCT(-1.0f, 0.0f, -1.0f, D3DXVECTOR3(0.0f, 1.0f, 0.0f), 0.0f, 1.0f, 0, 0, 0);
	Vertices[1] = MESH_STRUCT(1.0f, 0.0f, -1.0f, D3DXVECTOR3(0.0f, 1.0f, 0.0f), 1.0f, 1.0f, 0, 0, 0);
	Vertices[2] = MESH_STRUCT(-1.0f, 0.0f, 1.0f, D3DXVECTOR3(0.0f, 1.0f, 0.0f), 0.0f, 0.0f, 0, 0, 0);
	Vertices[3] = MESH_STRUCT(1.0f, 0.0f, 1.0f, D3DXVECTOR3(0.0f, 1.0f, 0.0f), 1.0f, 0.0f, 0, 0, 0);

	Indices[0] = 3;
	Indices[1] = 1;
	Indices[2] = 2;
	Indices[3] = 2;
	Indices[4] = 1;
	Indices[5] = 0;
};

The primitive topology I'm using (Could this be part of the problem?):

devcon->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_3_CONTROL_POINT_PATCHLIST); // devcon -> Device Context

Now what have I done wrong? happy.png  

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I already suggested a pass-through geometry shader for inspecting values in PIX. If you can't use PIX or something, visualizing manually helps as an alternative. Currently I suspect something wrong with the tex-coords. Pass them along and output them in the pixel-shader as colors (return float4(texcoord.xy, 0, 1);). You should see some red-green-yellow color gradient.

Or bind the displacement map to your pixel shader instead and sample (and output) there, to see if the sampling is the culprit (solid instead of wireframe and without displacement).

Also, show your domain shader.

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PS. The domain shader is at the top of this page, in the shader file smile.png

 

Though I am going to do as suggested, I'm pretty sure that the UV's are fine, as I've used them before, but I might be wrong.

 

Something I forgot to add:

class BASEAPI MESH_STRUCT {
public: 
	FLOAT X, Y, Z; D3DXVECTOR3 Normal; FLOAT U, V; FLOAT tx; FLOAT ty; FLOAT tz; float accessability; D3DXVECTOR4 bWeight; // XYZ:Position, UV: Texture, txtytz: Tangent
//... Not nessesary
};

This should tell you the UV coords.

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Hmmm, tangents, accessability and weights ? Don't see them in your vertex shader input at all. Also: make sure your input layout is ok.

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About that, some of the are used, some are not, but the input layout is correct, and in the correct order, but if you want to see:

 

D3D11_INPUT_ELEMENT_DESC ied[] =
{
{"POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, D3D11_APPEND_ALIGNED_ELEMENT, D3D11_INPUT_PER_VERTEX_DATA, 0},
{"NORMAL", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, D3D11_APPEND_ALIGNED_ELEMENT, D3D11_INPUT_PER_VERTEX_DATA, 0},
{"TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, D3D11_APPEND_ALIGNED_ELEMENT, D3D11_INPUT_PER_VERTEX_DATA, 0},
};

if (dev->CreateInputLayout(ied, 3, VS->GetBufferPointer(), VS->GetBufferSize(), &pLayout) != S_OK)
...

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Yeah, looks fine (though I for one wouldn't use a float4 for the normal in the shader). I assume the stride when binding the buffer is ok, too.

Try the other approaches.

You wouldn't mind posting that displacement texture, please ?

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Sure! wink.png

 

28lz05h.jpg

 

PS. I know, it's quite small, but it's fine for now.

Edited by Migi0027

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