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DX11 - SSAO


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#1 肉Mode   Crossbones+   -  Reputation: 1787

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Posted 17 July 2013 - 03:50 PM

I'm so terribly sorry to re-re-re open this one, but I never fully succeeded at this one, SSAO. unsure.png

 

SSAO Shader:

Texture2D t_depthmap : register(t0);
Texture2D t_normalmap : register(t1);
Texture2D t_random : register(t2);
SamplerState ss;

cbuffer SSAOBuffer : register(c0)
{
	float g_scale;
	float g_bias;
	float g_sample_rad;
	float g_intensity;
	float ssaoIterations;
	float3 pppspace;

	matrix view;
};

struct VS_Output
{  
	float4 Pos : SV_POSITION;              
	float2 Tex : TEXCOORD0;
};
 
VS_Output VShader(uint id : SV_VertexID)
{
	VS_Output Output;
	Output.Tex = float2((id << 1) & 2, id & 2);
	Output.Pos = float4(Output.Tex * float2(2,-2) + float2(-1,1), 0, 1);
	return Output;
}

// Helper for modifying the saturation of a color.
float4 AdjustSaturation(float4 color, float saturation)
{
	// The constants 0.3, 0.59, and 0.11 are chosen because the
	// human eye is more sensitive to green light, and less to blue.
	float grey = dot(color, float3(0.3, 0.59, 0.11));

	return lerp(grey, color, saturation);
}

// Ambient Occlusion Stuff --------------------------------------------------

float3 getPosition(in float2 uv)
{
	return t_depthmap.Sample(ss, uv).xyz;
}

float3 getNormal(in float2 uv)
{
	return normalize(t_normalmap.Sample(ss, uv).xyz * 2.0f - 1.0f);
}

float2 getRandom(in float2 uv)
{
	//return normalize(t_random.Sample(ss, uv ).xy * 2.0f - 1.0f); // ~100FPS
	return normalize(t_random.Sample(ss, float2(600, 800) * uv / float2(60, 60)).xy * 2.0f - 1.0f);
}

float doAmbientOcclusion(in float2 tcoord,in float2 uv, in float3 p, in float3 cnorm)
{
	float3 diff = getPosition(tcoord + uv) - p;
	const float3 v = normalize(diff);
	const float d = length(diff)*g_scale;
	return max(0.0,dot(cnorm,v)-g_bias)*(1.0/(1.0+d))*g_intensity;
}

// End

float4 PShader(VS_Output input) : SV_TARGET
{
	// ADD SSAO ---------------------------------------------------------------
	const float2 vec[4] = {float2(1,0),float2(-1,0),
				float2(0,1),float2(0,-1)};

	float3 p = getPosition(input.Tex);
	float3 n = getNormal(input.Tex);
	float2 rand = getRandom(input.Tex);

	float ao = 0.0f;
	float rad = g_sample_rad/p.z; // g_s_r

	//**SSAO Calculation**//
	int iterations = 4;
	for (int j = 0; j < iterations; ++j)
	{
	  float2 coord1 = reflect(vec[j], rand)*rad;
	  float2 coord2 = float2(coord1.x*0.707 - coord1.y*0.707,
				  coord1.x*0.707 + coord1.y*0.707);
	  
	  ao += doAmbientOcclusion(input.Tex, coord1*0.25, p, n);
	  ao += doAmbientOcclusion(input.Tex, coord2*0.5, p, n);
	  ao += doAmbientOcclusion(input.Tex, coord1*0.75, p, n);
	  ao += doAmbientOcclusion(input.Tex, coord2, p, n);
	}
	ao /= (float)iterations*4.0;

	ao = saturate(ao);

	return float4(ao, ao, ao, 1.0f);
}

How I write my depth map to the ssao:

VS
output.depth = output.position.z / output.position.w;
PS
float depth = input.depth;
output.Depth = float4(depth, depth, depth, 1);

How i write my normal map to the ssao:

VS -- I think this is wrong
output.NormalW = mul(mul(worldMatrix, viewMatrix), float4(normal.xyz,0) );
PS
output.Normals = float4(input.NormalW, 1);

Render Result:

 

2ztay6g.png

 

Ehh.

 

Again, I'm so sorry for re-posting this, it's just, i really want this feature completed (well, working at least).

 

Thank You, like always...


Hi! Cuboid Zone
The Rule: Be polite, be professional, but have a plan to kill everyone you meet, ohh, AND STEAL ALL ZE TRIANGLES FROM ZHEM!

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#2 Adam_42   Crossbones+   -  Reputation: 2512

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Posted 17 July 2013 - 05:51 PM

Why not use an existing implementation like the one from nvidia at https://developer.nvidia.com/nvidia-graphics-sdk-11-direct3d ?

 

Looking at your shader the first thing that strikes me is that your depth texture has more than one channel, where they are usually single channel.



#3 肉Mode   Crossbones+   -  Reputation: 1787

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Posted 18 July 2013 - 01:30 AM

So how would the depth shader be written correctly to the SSAO shader?

 

Thank you for your interest by the way, appreciate it!


Hi! Cuboid Zone
The Rule: Be polite, be professional, but have a plan to kill everyone you meet, ohh, AND STEAL ALL ZE TRIANGLES FROM ZHEM!

#4 belfegor   Crossbones+   -  Reputation: 2623

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Posted 18 July 2013 - 04:24 AM

I think that that ssao shader needs view space position (whole three components x,y and z), as i can see you store normals that way, although:

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

this mul order is right if shader packs matrices as column major, i don't know dx11  shader systems so i am not sure, but in dx9 i can force row major with this statement:

#pragma pack_matrix(row_major)

beacuse it matches my system in cpp code and i always mul vectors with matrices this way:

result = mul( vec, matrix );

Edited by belfegor, 18 July 2013 - 04:27 AM.


#5 肉Mode   Crossbones+   -  Reputation: 1787

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Posted 18 July 2013 - 10:59 AM

Ok, it is a bit better now in the sense that it doesn't just become randomly black: (SSAO Map)

 

2vjsx8h.png

 

 

But this isn't right yet, well I don't think it is, I mean look at the left of the cube, where the left side is rendered, it's black, why?

 

Ohh, and belfegor, about the matrices, you were right!

 

How I write my depth map to the ssao:

VS:

output.position = mul(position, worldMatrix);
output.position = mul(output.position, viewMatrix);
output.position = mul(output.position, projectionMatrix);

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

// Store the position value in a second input value for depth value calculations.
output.depthPosition = output.position;
PS:

// Depth
float depth = 1.0f - (input.depthPosition.z / input.depthPosition.w);
output.Depth = float4(depth, depth, depth, 1.0f);

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

Now, is this the correct way to map the depth and the normal maps?


Hi! Cuboid Zone
The Rule: Be polite, be professional, but have a plan to kill everyone you meet, ohh, AND STEAL ALL ZE TRIANGLES FROM ZHEM!

#6 belfegor   Crossbones+   -  Reputation: 2623

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Posted 18 July 2013 - 11:18 AM

I said output view space position, so it is like this:

VS
output.depthPosition.xyz = mul(float4(position.xyz,1), mul(worldMatrix, viewMatrix)).xyz;
PS
output.Depth = float4(input.depthPosition.xyz, 1.0f);

although you must have proper render target (or "view" whatever they call it in dx11) format that can hold at least 3 floating point components.

 

And why do you invert your normals now?

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

Then when you fix those issues, play with ssao "sampling radius" to match your world scale (in case you don't get expected results).


Edited by belfegor, 18 July 2013 - 11:25 AM.


#7 肉Mode   Crossbones+   -  Reputation: 1787

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Posted 18 July 2013 - 11:46 AM

Sorry about the normals, just testing, and forgot it there...

 

The result, is this correct?

 

2gy57yw.png


Hi! Cuboid Zone
The Rule: Be polite, be professional, but have a plan to kill everyone you meet, ohh, AND STEAL ALL ZE TRIANGLES FROM ZHEM!

#8 belfegor   Crossbones+   -  Reputation: 2623

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Posted 18 July 2013 - 12:01 PM

I would say no. Try decreasing "g_sample_rad" and invert result like this:

ao = 1 - saturate(ao);


#9 肉Mode   Crossbones+   -  Reputation: 1787

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Posted 18 July 2013 - 12:16 PM

Now looks like this, look at the variables in the upper left corner:

 

6eq07n.png


Hi! Cuboid Zone
The Rule: Be polite, be professional, but have a plan to kill everyone you meet, ohh, AND STEAL ALL ZE TRIANGLES FROM ZHEM!

#10 belfegor   Crossbones+   -  Reputation: 2623

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Posted 18 July 2013 - 12:30 PM

Let me try this one with my renderer and i get back to you. smile.png

 

EDIT: Here is it (on and off). All parameters are same as yours except radius which i set to 0.1f (10cm in my world) since it feels more natural for me.

 

oma-2013-07-18-20-47-50-.jpg

oma-2013-07-18-20-47-53-.jpg


Edited by belfegor, 18 July 2013 - 12:55 PM.


#11 肉Mode   Crossbones+   -  Reputation: 1787

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Posted 18 July 2013 - 01:20 PM

So are my values correct, taking away the radius?


Hi! Cuboid Zone
The Rule: Be polite, be professional, but have a plan to kill everyone you meet, ohh, AND STEAL ALL ZE TRIANGLES FROM ZHEM!

#12 肉Mode   Crossbones+   -  Reputation: 1787

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Posted 18 July 2013 - 01:26 PM

Using radius of 0.1:

 

2cia4ps.png

 

I have absolutely no idea of where i snapped these values. laugh.png


Hi! Cuboid Zone
The Rule: Be polite, be professional, but have a plan to kill everyone you meet, ohh, AND STEAL ALL ZE TRIANGLES FROM ZHEM!

#13 belfegor   Crossbones+   -  Reputation: 2623

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Posted 18 July 2013 - 01:46 PM

I played a little more with this and done some changes that look better then before (at least for me), so you might want to try:

1. I have normalized view space normals in texture, and i don't get why do we need to scale-bias here? Also, this fixes some ugly artifacts.

float3 getNormal(in float2 uv)
{
    //return normalize(tex2D(gbNormal_samp, uv).xyz * 2.0f - 1.0f);
    return tex2D(gbNormal_samp, uv).xyz;
}

So you might need to change your gbuffer normal to be normalized also

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

 

2. I had getRandom before which looks nice for me:

float3 getRandom(in float2 uv)
{
    return tex2D(rand_samp, uv * ScreenParams.xy / 4.0f).xyz * 2.0f - 1.0f;
}

3. Setting scale to 0 looks better for me, so i can even remove some calculations:

float doAmbientOcclusion(in float2 tcoord,in float2 uv, in float3 p, in float3 cnorm)
{
    float g_scale = SSAO_params.x;
    float g_bias = SSAO_params.y;
    float g_intensity = SSAO_params.z;

    float3 diff = getPosition(tcoord + uv) - p;
    const float3 v = normalize(diff);
    //const float d = length(diff)*g_scale;
    return max(0.0,dot(cnorm,v)-g_bias)*g_intensity;//(1.0/(1.0+d))*g_intensity;
}

4. I get strange "haloing" artifacts on screen corners, so i set position and normal texture UV addressing mode to mirror and it seems that fixes that issue.

 

5. Changed radius to 0.15 and intensity to ~2.5


Edited by belfegor, 18 July 2013 - 01:50 PM.


#14 肉Mode   Crossbones+   -  Reputation: 1787

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Posted 18 July 2013 - 02:08 PM

The reason for the false occlusions at the corners is simply because there is nothing in the scene there,

 

2db9ok1.png

 

But as you see in the bottom, when I go too close to the mesh, these false occlusions start to appear, and when really close, they're everywhere!


Hi! Cuboid Zone
The Rule: Be polite, be professional, but have a plan to kill everyone you meet, ohh, AND STEAL ALL ZE TRIANGLES FROM ZHEM!




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