Jump to content

  • Log In with Google      Sign In   
  • Create Account

[D3D10, SSAO] Need help with finishing SSAO implementation


Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.

  • You cannot reply to this topic
1 reply to this topic

#1 rychu_elektryk   Members   -  Reputation: 126

Like
0Likes
Like

Posted 06 February 2012 - 08:27 AM

Hi Everyone!

I'm seeking some help in implementing SSAO. I'm basing on John Chapman's tutorial -> http://www.john-chap...ontent.php?id=8 . Well the tutorial seems quite simple, and I think I've implemented each part of it correctly. Unfortunatelly results shows that somethings deffinitelly is wrong. If You could help, I'd appreciate that. So, here it goes:

HLSL code (shader 4.0 Dx10)

First part is storing:
linear normalized depth
viewspace normals
colour

struct VS_I_POS_TEX
{
float4 position	 : POSITION;
	float2 textureCoordinates  : TEXCOORD;
};
//-------------------------------------------------------------------------
struct VS_O_POS_TEX_EYE
{
float4 position	: SV_POSITION;
	float2 textureCoordinates  : TEXCOORD0;
float3 eyePosition	   : TEXCOORD1;
};
//-------------------------------------------------------------------------
struct PS_I_POS_TEX_EYE
{
float4 position	: SV_POSITION;
	float2 textureCoordinates  : TEXCOORD0;
float3 eyePosition	   : TEXCOORD1;
};
//-------------------------------------------------------------------------
struct PS_O_COLOR_NORM_DEPTH
{
	float4  color		: SV_Target0;
	float4  normal	   : SV_Target1;
	float  normalizedLinearDepth : SV_Target2;
};

VS_O_POS_TEX_EYE VS_MRTRendering(VS_I_POS_TEX vsInput)
{
VS_O_POS_TEX_EYE vsOutput = (VS_O_POS_TEX_EYE)0;
  
	vsOutput.position	= mul(vsInput.position, matrix_view);
vsOutput.eyePosition  = vsOutput.position.xyz;
vsOutput.position	= mul(vsOutput.position, matrix_projection);
vsOutput.textureCoordinates = vsInput.textureCoordinates;
	
	return vsOutput;
}
//-------------------------------------------------------------------------
PS_O_COLOR_NORM_DEPTH PS_MRTRendering(PS_I_POS_TEX_EYE psInput)
{  
	PS_O_COLOR_NORM_DEPTH psOutput = (PS_O_COLOR_NORM_DEPTH)0;
  
if(!disableTextures)  psOutput.color = texture_diffuse.Sample(Sampler_anisotropic, psInput.textureCoordinates);
else	 psOutput.color = float4(1.0f, 1.0f, 1.0f, 1.0f);

	psOutput.normal.xyz  = normalize(cross(ddx(psInput.eyePosition.xyz), ddy(psInput.eyePosition.xyz)));
	psOutput.normalizedLinearDepth  = psInput.eyePosition.z / farClip;
  
	return psOutput;
}


And the second part is computing occlusion

struct VS_I_POS_TEX_CORID
{
float3  position	: POSITION;
	float2  textureCoordinates : TEXCOORD;
float cornerId   : CORNERID;
};
struct VS_O_POS_TEX_CORID_VSRAY
{
float4  position_SS	 : SV_POSITION;
float2  textureCoordinates   : TEXCOORD0;
float cornerId	 : CORNERID;
float3  frustumPointCoordinateVS : TEXCOORD1;
};
VS_O_POS_TEX_CORID_VSRAY VS_RenderOcclusion(VS_I_POS_TEX_CORID vsInput)
{
VS_O_POS_TEX_CORID_VSRAY vsOutput = (VS_O_POS_TEX_CORID_VSRAY)0;

vsOutput.position_SS = float4(vsInput.position, 1.0f);
vsOutput.textureCoordinates = vsInput.textureCoordinates.xy;
vsOutput.frustumPointCoordinateVS = aFrustumCornerPosition_VS[vsInput.cornerId];
	return vsOutput;
}
//-------------------------------------------------------------------------
float PS_RenderOcclusion(VS_O_POS_TEX_CORID_VSRAY psInput) : SV_Target
{
float3 viewRay = float3(psInput.frustumPointCoordinateVS.xy, farClip);

float3 origin = viewRay * (float)texture_linearDepth.Sample(Sampler_point, psInput.textureCoordinates);

//I've tested it, and it seems reconstruction works correctly.
//Here's how I tested it:
//I took viewRay.xy and muliplied it by projection matrix, and then divided by w component
//Then I've done some scaling and compared it to the psInput.position.xy
//They match so this part looks correct for me


float3 normal = texture_normals.Sample(Sampler_point, psInput.textureCoordinates).xyz;

normal = normalize(normal);

float3 noiseSample = float3(texture_noiseSamples.Sample(Sampler_point, psInput.textureCoordinates * noiseScale).xy, 0.0f) * 2.0f - 1.0f;

float3 tangent = normalize(noiseSample - normal * dot(noiseSample, normal));

float3 bitangent = cross(normal, tangent);

float3x3 tbn = float3x3(tangent, bitangent, normal);
tbn = transpose(tbn);

float occlusion = 0.0f;

int samplesCount = 16;
float radius = 0.5f;

for(int i = 0; i < samplesCount; ++i)
{
  float3 sample = mul(aRandomSamples[i], tbn);

  sample = sample * radius + origin;
  
  float4 offset = float4(sample, 1.0);

  offset = mul(offset, matrix_projection);
  offset.xy /= offset.w;
  offset.xy = offset.xy * 0.5 + 0.5;
  
  float sample_depth = (float)texture_linearDepth.Sample(Sampler_point, offset.xy);

  occlusion += (sample_depth <= sample.z ? 1.0 : 0.0);
}

occlusion = 1.0 - (occlusion / samplesCount);

return occlusion;
}


That's mainly it. Here's the results(fulscreen quad with only occlusion texture)

Posted Image

It's a sponza model, and the camera is looking from the flor to the sky. Only looking to the sky shows some results.


Well, what do You think of it? I have no idea what could be possibly wrong with this implementation.



[color=#fafafa !important][/color]Posted Image



Sponsor:

#2 rychu_elektryk   Members   -  Reputation: 126

Like
0Likes
Like

Posted 06 February 2012 - 12:51 PM

Ok. I found one mistake.

On the line:
float sample_depth = (float)texture_linearDepth.Sample(Sampler_point, offset.xy);


I forgot to multiply by farClip value. After correction the output is far from being ok.

Actual output:
Posted Image


[color=#fafafa !important][/color]Posted Image






Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.



PARTNERS