• Advertisement
Sign in to follow this  

[D3D10, SSAO] Need help with finishing SSAO implementation

This topic is 2173 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi Everyone!

I'm seeking some help in implementing SSAO. I'm basing on John Chapman's tutorial -> [url="http://www.john-chapman.net/content.php?id=8"]http://www.john-chap...ontent.php?id=8[/url] . 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

[source]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;
}[/source]

And the second part is computing occlusion

[source]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;
}[/source]

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

[img]http://i.imm.io/fZTs.jpeg[/img]

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

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


[left][color=#fafafa !important][/color][img]http://www.google.com/uds/css/small-logo.png[/img][/left]

Share this post


Link to post
Share on other sites
Advertisement
Ok. I found one mistake.

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

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

Actual output:
[img]http://i.imm.io/g10G.jpeg[/img][left]
[color=#fafafa !important][size=4][/size][/color][img]http://www.google.com/uds/css/small-logo.png[/img][/left]

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement