Original Post
I have to questions for you guys .. 1. What are the optimizations that I can make to my bloom shader? (see code below) 2. How do I properly reduce the number of samples taken without losing quality? I remember reading something somewhere that said I should be able to calculate values in between texels and adjust the weights appropriately, but I dont remember what or where it was. What is the algorithm used for this?
//Constants
static const int cKernelSize = 13;
static const float fBrightThreshold = 0.6f;
static const float fBloomScale = 1.5f;
//Extern parameters
uniform extern texture Tex;
uniform extern texture OriginalTex;
uniform extern unsigned int unWidth;
uniform extern unsigned int unHeight;
//Offsets
uniform extern float2 BlurOffsetsH[cKernelSize];
uniform extern float2 BlurOffsetsV[cKernelSize];
uniform extern float2 ScaleOffsets[16];
//Samplers
sampler2D g_SampTex = sampler_state
{
Texture = <Tex>;
AddressU = Clamp;
AddressV = Clamp;
MinFilter = Point;
MagFilter = Linear;
MipFilter = None;
};
sampler2D g_SampOriginalTex = sampler_state
{
Texture = <OriginalTex>;
AddressU = Clamp;
AddressV = Clamp;
MinFilter = Linear;
MagFilter = Linear;
MipFilter = None;
};
//Blur Weights
static const float BlurWeights[cKernelSize] =
{
1.0f / 4096.0f,
12.0f / 4096.0f,
66.0f / 4096.0f,
220.0f / 4096.0f,
495.0f / 4096.0f,
792.0f / 4096.0f,
924.0f / 4096.0f,
792.0f / 4096.0f,
495.0f / 4096.0f,
220.0f / 4096.0f,
66.0f / 4096.0f,
12.0f / 4096.0f,
1.0f / 4096.0f,
};
//Brightpass
float4 DownSample4xBrightPass(float2 uv : TEXCOORD1 ) : COLOR0
{
float4 Color = 0;
for (int i = 0; i < 16; i++)
{
Color += tex2D( g_SampTex, uv + ScaleOffsets.xy ) - fBrightThreshold;
}
return Color / 16;
}
//Horizontal Blur
float4 HorizontalBlurPS(float2 uv : TEXCOORD1 ) : COLOR0
{
float4 Color = 0;
for (int i = 0; i < cKernelSize; i++)
{
Color += tex2D( g_SampTex, uv + BlurOffsetsH.xy ) * BlurWeights;
}
return Color * fBloomScale;
}
//Vertical Blur
float4 VerticalBlurPS(float2 uv : TEXCOORD1 ) : COLOR0
{
float4 Color = 0;
for (int i = 0; i < cKernelSize; i++)
{
Color += tex2D( g_SampTex, uv + BlurOffsetsV.xy ) * BlurWeights;
}
return Color * fBloomScale;
}
//Upscale and blend
float4 UpSample4xBlend(float2 uv : TEXCOORD0 ) : COLOR0
{
return tex2D( g_SampTex, uv) * 0.8 + tex2D( g_SampOriginalTex, uv);
}
technique TBloom
{
pass p0
{
VertexShader = null;
PixelShader = compile ps_2_0 DownSample4xBrightPass();
}
pass p1
{
VertexShader = null;
PixelShader = compile ps_2_0 HorizontalBlurPS();
}
pass p2
{
VertexShader = null;
PixelShader = compile ps_2_0 VerticalBlurPS();
}
pass p3
{
VertexShader = null;
PixelShader = compile ps_2_0 UpSample4xBlend();
}
}
