Class CustomPassUtils

A set of custom pass utility function to help you build your effects

Inheritance

object

CustomPassUtils

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: UnityEngine.Rendering.HighDefinition

Assembly: Unity.RenderPipelines.HighDefinition.Runtime.dll

Syntax

public static class CustomPassUtils

Fields

fullScreenScaleBias

Fullscreen scale and bias values, it is the default for functions that have scale and bias overloads.

Declaration

public static Vector4 fullScreenScaleBias

Field Value

Type	Description
Vector4	x: scaleX, y: scaleY, z: biasX, w: biasY

Methods

Copy(in CustomPassContext, RTHandle, RTHandle, int, int)

Copy an RTHandle content to another

Declaration

public static void Copy(in CustomPassContext ctx, RTHandle source, RTHandle destination, int sourceMip = 0, int destMip = 0)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the copy
RTHandle	destination	Destination buffer of the copy
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.

Copy(in CustomPassContext, RTHandle, RTHandle, Vector4, Vector4, int, int)

Copy a region of an RTHandle to another

Declaration

public static void Copy(in CustomPassContext ctx, RTHandle source, RTHandle destination, Vector4 sourceScaleBias, Vector4 destScaleBias, int sourceMip = 0, int destMip = 0)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the copy
RTHandle	destination	Destination buffer of the copy
Vector4	sourceScaleBias	Scale and bias to apply when sampling the source buffer
Vector4	destScaleBias	Scale and bias to apply when writing into the destination buffer.
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.

DownSample(in CustomPassContext, RTHandle, RTHandle, int, int)

Convert the source buffer to an half resolution buffer and output it to the destination buffer.

Declaration

public static void DownSample(in CustomPassContext ctx, RTHandle source, RTHandle destination, int sourceMip = 0, int destMip = 0)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the downsample
RTHandle	destination	Destination buffer of the downsample
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.

DownSample(in CustomPassContext, RTHandle, RTHandle, Vector4, Vector4, int, int)

Convert the source buffer to an half resolution buffer and output it to the destination buffer.

Declaration

public static void DownSample(in CustomPassContext ctx, RTHandle source, RTHandle destination, Vector4 sourceScaleBias, Vector4 destScaleBias, int sourceMip = 0, int destMip = 0)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the downsample
RTHandle	destination	Destination buffer of the downsample
Vector4	sourceScaleBias	Scale and bias to apply when sampling the source buffer
Vector4	destScaleBias	Scale and bias to apply when writing into the destination buffer. It's scale is relative to the destination buffer, so if you want an half res downsampling into a fullres buffer you need to specify a scale of 0.5;0,5. If your buffer is already half res Then 1;1 scale works.
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.

DrawRenderers(in CustomPassContext, LayerMask, RenderQueueType, Material, int, RenderStateBlock, SortingCriteria)

Simpler version of ScriptableRenderContext.DrawRenderers to draw HDRP materials.

Declaration

public static void DrawRenderers(in CustomPassContext ctx, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, Material overrideMaterial = null, int overrideMaterialIndex = 0, RenderStateBlock overrideRenderState = default, SortingCriteria sorting = SortingCriteria.SortingLayer | SortingCriteria.RenderQueue | SortingCriteria.OptimizeStateChanges | SortingCriteria.CanvasOrder)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
Material	overrideMaterial	Optional material that will be used to render the objects.
int	overrideMaterialIndex	Pass index to use for the override material.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.
SortingCriteria	sorting	How the objects are sorted before being rendered.

DrawRenderers(in CustomPassContext, ShaderTagId[], LayerMask, RenderQueueType, Material, int, RenderStateBlock, SortingCriteria)

Simpler version of ScriptableRenderContext.DrawRenderers to draw HDRP materials.

Declaration

public static void DrawRenderers(in CustomPassContext ctx, ShaderTagId[] shaderTags, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, Material overrideMaterial = null, int overrideMaterialIndex = 0, RenderStateBlock overrideRenderState = default, SortingCriteria sorting = SortingCriteria.SortingLayer | SortingCriteria.RenderQueue | SortingCriteria.OptimizeStateChanges | SortingCriteria.CanvasOrder)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
ShaderTagId[]	shaderTags	List of shader tags to use when rendering the objects. This acts as a filter to select which objects to render and as selector to know which pass to render.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
Material	overrideMaterial	Optional material that will be used to render the objects.
int	overrideMaterialIndex	Pass index to use for the override material.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.
SortingCriteria	sorting	How the objects are sorted before being rendered.

GaussianBlur(in CustomPassContext, RTHandle, RTHandle, RTHandle, int, float, int, int, bool)

Gaussian Blur pass.

Declaration

public static void GaussianBlur(in CustomPassContext ctx, RTHandle source, RTHandle destination, RTHandle tempTarget, int sampleCount = 9, float radius = 5, int sourceMip = 0, int destMip = 0, bool downSample = true)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the gaussian blur.
RTHandle	destination	Destination buffer of the gaussian blur.
RTHandle	tempTarget	Temporary render target to provide used internally to swap the result between blur passes. Can be half res if downsample is true.
int	sampleCount	Number of samples to use for the gaussian blur. A high number will impact performances.
float	radius	Radius in pixel of the gaussian blur.
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.
bool	downSample	If true, will execute a downsample pass before the blur. It increases the performances of the blur.

GaussianBlur(in CustomPassContext, RTHandle, RTHandle, RTHandle, Vector4, Vector4, int, float, int, int, bool)

Gaussian Blur pass.

Declaration

public static void GaussianBlur(in CustomPassContext ctx, RTHandle source, RTHandle destination, RTHandle tempTarget, Vector4 sourceScaleBias, Vector4 destScaleBias, int sampleCount = 9, float radius = 5, int sourceMip = 0, int destMip = 0, bool downSample = true)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the gaussian blur.
RTHandle	destination	Destination buffer of the gaussian blur.
RTHandle	tempTarget	Temporary render target to provide used internally to swap the result between blur passes. Can be half res if downsample is true.
Vector4	sourceScaleBias	Scale and bias to apply when sampling the source buffer.
Vector4	destScaleBias	Scale and bias to apply when writing into the destination buffer.
int	sampleCount	Number of samples to use for the gaussian blur. A high number will impact performances.
float	radius	Radius in pixel of the gaussian blur.
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.
bool	downSample	If true, will execute a downsample pass before the blur. It increases the performances of the blur.

GetRenderQueueRangeFromRenderQueueType(RenderQueueType)

Convert a Custom Pass render queue type to a RenderQueueRange that can be used in DrawRenderers

Declaration

public static RenderQueueRange GetRenderQueueRangeFromRenderQueueType(CustomPass.RenderQueueType type)

Parameters

Type	Name	Description
CustomPass.RenderQueueType	type	The type of render queue

Returns

Type	Description
RenderQueueRange	The converted render queue range

HorizontalGaussianBlur(in CustomPassContext, RTHandle, RTHandle, int, float, int, int)

Horizontal gaussian blur pass.

Declaration

public static void HorizontalGaussianBlur(in CustomPassContext ctx, RTHandle source, RTHandle destination, int sampleCount = 8, float radius = 5, int sourceMip = 0, int destMip = 0)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the gaussian blur.
RTHandle	destination	Destination buffer of the gaussian blur.
int	sampleCount	Number of samples to use for the gaussian blur. A high number will impact performances.
float	radius	Radius in pixel of the gaussian blur.
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.

HorizontalGaussianBlur(in CustomPassContext, RTHandle, RTHandle, Vector4, Vector4, int, float, int, int)

Horizontal gaussian blur pass.

Declaration

public static void HorizontalGaussianBlur(in CustomPassContext ctx, RTHandle source, RTHandle destination, Vector4 sourceScaleBias, Vector4 destScaleBias, int sampleCount = 8, float radius = 5, int sourceMip = 0, int destMip = 0)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the gaussian blur.
RTHandle	destination	Destination buffer of the gaussian blur.
Vector4	sourceScaleBias	Scale and bias to apply when sampling the source buffer.
Vector4	destScaleBias	Scale and bias to apply when writing into the destination buffer.
int	sampleCount	Number of samples to use for the gaussian blur. A high number will impact performances.
float	radius	Radius in pixel of the gaussian blur.
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.

RenderDepthFromCamera(in CustomPassContext, Camera, LayerMask, RenderQueueType, RenderStateBlock)

Render eye space depth of objects from the view point of a camera into the color buffer.

Declaration

public static void RenderDepthFromCamera(in CustomPassContext ctx, Camera view, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderDepthFromCamera(in CustomPassContext, Camera, RenderTexture, ClearFlag, LayerMask, RenderQueueType, RenderStateBlock)

Render eye space depth of objects from the view point of a camera into the color and depth buffers.

Declaration

public static void RenderDepthFromCamera(in CustomPassContext ctx, Camera view, RenderTexture targetRenderTexture, ClearFlag clearFlag, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
RenderTexture	targetRenderTexture	The render target that will be bound before rendering the objects.
ClearFlag	clearFlag	The type of clear to do before binding the render targets.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderDepthFromCamera(in CustomPassContext, Camera, RTHandle, RTHandle, ClearFlag, LayerMask, RenderQueueType, RenderStateBlock)

Render eye space depth of objects from the view point of a camera into the color and depth buffers.

Declaration

public static void RenderDepthFromCamera(in CustomPassContext ctx, Camera view, RTHandle targetColor, RTHandle targetDepth, ClearFlag clearFlag, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
RTHandle	targetColor	The render target that will be bound to the color buffer before rendering
RTHandle	targetDepth	The render target that will be bound to the depth buffer before rendering
ClearFlag	clearFlag	The type of clear to do before binding the render targets.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderFromCamera(in CustomPassContext, Camera, LayerMask, RenderQueueType, Material, int, RenderStateBlock)

Render a list of objects from another camera point of view.

Declaration

public static void RenderFromCamera(in CustomPassContext ctx, Camera view, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, Material overrideMaterial = null, int overrideMaterialIndex = 0, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
Material	overrideMaterial	Optional material that will be used to render the objects.
int	overrideMaterialIndex	Pass index to use for the override material.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderFromCamera(in CustomPassContext, Camera, RenderTexture, ClearFlag, LayerMask, RenderQueueType, Material, int, RenderStateBlock)

Render a list of objects from another camera point of view.

Declaration

public static void RenderFromCamera(in CustomPassContext ctx, Camera view, RenderTexture targetRenderTexture, ClearFlag clearFlag, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, Material overrideMaterial = null, int overrideMaterialIndex = 0, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
RenderTexture	targetRenderTexture	The render target that will be bound before rendering the objects.
ClearFlag	clearFlag	The type of clear to do before binding the render targets.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
Material	overrideMaterial	Optional material that will be used to render the objects.
int	overrideMaterialIndex	Pass index to use for the override material.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderFromCamera(in CustomPassContext, Camera, RTHandle, RTHandle, ClearFlag, LayerMask, RenderQueueType, Material, int, RenderStateBlock)

Render a list of objects from another camera point of view.

Declaration

public static void RenderFromCamera(in CustomPassContext ctx, Camera view, RTHandle targetColor, RTHandle targetDepth, ClearFlag clearFlag, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, Material overrideMaterial = null, int overrideMaterialIndex = 0, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
RTHandle	targetColor	The render target that will be bound to the color buffer before rendering
RTHandle	targetDepth	The render target that will be bound to the depth buffer before rendering
ClearFlag	clearFlag	The type of clear to do before binding the render targets.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
Material	overrideMaterial	Optional material that will be used to render the objects.
int	overrideMaterialIndex	Pass index to use for the override material.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderNormalFromCamera(in CustomPassContext, Camera, LayerMask, RenderQueueType, RenderStateBlock)

Render world space normal of objects from the view point of a camera into the color buffer.

Declaration

public static void RenderNormalFromCamera(in CustomPassContext ctx, Camera view, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderNormalFromCamera(in CustomPassContext, Camera, RenderTexture, ClearFlag, LayerMask, RenderQueueType, RenderStateBlock)

Render world space normal of objects from the view point of a camera into the color buffer.

Declaration

public static void RenderNormalFromCamera(in CustomPassContext ctx, Camera view, RenderTexture targetRenderTexture, ClearFlag clearFlag, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
RenderTexture	targetRenderTexture	The render target that will be bound before rendering the objects.
ClearFlag	clearFlag	The type of clear to do before binding the render targets.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderNormalFromCamera(in CustomPassContext, Camera, RTHandle, RTHandle, ClearFlag, LayerMask, RenderQueueType, RenderStateBlock)

Render world space normal of objects from the view point of a camera into the color buffer.

Declaration

public static void RenderNormalFromCamera(in CustomPassContext ctx, Camera view, RTHandle targetColor, RTHandle targetDepth, ClearFlag clearFlag, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
RTHandle	targetColor	The render target that will be bound to the color buffer before rendering
RTHandle	targetDepth	The render target that will be bound to the depth buffer before rendering
ClearFlag	clearFlag	The type of clear to do before binding the render targets.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderTangentFromCamera(in CustomPassContext, Camera, LayerMask, RenderQueueType, RenderStateBlock)

Render world space tangent of objects from the view point of a camera into the color buffer.

Declaration

public static void RenderTangentFromCamera(in CustomPassContext ctx, Camera view, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderTangentFromCamera(in CustomPassContext, Camera, RenderTexture, ClearFlag, LayerMask, RenderQueueType, RenderStateBlock)

Render world space tangent of objects from the view point of a camera into the color buffer

Declaration

public static void RenderTangentFromCamera(in CustomPassContext ctx, Camera view, RenderTexture targetRenderTexture, ClearFlag clearFlag, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
RenderTexture	targetRenderTexture	The render target that will be bound before rendering the objects.
ClearFlag	clearFlag	The type of clear to do before binding the render targets.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

RenderTangentFromCamera(in CustomPassContext, Camera, RTHandle, RTHandle, ClearFlag, LayerMask, RenderQueueType, RenderStateBlock)

Render world space tangent of objects from the view point of a camera into the color buffer

Declaration

public static void RenderTangentFromCamera(in CustomPassContext ctx, Camera view, RTHandle targetColor, RTHandle targetDepth, ClearFlag clearFlag, LayerMask layerMask, CustomPass.RenderQueueType renderQueueFilter = RenderQueueType.All, RenderStateBlock overrideRenderState = default)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
Camera	view	The camera from where you want the objects to be rendered.
RTHandle	targetColor	The render target that will be bound to the color buffer before rendering
RTHandle	targetDepth	The render target that will be bound to the depth buffer before rendering
ClearFlag	clearFlag	The type of clear to do before binding the render targets.
LayerMask	layerMask	LayerMask to filter the objects to render.
CustomPass.RenderQueueType	renderQueueFilter	Render Queue to filter the type of objects you want to render.
RenderStateBlock	overrideRenderState	The render states to override when rendering the objects.

VerticalGaussianBlur(in CustomPassContext, RTHandle, RTHandle, int, float, int, int)

Vertical gaussian blur pass

Declaration

public static void VerticalGaussianBlur(in CustomPassContext ctx, RTHandle source, RTHandle destination, int sampleCount = 8, float radius = 5, int sourceMip = 0, int destMip = 0)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the gaussian blur.
RTHandle	destination	Destination buffer of the gaussian blur.
int	sampleCount	Number of samples to use for the gaussian blur. A high number will impact performances.
float	radius	Radius in pixel of the gaussian blur.
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.

VerticalGaussianBlur(in CustomPassContext, RTHandle, RTHandle, Vector4, Vector4, int, float, int, int)

Vertical gaussian blur pass

Declaration

public static void VerticalGaussianBlur(in CustomPassContext ctx, RTHandle source, RTHandle destination, Vector4 sourceScaleBias, Vector4 destScaleBias, int sampleCount = 8, float radius = 5, int sourceMip = 0, int destMip = 0)

Parameters

Type	Name	Description
CustomPassContext	ctx	Custom Pass Context.
RTHandle	source	Source to use for the gaussian blur.
RTHandle	destination	Destination buffer of the gaussian blur.
Vector4	sourceScaleBias	Scale and bias to apply when sampling the source buffer
Vector4	destScaleBias	Scale and bias to apply when writing into the destination buffer.
int	sampleCount	Number of samples to use for the gaussian blur. A high number will impact performances.
float	radius	Radius in pixel of the gaussian blur.
int	sourceMip	Source mip level to sample from.
int	destMip	Destination mip level to write to.