Detailed Description

Specialization of ExprBaseTpl for a variable, e.g.

a result of another computation which is not yet available during creation of the expr. Only one per expression is allowed at current.

Each expression may contain one Variable. This is a placeholder variable which can be used to use intermediate results directly within your expression or e.g. to use the result of a computation within your shader directly within your expression. In order to substitute such a variable on the CPU you can use VariableSubstitutionOp operator while on the GPU there is a specific argument you can pass. This feature can also be used in combination with the polymorphic interface. Meaning you can have different code paths for you CPU/GPU execution and still patch in different expressions.

The most common use case would be like this: Assume you have some computation based on a target and a source image. Now let us further assume that you want to flexibly apply an expression to either of those two images for whatever reason. One example would be DRR generation where you want to apply an exponential function if you want to display attenuation images.

Example:

void compute(ExprBase expr, bool useGPU)
{
  if(useGPU)
  {
    // create a GlExpr which is a GlAbstractInclude
    GlExpr exprInclude(expr);
    // this will add a function `vec4 exprVal(vec3 tc, vec4 varval)` to your shader.
    // The shader would now compute the raycasting and would call exprVal with the result of the reycasting as second argument
  } else { // CPU case
    // In this case you need to compute the values for the variable and store them in an image.
    SharedImage vars(...);
    // Compute the raycasting on the CPU and store the result in vars
    ...
    // Now you can apply the expression. The variable entry will automatically be substituted
    // with the corresponding value from the vars image.
    expr.eval(..., vars);
}
 
void ()
{
  if(/* apply exp function*/)
    compute((-Variable()).exp().polyWrapper());
  else
    compute(Variable().polyWrapper());
}

The big advantage of this approach is that the code in the compute() function and the involved shader are completely independent from the actual expression.

Public Types
using	expr_type = void

using	var_type = void

using	imf_img_type = void

Public Member Functions
	Variable (int channels)

template<typename ImgT>
auto	convertToMemImgExpr () const noexcept

auto	convertToSharedImgExpr (std::size_t) const

template<typename SubOperandT>
auto	substituteVariable (const SubOperandT &operand) const
	Substitutes any Variable leaf.

ImageDescriptor	imgDesc () const override
	Return ImageDescriptor of this expression. This reference is expected to remain the same while the class exists.

int	numImgs () const override
	Return number of images of this expression.

DeviceStrategy	deviceStrategy () const override
	Return DeviceStrategy of this expression.

Public Member Functions inherited from ExprBaseTpl< Variable >
const auto &	get () const
	get a const reference to this with the actual type

auto &	get ()
	get a reference to this with the actual type

auto	polyWrapper () const

auto	uniquePolyWrapper () const

auto	sharedPolyWrapper () const

auto	binaryOp (const ExprBaseTpl< RhsT > &rhs, const Op &func=Op()) const

auto	binaryOp (RhsT rhs, const Op &func=Op(), typename std::enable_if< std::is_arithmetic_v< RhsT > >::type *=nullptr) const

auto	binaryOp (Eigen::Matrix< RhsT, Dim, 1, Options, MaxRows, MaxCols > rhs, const Op &func=Op(), typename std::enable_if< std::is_arithmetic_v< RhsT > >::type *=nullptr) const

auto	binaryOp (const ExprBaseTpl< RhsT > &rhs, const Op &func, const StringOp &stringFunc) const

auto	binaryOp (RhsT rhs, const Op &func, const StringOp &stringFunc, typename std::enable_if< std::is_arithmetic_v< RhsT > >::type *=nullptr) const

auto	binaryOp (Eigen::Matrix< RhsT, Dim, 1, Options, MaxRows, MaxCols > rhs, const Op &func, const StringOp &stringFunc, typename std::enable_if< std::is_arithmetic_v< RhsT > >::type *=nullptr) const

auto	unaryOp (const Op &func=Op()) const

auto	unaryOp (const Op &func, const StringOp &stringFunc) const

reduction_type	reduce (std::vector< vec4i > *arg=nullptr) const

auto	forceCPU () const
	Forces CPU execution.

auto	forceGPU () const
	Forces GPU execution.

auto	channelSwizzle (const std::vector< std::size_t > &indices) const

auto	head ()

	ADD_SPECIAL_SWIZZLE (x, {0})

	ADD_SPECIAL_SWIZZLE (y, {1})

	ADD_SPECIAL_SWIZZLE (z, {2})

	ADD_SPECIAL_SWIZZLE (w, {3})

	ADD_SPECIAL_SWIZZLE (r, {0})

	ADD_SPECIAL_SWIZZLE (g, {1})

	ADD_SPECIAL_SWIZZLE (b, {2})

	ADD_SPECIAL_SWIZZLE (a, {3})

	ADD_SPECIAL_SWIZZLE (xy, std::vector< size_t >({0, 1}))

	ADD_SPECIAL_SWIZZLE (rg, std::vector< size_t >({0, 1}))

	ADD_SPECIAL_SWIZZLE (xyz, std::vector< size_t >({0, 1, 2}))

	ADD_SPECIAL_SWIZZLE (xyzw, std::vector< size_t >({0, 1, 2, 3}))

	ADD_SPECIAL_SWIZZLE (rgb, std::vector< size_t >({0, 1, 2}))

	ADD_SPECIAL_SWIZZLE (rgba, std::vector< size_t >({0, 1, 2, 3}))

auto	streamChannels (int numStreamedChannels) const

auto	substituteVariableWithImg (T &img) const

auto	operator- () const

auto	cast () const

auto	storageToOriginal (const ImageDescriptor &desc)
	Apply shift/scale to the operand,.

auto	originalToStorage (const ImageDescriptor &desc)
	Apply shift/scale to the operand,.

auto	channelReduction ()

	ADD_CHANNEL_REDUCTION_OPERATOR (channelSum, add)

	ADD_CHANNEL_REDUCTION_OPERATOR (channelProd, mult)

	ADD_CHANNEL_REDUCTION_OPERATOR (channelMax, max)

	ADD_CHANNEL_REDUCTION_OPERATOR (channelMin, min)

	ADD_CHANNEL_REDUCTION_OPERATOR (length, length)

auto	channelMean ()

auto	squaredLength () const

auto	channelDistance (const ExprBaseTpl< RhsT > &other) const

auto	channelDistance (const Eigen::Matrix< T, Dim, 1 > c)

auto	dot (const ExprBaseTpl< RhsT > &other) const

auto	stashThenApply (const ExprBaseTpl< VariableT > &varExpr) const

auto	hnormalized () const

auto	normalized () const

auto	homogeneous () const

auto	appendZero () const

auto	select (const ExprBaseTpl< LhsT > &lhs, const ExprBaseTpl< RhsT > &rhs) const
	Ternary (condition.x ? if_true : if_false) operator.

auto	select (LhsT lhs, RhsT rhs, typename std::enable_if< std::is_arithmetic_v< LhsT > &&std::is_arithmetic_v< RhsT > >::type *=nullptr) const
	Ternary (condition.x ? if_true : if_false) operator.

auto	select (LhsT lhs, const ExprBaseTpl< RhsT > &rhs, typename std::enable_if< std::is_arithmetic_v< LhsT > >::type *=nullptr) const
	Ternary (condition.x ? if_true : if_false) operator.

auto	select (const ExprBaseTpl< LhsT > &lhs, RhsT rhs, typename std::enable_if< std::is_arithmetic_v< RhsT > >::type *=nullptr) const
	Ternary (condition.x ? if_true : if_false) operator.

	ADD_REDUCTION_OPERATOR (sum, add)

	ADD_REDUCTION_OPERATOR (prod, mult)

	ADD_ARG_REDUCTION_OPERATOR (min, min)

	ADD_ARG_REDUCTION_OPERATOR (max, max)

Eigen::Matrix< double, Eigen::Dynamic, 1 >	mean () const

Eigen::Matrix< double, Eigen::Dynamic, 1 >	l1Norm () const

Eigen::Matrix< double, Eigen::Dynamic, 1 >	squaredl2Norm () const

Eigen::Matrix< double, Eigen::Dynamic, 1 >	l2Norm () const

Eigen::Matrix< double, Eigen::Dynamic, 1 >	lpNorm (double p) const

Eigen::Matrix< double, Eigen::Dynamic, 1 >	lInfNorm () const

auto	evaluateIntoImage (bool clearShiftScale=false) const
	Create an empty image and evaluate this expression into it.

auto	toMask () const

auto	toDeformation (const ImageDescriptorWorld imgDesc) const

auto	resample (const ImageDescriptorWorld &inputDesc, const ImageDescriptorWorld &outputDesc) const

auto	resample (SharedImage &inputDesc, SharedImage &outputDesc, std::enable_if_t< std::is_same_v< T, SharedImage > > *=nullptr) const

auto	resample (SharedImageSet &inputDesc, SharedImageSet &outputDesc, std::enable_if_t< std::is_same_v< T, SharedImageSet > > *=nullptr) const

Public Member Functions inherited from VariableGl
std::string	evalString (bool) const override
	Print expression.

void	tagAndAssignNames (std::unordered_map< TaggingIndex, const void * > &, std::unordered_map< std::type_index, int > &, const std::string &) const override
	We need to tag leaves and tell unique leaves that they are responsible to define the uniforms and set the shader arguments.

void	getUniformDefinitionList (std::string &, const std::vector< int > &, const std::string &) const override
	Collect uniform/sampler definitions.

void	getVariableDefinitionList (std::string &, const std::vector< int > &, const std::string &) const override
	Collect variable definitions.

int	setArguments (GL::Program &, const std::vector< int > &, const std::string &) const override
	Set uniform/sampler arguments.

std::vector< internal::GlExprInterface * >	children () override
	Used for traversing the expression tree. Contains the immediate children of node.

std::vector< const internal::GlExprInterface * >	children () const override
	Used for traversing the expression tree. Contains the immediate children of node.

Public Member Functions inherited from GlExprInterface
ExprInterface &	exprInterface ()
	Get image descriptor of the wrapped expression.

const ExprInterface &	exprInterface () const

virtual bool	setMagFilter (ImageMath::MagFilter mag)
	Set interpolation behaviour of the current leaf (only)

virtual bool	setWrap (ImageMath::Wrap wrap)
	Set interpolation behaviour of the current leaf (only)

bool	setMagFilterRecursive (ImageMath::MagFilter mag)
	Set interpolation behaviour of the current leaf and all of its children.

bool	setWrapRecursive (ImageMath::Wrap wrap)
	Set wrap behaviour of the current leaf and all of its children.

Static Public Attributes
static constexpr bool	has_variable = true

Member Function Documentation

◆ imgDesc()

ImageDescriptor imgDesc ( ) const

inlineoverridevirtual

Return ImageDescriptor of this expression. This reference is expected to remain the same while the class exists.

Implements ExprInterface.

◆ numImgs()

int numImgs ( ) const

inlineoverridevirtual

Return number of images of this expression.

Implements ExprInterface.

◆ deviceStrategy()

DeviceStrategy deviceStrategy ( ) const

inlineoverridevirtual

Return DeviceStrategy of this expression.

Implements ExprInterface.

The documentation for this class was generated from the following file:

ImFusion/ImageMath/Tpl/Variable.h

Detailed Description

Public Types

Public Member Functions

Static Public Attributes

Member Function Documentation

◆ imgDesc()

◆ numImgs()

◆ deviceStrategy()