Basic syntax for HLSL

Basic syntax for HLSL 1 data types

1.1 Scalar types

1. Bool:true or FALSE. Note that the HLSL provides the true and False keywordslike in C + +.
2. Int:32-bit Signedinteger.
3. Half:16-bit-floatingpoint number.
4. Float:32-bit-floatingpoint number.
5. Double:64-bit-floatingpoint number.

1.2 Vector type

1.2.1 Vector type

1. float2:2d vector, wherethe components is of type float.
2. Float3:3d vector, wherethe components is of type float.
3. float4:4d vector, wherethe components is of type float.

In addition to float, we can also use other basic types to define vectors, such as bool2,int3. In short, the expression type of the vector is Typen, where n belongs to (2,4).

Initialization of the 1.2.2 vector

Float3 v = {1.0f, 2.0f, 3.0f};
Float2 w = float2 (x, y);
Float4 u = float4 (W, 3.0f, 4.0f); U= (w.x, W.y, 3.0f, 4.0f)

Access to 1.2.3 vectors

With array syntax:

such as: vec[i] = 2.0f;

Use letter syntax, Xyzw,rgba.

Such as:

vec.x = VEC.R = 1.0f;
Vec.y = VEC.G = 2.0f;
Vec.z = VEC.B = 3.0f;
VEC.W = VEC.A = 4.0f;

1.2.4 Vector substitution leveling (swizzles)

To avoid the complexity of vector assignment, HLSL takes a swizzles approach, as follows:

Float4 u = {1.0f, 2.0f, 3.0f, 4.0f};
Float4 v = {0.0f, 0.0f, 5.0f, 6.0f};

v = u.wyyx; v = {4.0f, 2.0f, 2.0f,1.0f}

v = u.wzyx; v = {4.0f, 3.0f, 2.0f,1.0f}

V.xy = u; v = {1.0f, 2.0f, 5.0f,6.0f}

1.3 Matrix Types

Definition syntax for 1.3.1 matrices

TYPEMXN xxx, such as:

1. float2x2:2x2 matrix, where theentries is of type float.
2. half3x3:3x3 Matrix, where theentries is of type half.
3. int4x4:4x4 Matrix, where theentries is of type int.
4. bool3x4:3x4 Matrix, where theentries is of type bool.

Access to the 1.3.2 matrix

With array syntax:

M[i] [j] = value;

With member variable syntax:

M._11 = M._12 = m._13 = M._14 = 0.0f;
m._21 = m._22 = m._23 = m._24 = 0.0f;
m._31 = m._32 = m._33 = m._34 = 0.0f;
m._41 = m._42 = m._43 = m._44 = 0.0f;

Or

m._m00 = M._M01 = m._m02 = M._m03 =0.0f;
M._M10 = M._M11 = M._m12 = M._m13 =0.0f;
M._M20 = M._m21 = M._M22 = M._m23 =0.0f;
M._M30 = M._M31 = M._m32 = M._m33 =0.0f;

Entire row of Access:

FLOAT3 N = normalize (PIN.NORMALW);
FLOAT3 T = Normalize (Pin.tangentw-dot (PIN.TANGENTW, N) *n);
FLOAT3 B = Cross (n,t);
float3x3 TBN;
Tbn[0] = T; Sets row 1
TBN[1] = B; Sets Row 2
TBN[2] = N; Sets Row 3

Initialization of the 1.3.3 matrix

float2x2 FXX =float2x2 (1.0f,2.0f,3.0f,4.0f);

int2x2 Ixx ={1,2,3,4};

Alternative definition of 1.3.4 array vectors

Vector u = {1.0f, 2.0f, 3.0f, 4.0f};
Matrix M; 4x4 matrix

1.4 Arrays

float M[4] [4];
Half p[4];
FLOAT3 v[12]; 3D vectors

1.5 Structural bodies

The struct in HLSL is similar to a struct in C, which cannot contain function members, and access members only need to be based on subscripts.

struct SURFACEINFO
{
FLOAT3 POS;
FLOAT3 Normal;
FLOAT4 Diffuse;
FLOAT4 spec;
};
Surfaceinfo v;
Litcolor + = V.diffuse;
Dot (Lightvec, v.normal);
float specpower = max (V.SPEC.A, 1.0f);

1.6 Keywords related to variables

typedef , Static , Uniform , extern , Const

Usage is similar to C + +, when the variable is declared static, it is an internal variable and is not visible outside the shader program. Non-static global variables are extern by default, which means they can be accessed by programs outside of the shader program.

1.7 Forced type conversions

The type conversions in HLSL are very flexible, as follows:

float F = 5.0f;
float4x4 m = (float4x4) F; Copy Finto each entry of M.

FLOAT3 n = float3 (...);
FLOAT3 v = 2.0f*n-1.0f;

The 1.0f here is actually converted into (1.0f,1.0f,1.0f);

2 Syntax and functions

2.1 Syntax

2.1.1 Return

return (expression);

2.1.2 If-else Statements

if (condition)

{}

..........................................

if (condition)

{}

Else

{}

2.1.3 For Loop

for (Initial;condition;increament)

{}

2.14 While

while (condition)

{}

2.1.5do-while

Do

{}while (condition);

2.2 Functions

Features of the 2.2.1 HLSL function

Like C + +, parameters are passed by value (references and pointers are not supported), recursion is not supported, functions are always inline

Examples of 2.2.2 functions

BOOL Foo (in const bool B, out int r1,inout float R2)

{

if (b)//test input value

{

r1= 5; Output a value through R1

}

Else

{

R1 = 1; Output a value through R1

}

Sincer2 is inout we can use it as an input value and also output a value through it
r2= R2 * R2 * R2;

Returntrue;

}

Here's what you need to explain is the keyword In,out,inout

In: Default, can not add. That indicates that a parameter value must be passed.

Out: Indicates that the parameter is a return value of the function and is used only as output, not as input

InOut: Both input and output can be

Semantics (semantics) in 3 HLSL

It is often used to define HLSL either as a parameter variable entered in a function or as a variable that is returned, as in the case of Xxx:position, a place where variables in HLSL are different. ': ' is called semantics, and it is used to describe some information about variables, in essence semantics is to specify the relationship between shader variables and hardware, for example position specifies that the variable is a register that is used in the location-related.

3.1 Semantics of vertex shaders

Semantics have input and output parts, and the input and output of vertices are shown below:

Input	Description	Type
Binormal[n]	Binormal	Float4
Blendindices[n]	Blend Indices	UInt
Blendweight[n]	Blend weights	Float
Color[n]	Diffuse and specular color	Float4
Normal[n]	Normal Vector	Float4
Position[n]	Vertex position in object space.	Float4
Positiont	Transformed vertex position.	Float4
Psize[n]	Point size	Float
Tangent[n]	Tangent	Float4
Texcoord[n]	Texture coordinates	Float4

Output	Description	Type
Color[n]	Diffuse or specular color	Float4
FOG	Vertex Fog	Float
Position[n]	Position of a vertex in homogenous space. Compute position in Screen-space by dividing (x, Y, Z) by W. Every vertex shader must write out a parameter with this semantic.	Float4
PSIZE	Point size	Float
Tessfactor[n]	Tessellation factor	Float
Texcoord[n]	Texture coordinates	Float4

It can be seen from the above that the semantics of the variable is not random, first it indicates the use of variables, and secondly for the input and output have special restrictions on the semantics, we can not use as input semantics to use as output.

n is the index value of the register, and the maximum value depends on the hardware support. such as POSITION1.

Semantics of 3.2 pixel shader

Input	Description	Type
Color[n]	Diffuse or specular color.	Float4
Texcoord[n]	Texture coordinates	Float4
Vface	Floating-point scalar that indicates a back-facing primitive. A negative value faces backwards, while a positive value faces the camera.	Float
vPOS	The pixel location (x, y) in screen space. To convert a Direct3D 9 shader (so uses this semantic) to a Direct3D shader, seeDirect3D 9 vPOS and Direct3D S V_position)	Float2

Output	Description	Type
Color[n]	Output Color	Float4
Depth[n]	Output depth	Float

3.3 Examples

void Skyvs (float3posl:position0,out float4 oposh:position0,out float3 oenvtex:texcoord0) {         Oposh = Mul (FLOAT4 (POS L, 1.0f), G_MATWVP). Xyww;    Oenvtex = POSL;}

/////////////////////////////////

struct outputvs{    float4         posH  : POSITION0;    FLOAT2         tex0  : TEXCOORD0;     D3D fills in for point sprites.    float  size  : PSIZE;           In pixels.}; Outputvssnowvs (float3         posl          : POSITION0,                float3    vel    : TEXCOORD0,                float      size   : TEXCOORD1,                              float      initialt:texcoord2,                                     float lifet:texcoord3) {         Outputvs Outvs = (Outputvs ) 0;         float t = g_time-initialt;         POSL = Posl + vel * t + 0.5f * G_ACC *t * t;         Outvs.posh = Mul (Float4 (POSL, 1.0f), G_MATWVP);         Outvs.size = 0.0035f * g_viewportheight* size;    return Outvs;} FLOAT4 Snowps (float2tex0:texcoord0): color{         return tex2d (Texs, tex0);}

Reference documents

"1" Introduction to 3D Game programming with DIRECTX11

"2" Semantics (DirectX HLSL) in Microsoft DirectX Sampler

Basic syntax for HLSL