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UUSL Semantics

Redefined UUSL semantics allows you to create unified input\output shader structures for both graphics APIs.

Vertex Shader Semantics#

Vertex shader semantics contain necessary input and output data for shader. You should initialize variables first and then use them.

UUSL OpenGL Direct3D Description
INIT_ATTRIBUTE(TYPE,NUM,SEMANTICS) in TYPE s_attribute_ ## NUM; TYPE attribute_ ## NUM : SEMANTICS; Adds a semantic to a vertex shader variable.
INIT_OUT(TYPE,NUM) out TYPE s_texcoord_ ## NUM; TYPE data_ ## NUM : TEXCOORD ## NUM; Adds an output data semantic.
INIT_POSITION - float4 position : SV_POSITION; Adds a position system-value semantic.
INIT_INSTANCE - uint instance : SV_INSTANCEID; Adds a per-instance identifier system-value semantic.

Here is an example of vertex shader input and output structures:

UUSL
// Input vertex data
STRUCT(VERTEX_IN)
	INIT_ATTRIBUTE(float4,0,POSITION)	// Vertex position
	INIT_ATTRIBUTE(float4,1,TEXCOORD0)	// Vertex texcoord (uv)
	INIT_ATTRIBUTE(float4,2,TEXCOORD1)	// Vertex basis tangent
	INIT_ATTRIBUTE(float4,3,TEXCOORD2)	// Vertex color
END

// Our output vertex data
STRUCT(VERTEX_OUT)
	INIT_POSITION		// Out projected position
	INIT_OUT(float4,0)	// Texcoord (uv)
	INIT_OUT(float3,1)	// Vertex direction
END
Warning
You should add a new line (press Enter) after closing the instruction.

Use the following pre-defined variables to use the input\output vertex shader semantics:

UUSL OpenGL Direct3D Description
IN_INSTANCE gl_InstanceID input.instance An input per-instance identifier system-value variable.
IN_ATTRIBUTE(NUM) s_attribute_ ## NUM input.attribute_ ## NUM An input shader variable.
OUT_DATA(NUM) s_texcoord_ ## NUM output.data_ ## NUM An output texture coordinates variable.
OUT_POSITION gl_Position output.position An output position system-value variable.

Fragment Shader Semantics#

Fragment shader semantics contain necessary input and output data for shader. You should initialize variables first and then use them.

UUSL OpenGL Direct3D Description
INIT_IN(TYPE,NUM) in TYPE s_texcoord_ ## NUM; TYPE data_ ## NUM : TEXCOORD ## NUM; Adds an input texture coordinates semantic.
INIT_COLOR(TYPE) out TYPE s_frag_color; TYPE color : SV_TARGET; Add an output diffuse or specular color semantic (single RT).
INIT_DEPTH - float depth : SV_DEPTH; Add an output depth system-value semantic.
INIT_MRT(TYPE,NUM) out TYPE s_frag_data_ ## NUM; TYPE color_ ## NUM : SV_TARGET ## NUM; Add an output color system-value semantic (some RTs).
INIT_FRONTFACE --- bool frontface : SV_ISFRONTFACE; Adds an input semantic indicates primitive face (frontface or not).

To use the variables in the code, use the following variables:

UUSL OpenGL Direct3D Description
IN_POSITION gl_FragCoord input.position An input position value.
IN_DATA(NUM) s_texcoord_ ## NUM input.data_ ## NUM An input texture coordinates variable.
IN_FRONTFACE !gl_FrontFacing input.frontface Floating-point scalar that indicates a back-facing primitive. A negative value faces backwards, while a positive value faces the camera.
OUT_COLOR s_frag_color output.color An output color value (single RT).
OUT_DEPTH gl_FragDepth output.depth An output depth value.
OUT_MRT(NUM) out TYPE s_frag_data_ ## NUM; output.color_ ## NUM An output color value for MRTs.

Here is a simple example of using the variable in the main function of the shader:

USUL
MAIN_BEGIN(FRAGMENT_OUT,FRAGMENT_IN)
	
	float4 texcoord = IN_DATA(0);

	/* ... other code ... */
END
Warning
You should add a new line (press Enter) after closing the instruction.

Geometry Shader Semantics#

UUSL OpenGL Direct3D Description
INIT_GEOM_IN(TYPE,NUM) in TYPE s_geom_texcoord_ ## NUM[]; TYPE data_ ## NUM : TEXCOORD ## NUM; Add an input texture coordinates semantic for the geometry-shader stage.
INIT_GEOM_OUT(TYPE,NUM) out TYPE s_geom_texcoord_ ## NUM; TYPE data_ ## NUM : TEXCOORD ## NUM; Add an output texture coordinates semantic for the geometry-shader stage.
UUSL OpenGL Direct3D Description
IN_GEOM_DATA(NUM,INDEX) s_geom_texcoord_ ## NUM ## [INDEX] input[INDEX].data_ ## NUM An input texture coordinates value.
IN_GEOM_POSITION(INDEX) gl_in[INDEX].gl_Position input[INDEX].position An input position value.
OUT_GEOM_DATA(NUM) s_geom_texcoord_ ## NUM output.data_ ## NUM An output texture coordinates value.
TRIANGLE_IN triangles triangle Input primitive type: triangle list or triangle strip.
TRIANGLE_OUT triangle_strip TriangleStream Output primitive type: a sequence of triangle primitives
LINE_IN lines line Input primitive type: line.
LINE_OUT line_strip LineStream Output primitive type: a sequence of line primitives

Unified Shader Semantics#

Unified shader semantics allows you to create single structure for both vertex and fragment shaders. It facilities the work with vertex and fragment shaders input/output structure by using single structure for both shaders: this structure will be output for vertex shader and input for fragment shader respectively.

You can write vertex and fragment shader in a single file with .shader extension. In this case, in the material you should specify this .shader file for both shader stages.

Source code (XML)
<materials version="2.0" editable="0">
	<material name="mesh_base" editable="0" parameters_prefix="m" defines="VERTEX_ATTRIBUTE_GEOMETRY">
		<!-- ... -->
		<shader pass="auxiliary" object="mesh_static"
				auxiliary="1"
				defines="BASE_AUXILIARY"
				vertex="core/shaders/mesh/auxiliary/auxiliary.shader"
				fragment="core/shaders/mesh/auxiliary/auxiliary.shader"/>
		<!-- ... -->
	</material>
</materials>
UUSL VERTEX FRAGMENT Description
INIT_DATA(TYPE,NUM,NAME) INIT_OUT(TYPE,NUM) \ #define NAME GET_DATA(NUM) INIT_IN(TYPE,NUM) \ #define NAME GET_DATA(NUM) Data initialization.
GET_DATA(V) OUT_DATA(V) IN_DATA(V) Helper for getting/setting data by using data name.

IF statement#

There is also a IF_DATA(NAME) statement to execute an operation if the data is not null.

UUSL VERTEX FRAGMENT Description
IF_DATA(NAME) #ifdef NAME #ifdef NAME Opening IF conditional statement.
ENDIF #endif #endif Closing IF conditional statement.

Here is a code snippet of shader, where shader's IF statement is used.

UUSL
//input struct
STRUCT(FRAGMENT_IN)
/* ... */
	#ifdef ALPHA_FADE && USE_ALPHA_FADE
		INIT_DATA(float,1,DATA_ALPHA_FADE)
	#endif
/* ... */
END

//main functions
MAIN_SHADOW_BEGIN(FRAGMENT_OUT,FRAGMENT_IN)
/* ... */
	IF_DATA(DATA_ALPHA_FADE)
		//code to execute if the data is not null
		texture2DAlphaFadeDiscard(DATA_ALPHA_FADE,IN_POSITION.xy);
	ENDIF
/* ... */
MAIN_SHADOW_END
Last update: 2017-07-03