Eyeon:Script/Reference/Applications/Fuse/Classes/ViewShader/SetParam

From VFXPedia

Summary

The SetParam function is used to set the value of exposed run-time parameters in the shader.

In addition to the 'ViewShader source' data member, the struct derived from the ViewShader baseclass in the shader string may also contain other data members, which can be exposed as run-time parameters. To do this, call AddParam(name), where name is the name of the data member to be exposed. This is typically done when the ViewShader object is created, in ScriptViewShader:SetupShader().

Once exposed, the value of the run-time parameter can be set with SetParam(), typically when ScriptViewShader:SetupParams() is called. Various data types are supported, including numbers, booleans, vectors, 4x4 matrices and images.

Usage

SetParam(number index, boolean bool)

SetParam(number index, number value [, number value [, number value [, number value]]])

SetParam(number index, Vector2 vec2)

SetParam(number index, Vector3f vec3)

SetParam(number index, Vector4 vec4)

SetParam(number index, Matrix4 mat4)

SetParam(number index, Image image [, table channels [, table tags]])

index (number, required)

The index of the run-time parameter to be set

image (Image, required)

An Image object.

channels (table, optional)

A table containing the string "Color", to upload RGBA, or containing four channel identifier strings from the following table:

tags (table, optional)

A table containing a series of tag and value strings, from the following table:

Returns

SetParam() has no returns.

Example

This example fetches a shaded pixel from the source and applies a simple gamma.

-- Here's the Cg shader itself:
shader = 
[[
struct GammaFuse : ViewShader
{
    ViewShader source;	                        // need this line
    float gamma;                                // run-time parameter
 
    void ShadePixel(inout FuPixel f)
    {
        source.ShadePixel(f);                   // get source pixel
 
        f.Color.rgb = pow(f.Color.rgb, gamma);  // apply simple gamma
    }
};
]]
 
 
-- This is called every display refresh
-- img may be nil
function SetupParams(req, vs, img)
    local gamma = InGamma:GetValue(req).Value;  -- retrieve our current control value
 
    if gamma ~= 0.0 then
        gamma = 1.0 / gamma;
    else
        gamma = 1000000.0;
    end
	
    vs:SetParam(gammaparam, gamma);  -- use the gammaparam index we got from AddParam() earlier
 
    return true;
end

Example of setting a point parameter:

function SetupParams(req, vs, img)
    local centerx = InCenter:GetValue(req).X;	-- retrieve control values
    local centery = InCenter:GetValue(req).Y;
 
    vs:SetParam(centerindex, centerx * imgw, centery * imgh);
end

Example of uploading an Image to a texture sampler:

-- load our img only when the filename changes, not every redraw!
function NotifyChanged(inp, param, time)
    if param then
        if inp == InFilename then
            local filename = tostring(param.Value);    -- get filename as a string
            local clip = Clip(filename);               -- make a Clip out of it (defaults to read-only)
            
            uploadimg = clip:GetFrame(0);              -- get the first frame only
        end
    end
end
 
-- upload the image (table args are optional)
function SetupParams(req, vs, img)
    vs:SetParam(imgindex, uploadimg, {"Color"}, {   -- {"Color"}, {"R","G","B","A"}, {"Z","Z","Z","A"} etc
        TR_GLTexTarget = "2D",                      -- RECT (default, pixel coords), 2D (normalized coords)
        TR_F3DTexDataType = "int8",                 -- int8, int16, float16, float32, ChooseSmallest (default)
        TR_WrapModeS = "Black",                     -- Clamp (default), Black, and (not for RECTs) Wrap, Mirror
        TR_WrapModeT = "Black",
        TR_GLMinFilter = "Linear",                  -- Linear (default), Nearest
        TR_GLMagFilter = "Linear",
    });
end

See Also

• AddParam()
• ScriptViewShader:SetupShader()
• ScriptViewShader:SetupParams()

Tips for SetParam (edit)

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