How can we use the smoothstep function in renderscript to smoothen a mask image (already blurred using gaussian blur with kernel size 3 or 5) and make its edges smoother. I tried the following code in other frameworks and they worked as expected.
iOS shader code:-
let kernelStr = """
kernel vec4 myColor(__sample source) {
float maskValue = smoothstep(0.3, 0.5, source.r);
return vec4(maskValue,maskValue,maskValue,1.0);
}
"""
In opengl glsl fragment shader:-
float mask = btex.r;
float maskValue = smoothstep(0.3, 0.5, mask);
vec4 ress = vec4(maskValue,maskValue,maskValue,1.0);
RenderScript doesn't have a buit-in smoothstep function, so the simplest thing is to implement it yourself. Next the source ready to be used in your scripts:
static inline float smoothstep(float edge0, float edge1, float x)
{
float value = clamp((x - edge0) / (edge1 - edge0), 0.0f, 1.0f);
return value * value * (3.0f - 2.0f * value);
}
Example of usage:
static inline float smoothstep(float edge0, float edge1, float x)
{
float value = clamp((x - edge0) / (edge1 - edge0), 0.0f, 1.0f);
return value * value * (3.0f - 2.0f * value);
}
uchar4 RS_KERNEL root(uint32_t x, uint32_t y)
{
....
float mask = btex.r;
float maskValue = smoothstep(0.3f, 0.5f, mask);
float4 ress = (float4){maskValue, maskValue, maskValue, 1.0f};
....
}
And next a link about how smoothstep internally works, in case you have any other doubts:
Enjoy
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