82 lines
3.7 KiB
HLSL
82 lines
3.7 KiB
HLSL
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// SDF Function for rectangle
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float rectangle(float2 samplePosition, float2 halfSize){
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// X component represents signed distance to closest vertical edge of rectangle
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// Same for Y but for closest horizontal edge
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// HalfSize represents two distances from each axis of 2d space to a сorresponding edge
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float2 distanceToEdge = abs(samplePosition) - halfSize;
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// max(n, 0) to remove distances that signed with minus (distances inside rectangle)
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// length to calculate distance from outside (distances that > 0) to rectangle
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float outsideDistance = length(max(distanceToEdge, 0));
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// max(x,y) is a cheap way to calculate distance to closest edge inside rectangle
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// with min we just make sure that inside distances would not impact on outside distances
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float insideDistance = min(max(distanceToEdge.x, distanceToEdge.y), 0);
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return outsideDistance + insideDistance;
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}
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// An extension of rectangle() function to modify signed distance (effect as a wrap around rectangle)
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float roundedRectangle(float2 samplePosition, float absoluteRound, float2 halfSize){
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// subtrancting value from final distance effects like a wrap around rectangle, so
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// the solution is to decrease actual rectangle with `absoluteRound` value
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// and then make an effect of wrap with size of `absoluteRound`
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return rectangle(samplePosition, halfSize - absoluteRound) - absoluteRound;
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}
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// Smoothstep function with antialiasing
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float AntialiasedCutoff(float distance){
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float distanceChange = fwidth(distance) * 0.5;
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return smoothstep(distanceChange, -distanceChange, distance);
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}
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float CalcAlpha(float2 samplePosition, float2 size, float radius){
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// -.5 = translate origin of samplePositions from (0, 0) to (.5, .5)
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// because for Image component (0,0) is bottom-right, not a center
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// * size = scale samplePositions to localSpace of Image with this size
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float2 samplePositionTranslated = (samplePosition - .5) * size;
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float distToRect = roundedRectangle(samplePositionTranslated, radius * .5, size * .5);
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return AntialiasedCutoff(distToRect);
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}
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inline float2 translate(float2 samplePosition, float2 offset){
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return samplePosition - offset;
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}
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float intersect(float shape1, float shape2){
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return max(shape1, shape2);
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}
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float2 rotate(float2 samplePosition, float rotation){
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const float PI = 3.14159;
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float angle = rotation * PI * 2 * -1;
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float sine, cosine;
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sincos(angle, sine, cosine);
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return float2(cosine * samplePosition.x + sine * samplePosition.y, cosine * samplePosition.y - sine * samplePosition.x);
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}
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float circle(float2 position, float radius){
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return length(position) - radius;
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}
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float CalcAlphaForIndependentCorners(float2 samplePosition, float2 halfSize, float4 rect2props, float4 r){
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samplePosition = (samplePosition - .5) * halfSize * 2;
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float r1 = rectangle(samplePosition, halfSize);
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float2 r2Position = rotate(translate(samplePosition, rect2props.xy), .125);
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float r2 = rectangle(r2Position, rect2props.zw);
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float2 circle0Position = translate(samplePosition, float2(-halfSize.x + r.x, halfSize.y - r.x));
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float c0 = circle(circle0Position, r.x);
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float2 circle1Position = translate(samplePosition, float2(halfSize.x - r.y, halfSize.y - r.y));
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float c1 = circle(circle1Position, r.y);
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float2 circle2Position = translate(samplePosition, float2(halfSize.x - r.z, -halfSize.y + r.z));
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float c2 = circle(circle2Position, r.z);
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float2 circle3Position = translate(samplePosition, -halfSize + r.w);
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float c3 = circle(circle3Position, r.w);
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float dist = max(r1,min(min(min(min(r2, c0), c1), c2), c3));
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return AntialiasedCutoff(dist);
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}
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