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Arc Expand Optimizations #4994

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Arc Expand Optimizations #4994

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30ee87a
Arc Expand Optmizations
Brandon502 Oct 9, 2025
8c087b9
Arc Optimizations 2
Brandon502 Oct 10, 2025
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62 changes: 31 additions & 31 deletions wled00/FX_fcn.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -663,7 +663,7 @@ uint16_t Segment::virtualLength() const {
vLen = max(vW,vH); // get the longest dimension
break;
case M12_pArc:
vLen = sqrt32_bw(vH*vH + vW*vW); // use diagonal
vLen = (sqrt32_bw((vH*vH + vW*vW) << 2) + 1) >> 1; // diagonal rounded
break;
case M12_sPinwheel:
vLen = getPinwheelLength(vW, vH);
Expand Down Expand Up @@ -742,36 +742,28 @@ void WLED_O2_ATTR Segment::setPixelColor(int i, uint32_t col) const
if (vStrip > 0) setPixelColorRaw(XY(vStrip - 1, vH - i - 1), col);
else for (int x = 0; x < vW; x++) setPixelColorRaw(XY(x, vH - i - 1), col);
break;
case M12_pArc:
// expand in circular fashion from center
if (i == 0)
setPixelColorRaw(XY(0, 0), col);
else {
float r = i;
float step = HALF_PI / (2.8284f * r + 4); // we only need (PI/4)/(r/sqrt(2)+1) steps
for (float rad = 0.0f; rad <= (HALF_PI/2)+step/2; rad += step) {
int x = roundf(sin_t(rad) * r);
int y = roundf(cos_t(rad) * r);
// exploit symmetry
setPixelColorXY(x, y, col);
setPixelColorXY(y, x, col);
case M12_pArc: {
// expand in circular fashion from top left corner
// Tony Barrera's circle algorithm
// https://softwareengineering.stackexchange.com/questions/287478/drawing-concentric-circles-without-gaps/357445#357445

if (i == 0) setPixelColorXYRaw(0, 0, col); // 0 and 2 special cases to prevent square
else if (i == 2) setPixelColorXYRaw(1, 1, col);
else if (i == vLength()-1) setPixelColorXYRaw(vW-1, vH-1, col); // last i always draws bottom right corner

int x = 0, y = i; // i is the radius
int d = -(i >> 1); // Initial decision parameter

while (x <= y) {
if (i != x || i != y) { // prevent early square
if (y < vH && x < vW) setPixelColorXYRaw(x, y, col);
if (y < vW && x < vH) setPixelColorXYRaw(y, x, col);
}
// Bresenham’s Algorithm (may not fill every pixel)
//int d = 3 - (2*i);
//int y = i, x = 0;
//while (y >= x) {
// setPixelColorXY(x, y, col);
// setPixelColorXY(y, x, col);
// x++;
// if (d > 0) {
// y--;
// d += 4 * (x - y) + 10;
// } else {
// d += 4 * x + 6;
// }
//}
if (d <= 0) d += ++x;
else d -= --y;
}
break;
}
case M12_pCorner:
for (int x = 0; x <= i; x++) setPixelColorXY(x, i, col); // note: <= to include i=0. Relies on overflow check in sPC()
for (int y = 0; y < i; y++) setPixelColorXY(i, y, col);
Expand Down Expand Up @@ -947,9 +939,17 @@ uint32_t WLED_O2_ATTR Segment::getPixelColor(int i) const
else { y = vH - i - 1; };
break;
case M12_pArc:
if (i > vW && i > vH) {
x = y = sqrt32_bw(i*i/2);
break; // use diagonal
if (i >= vW && i >= vH) { // Barrera's circle algorithm
x = vW - 1; y = vH - 1; // default to bottom right if not found
int x2 = 0, y2 = i, d = -(i >> 1);
int validCount = 0; // return 2nd non mirrored pixel if available
while (x2 <= y2 && validCount < 2) {
if (y2 < vH && x2 < vW) {x = x2, y = y2; validCount++;}
else if (y2 < vW && x2 < vH) {x = y2, y = x2; validCount++;}

if (d <= 0) d += ++x2; else d -= --y2;
}
break;
}
// otherwise fallthrough
case M12_pCorner:
Expand Down