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#include "geometry.h"
#include <cmath>
static const float PI = 3.1415f;
int calculateCircleVertexCount(float diameter)
{
// 10 * sqrt(r) \approx 2*pi / acos(1 - 1 / (4*r))
return int(10.0 * sqrt(diameter / 2));
}
void updateCircleGeometry(QSGGeometry *geometry, float diameter, float cx, float cy)
{
int vertexCount = geometry->vertexCount();
float theta = 2 * PI / float(vertexCount);
float c = cosf(theta);
float s = sinf(theta);
float x = diameter / 2;
float y = 0;
QSGGeometry::Point2D *vertexData = geometry->vertexDataAsPoint2D();
for (int i = 0; i < vertexCount; i++) {
vertexData[i].set(x + cx, y + cy);
float t = x;
x = c*x - s*y;
y = s*t + c*y;
}
}
void updateRectGeometry(QSGGeometry *geometry, float x, float y, float w, float h)
{
QSGGeometry::Point2D *vertexData = geometry->vertexDataAsPoint2D();
vertexData[0].set(x, y);
vertexData[1].set(x + w, y);
vertexData[2].set(x + w, y + h);
vertexData[3].set(x, y + h);
}
void updateCrossHairGeometry(QSGGeometry *geometry,
float x,
float y,
float thickness,
float length)
{
QSGGeometry::Point2D *vertexData = geometry->vertexDataAsPoint2D();
if (geometry->vertexCount() != 12) {
return;
}
vertexData[ 0].set(x + thickness, y - thickness);
vertexData[ 1].set(x + length, y - thickness);
vertexData[ 2].set(x + length, y + thickness);
vertexData[ 3].set(x + thickness, y + thickness);
vertexData[ 4].set(x + thickness, y + length);
vertexData[ 5].set(x - thickness, y + length);
vertexData[ 6].set(x - thickness, y + thickness);
vertexData[ 7].set(x - length, y + thickness);
vertexData[ 8].set(x - length, y - thickness);
vertexData[ 9].set(x - thickness, y - thickness);
vertexData[10].set(x - thickness, y - length);
vertexData[11].set(x + thickness, y - length);
}
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