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Vector2 getProjection(Vector2* vertices, int numVertices, Vector2 axis) {
// Find the min and max vertex projections
float32 min = axis.dot(vertices[0]);
float32 max = min;
for (int v = 1; v < numVertices; v++) {
float32 d = axis.dot(vertices[v]);
if (d < min) {
min = d;
} else if (d > max) {
max = d;
}
}
return Vector2 { min, max };
}
bool projectionsOverlap(Vector2 first, Vector2 second) {
return first.x <= second.y && second.x <= first.y;
}
bool doIntersect(ConvexPolygon* first, ConvexPolygon* second) {
IntersectionResult ir;
// Check agaisnt the edges of the first polygon
for (int i = 0; i < first->numVertices; i++) {
Vector2 normal = first->edges[i].normal;
Vector2 firstProj = getProjection(first->transformedVertices, first->numVertices, normal);
Vector2 secondProj = getProjection(second->transformedVertices, second->numVertices, normal);
if (!projectionsOverlap(firstProj, secondProj)) {
return false;
}
}
// Check against the edges of the second polygon
for (int i = 0; i < second->numVertices; i++) {
Vector2 normal = second->edges[i].normal;
Vector2 firstProj = getProjection(first->transformedVertices, first->numVertices, normal);
Vector2 secondProj = getProjection(second->transformedVertices, second->numVertices, normal);
if (!projectionsOverlap(firstProj, secondProj)) {
return false;
}
}
return true;
}
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