From 023016c6a27f02c53f7597584a879c4480dc5708 Mon Sep 17 00:00:00 2001
From: sebastian <mail@sebastian.boeckelmann.de>
Date: Tue, 4 Aug 2026 14:42:57 +0200
Subject: [PATCH] ADD: SphereFactory

---
 .../src/renderer/primitives/SphereFactory.cpp | 67 +++++++++++++++++++
 .../src/renderer/primitives/SphereFactory.h   | 17 +++++
 2 files changed, 84 insertions(+)
 create mode 100644 engine/src/renderer/primitives/SphereFactory.cpp
 create mode 100644 engine/src/renderer/primitives/SphereFactory.h

diff --git a/engine/src/renderer/primitives/SphereFactory.cpp b/engine/src/renderer/primitives/SphereFactory.cpp
new file mode 100644
index 0000000..ed6699e
--- /dev/null
+++ b/engine/src/renderer/primitives/SphereFactory.cpp
@@ -0,0 +1,67 @@
+//
+// Created by sebastian on 04.08.26.
+//
+
+#include "SphereFactory.h"
+
+#include <cmath>
+#include <vector>
+
+#include "utils/openglWrapper/openglObjects/Vao.h"
+
+std::shared_ptr<engine::Model> engine::SphereFactory::createUVSphere(float radius, int sectorCount, int stackCount) {
+    constexpr float PI = 3.14159265358979323846f;
+
+    // Vertices: (stackCount + 1) Ringe entlang der Breitengrade, je (sectorCount + 1) Punkte
+    // entlang der Längengrade (der letzte Punkt dupliziert den ersten, damit das Index-Gitter
+    // pro Segment gleichförmig bleibt).
+    std::vector<float> vertices;
+    vertices.reserve(static_cast<std::size_t>(stackCount + 1) * (sectorCount + 1) * 3);
+
+    for (int i = 0; i <= stackCount; ++i) {
+        const float stackAngle = PI / 2.0f - static_cast<float>(i) * PI / static_cast<float>(stackCount); // +pi/2 .. -pi/2
+        const float xy = radius * std::cos(stackAngle);
+        const float z  = radius * std::sin(stackAngle);
+
+        for (int j = 0; j <= sectorCount; ++j) {
+            const float sectorAngle = static_cast<float>(j) * 2.0f * PI / static_cast<float>(sectorCount); // 0 .. 2pi
+            vertices.push_back(xy * std::cos(sectorAngle)); // x
+            vertices.push_back(xy * std::sin(sectorAngle)); // y
+            vertices.push_back(z);                          // z
+        }
+    }
+
+    // Indices: zwei Dreiecke pro Gitterzelle; die Kappen am Pol lassen das jeweils
+    // entartete Dreieck aus.
+    std::vector<unsigned int> indices;
+    indices.reserve(static_cast<std::size_t>(stackCount) * sectorCount * 6);
+
+    for (int i = 0; i < stackCount; ++i) {
+        unsigned int k1 = static_cast<unsigned int>(i * (sectorCount + 1)); // Anfang des aktuellen Rings
+        unsigned int k2 = k1 + static_cast<unsigned int>(sectorCount + 1);  // Anfang des nächsten Rings
+
+        for (int j = 0; j < sectorCount; ++j, ++k1, ++k2) {
+            if (i != 0) {
+                indices.push_back(k1);
+                indices.push_back(k2);
+                indices.push_back(k1 + 1);
+            }
+            if (i != stackCount - 1) {
+                indices.push_back(k1 + 1);
+                indices.push_back(k2);
+                indices.push_back(k2 + 1);
+            }
+        }
+    }
+
+    auto vao = Vao::create();
+
+    std::vector<std::unique_ptr<Attribute>> attribs;
+    attribs.push_back(std::make_unique<Vec3Attribute>(0));
+    vao->initDataFeed(vertices.data(), vertices.size() * sizeof(float), GL_STATIC_DRAW, std::move(attribs));
+
+    vao->createIndexBuffer(indices.data(), indices.size());
+    vao->unbind();
+
+    return std::make_shared<Model>(std::move(vao), static_cast<int>(indices.size()), true);
+}
diff --git a/engine/src/renderer/primitives/SphereFactory.h b/engine/src/renderer/primitives/SphereFactory.h
new file mode 100644
index 0000000..aababa9
--- /dev/null
+++ b/engine/src/renderer/primitives/SphereFactory.h
@@ -0,0 +1,17 @@
+//
+// Created by sebastian on 04.08.26.
+//
+
+#ifndef COLORRACE_SPHEREFACTORY_H
+#define COLORRACE_SPHEREFACTORY_H
+#include <memory>
+
+#include "loader/models/Model.h"
+
+namespace engine::SphereFactory {
+    // Erzeugt eine UV-Sphere mit gegebenem Radius (Radius ist in die Vertices eingebacken,
+    // die Transform braucht also nur eine Translation auf das Kugelzentrum).
+    std::shared_ptr<Model> createUVSphere(float radius, int sectorCount = 16, int stackCount = 12);
+}
+
+#endif //COLORRACE_SPHEREFACTORY_H