From d0cc59ad3ad2d7348ed82e4cd560fc9684150a1a Mon Sep 17 00:00:00 2001
From: MihailRis <mexaruc@gmail.com>
Date: Fri, 25 Sep 2026 20:37:24 +0300
Subject: [PATCH] add 'cull-face' parameter to `tri` and `rect` primitives

---
 src/coders/vcm.cpp | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/src/coders/vcm.cpp b/src/coders/vcm.cpp
index 42a503477..a1ca758de 100644
--- a/src/coders/vcm.cpp
+++ b/src/coders/vcm.cpp
@@ -198,6 +198,31 @@ static void perform_rect(const xmlelement& root, ModelBuilder& builder) {
     } else {
         normal = glm::cross(glm::normalize(right), glm::normalize(up));
     }
+
+    auto cullFace = root.attr("cull-face", "back").getText();
+    if (cullFace == "front") {
+        normal *= -1.0f;
+    } else if (cullFace == "off") {
+        builder.addRect(
+            texture,
+            shading,
+            from + right * 0.5f + up * 0.5f,
+            right * 0.5f,
+            up * 0.5f,
+            normal,
+            region
+        );
+        builder.addRect(
+            texture,
+            shading,
+            from + right * 0.5f + up * 0.5f,
+            right * -0.5f,
+            up * -0.5f,
+            -normal,
+            region
+        );
+        return;
+    }
     builder.addRect(
         texture,
         shading,
@@ -246,6 +271,17 @@ static void perform_triangle(const xmlelement& root, ModelBuilder& builder) {
     }
     
     std::string texture = root.attr("texture", "$0").getText();
+
+    auto cullFace = root.attr("cull-face", "back").getText();
+    if (cullFace == "front") {
+        std::swap(pointB, pointC);
+        std::swap(uvs[1], uvs[2]);
+        normal *= -1.0f;
+    } else if (cullFace == "off") {
+        builder.addTriangle(texture, shading, pointA, pointB, pointC, normal, uvs[0], uvs[1], uvs[2]);
+        builder.addTriangle(texture, shading, pointA, pointC, pointB, -normal, uvs[0], uvs[2], uvs[1]);
+        return;
+    }
     builder.addTriangle(texture, shading, pointA, pointB, pointC, normal, uvs[0], uvs[1], uvs[2]);
 }