From cffe13054fac450323c6e9a745519674fcd11118 Mon Sep 17 00:00:00 2001
From: Joseph Ferano <joseph@ferano.io>
Date: Sat, 7 Mar 2026 09:50:08 +0700
Subject: [PATCH] Extract and render colors for mesh

---
 src/nol/core.clj | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/src/nol/core.clj b/src/nol/core.clj
index f335f69..342f49b 100644
--- a/src/nol/core.clj
+++ b/src/nol/core.clj
@@ -1,6 +1,6 @@
 (ns nol.core
   (:require [clojure.math])
-  (:import [org.lwjgl.assimp Assimp AIFace AIMaterial AIMesh AIScene AIVector3D]
+  (:import [org.lwjgl.assimp AIColor4D AIFace AIMaterial AIMaterial$Buffer AIMesh AIScene AIVector3D Assimp]
            [org.lwjgl.glfw GLFW GLFWErrorCallbackI GLFWKeyCallbackI]
            [org.lwjgl.opengl GL GL11 GL15 GL20 GL33 GL30 GL45]
            [org.lwjgl.system MemoryUtil MemoryStack]
@@ -62,11 +62,11 @@
       (GL20/glUseProgram program)
 
       (let [color-loc (GL20/glGetUniformLocation program "uColor")]
-        (GL20/glUniform4f color-loc 1.0 0.5 0.2 1.0))
-
-      (doseq [m meshes]
-        (GL30/glBindVertexArray (:vao m))
-        (GL11/glDrawElements GL11/GL_TRIANGLES (:indices-count m) GL11/GL_UNSIGNED_INT 0))
+        (doseq [m meshes
+                :let [[r g b a] (:color (:mesh m))]]
+          (GL20/glUniform4f color-loc r g b a)
+          (GL30/glBindVertexArray (:vao m))
+          (GL11/glDrawElements GL11/GL_TRIANGLES (:indices-count m) GL11/GL_UNSIGNED_INT 0)))
 
       (GL30/glBindVertexArray 0)
       (GL20/glUseProgram 0))
@@ -86,7 +86,7 @@
   (GLFW/glfwWindowHint GLFW/GLFW_CONTEXT_VERSION_MINOR 5)
   (GLFW/glfwWindowHint GLFW/GLFW_OPENGL_PROFILE GLFW/GLFW_OPENGL_CORE_PROFILE)
 
-  (let [window (GLFW/glfwCreateWindow 1900 #_300 1100 "NOL" MemoryUtil/NULL MemoryUtil/NULL)]
+  (let [window (GLFW/glfwCreateWindow 960 #_1900 300 #_1100 "NOL" MemoryUtil/NULL MemoryUtil/NULL)]
     (when (= window MemoryUtil/NULL)
       (GLFW/glfwTerminate)
       (throw (RuntimeException. "Failed to create window")))
@@ -136,7 +136,12 @@
 
 (defn extract-mesh [^AIScene scene idx]
   (let [meshes (.mMeshes scene)]
-    (let [mesh (AIMesh/create (.get meshes idx))
+    (let [mesh (AIMesh/create (long (.get meshes idx)))
+          mat-idx (.mMaterialIndex mesh)
+          mat-ptr ^long (.get (.mMaterials scene) mat-idx)
+          material (AIMaterial/create (long mat-ptr))
+          mat-color (AIColor4D/create)
+          _ (Assimp/aiGetMaterialColor material Assimp/AI_MATKEY_COLOR_DIFFUSE 0 0 ^AIColor4D mat-color)
           verts (.mVertices mesh)
           n (.mNumVertices mesh)
           vert-arr (float-array (* 3 n))
@@ -154,7 +159,11 @@
           (aset idx-arr (+ (* i 3) 0) (.get idxs 0))
           (aset idx-arr (+ (* i 3) 1) (.get idxs 1))
           (aset idx-arr (+ (* i 3) 2) (.get idxs 2))))
-      {:verts vert-arr :indices idx-arr :mat-idx (.mMaterialIndex mesh)})))
+      {:verts vert-arr :indices idx-arr :mat-idx (.mMaterialIndex mesh)
+       :color (let [color [(.r mat-color) (.g mat-color) (.b mat-color) (.a mat-color)]]
+                (if (= color [1.0 1.0 1.0 1.0])
+                  [(rand) (rand) (rand) 1.0]
+                  color))})))
 
 (defn load-model [path]
   (let [flags (bit-or Assimp/aiProcess_Triangulate
@@ -181,10 +190,13 @@
                       (GL45/glVertexArrayAttribBinding vao 0 0)
                       (GL45/glEnableVertexArrayAttrib vao 0)
                       {:vbo vbo :vao vao :ebo ebo
+                       :mesh mesh
                        :indices-count (alength (:indices mesh))})))))
 
   (with-gl
     (GL11/glClearColor 0.392 0.584 0.929 1.0))
+  (with-gl
+    (GL11/glClearColor 0.0 0.0 0.0 1.0))
 
   (with-gl
     (GL45/glNamedBufferSubData (:vbo @state) 0 ^floats (float-array [ 0.0   0.5 0.0