From 9aaf7a8057255d751b066fd21076f64e25987c3d Mon Sep 17 00:00:00 2001
From: 630Studios <StrikeBackStudios@gmail.com>
Date: Fri, 16 Jul 2021 15:14:13 -0500
Subject: [PATCH] GenMeshTangents Fix (#1877)

* GenMeshTangents Fix

* GenMeshTangents Fix - Comment Update

* GenMeshTangents Fix - Comment Update final

* Code Style Changes

* Code Style Changes Final
---
 src/models.c | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/src/models.c b/src/models.c
index be1516c1..917e1c21 100644
--- a/src/models.c
+++ b/src/models.c
@@ -2652,11 +2652,20 @@ BoundingBox GetMeshBoundingBox(Mesh mesh)
 // Implementation base don: https://answers.unity.com/questions/7789/calculating-tangents-vector4.html
 void GenMeshTangents(Mesh *mesh)
 {
-    if (mesh->tangents == NULL) mesh->tangents = (float *)RL_MALLOC(mesh->vertexCount*4*sizeof(float));
-    else TRACELOG(LOG_WARNING, "MESH: Tangents data already available, re-writting");
 
-    Vector3 *tan1 = (Vector3 *)RL_MALLOC(mesh->vertexCount*sizeof(Vector3));
-    Vector3 *tan2 = (Vector3 *)RL_MALLOC(mesh->vertexCount*sizeof(Vector3));
+    if (mesh->tangents == NULL)
+    {
+        mesh->tangents = (float*)RL_MALLOC(mesh->vertexCount*4*sizeof(float));
+    }
+	else
+	{
+        rlUnloadVertexBuffer(mesh->vboId[SHADER_LOC_VERTEX_TANGENT]);
+        RL_FREE(mesh->tangents);
+        mesh->tangents = (float*)RL_MALLOC(mesh->vertexCount*4*sizeof(float));
+    }
+
+    Vector3* tan1 = (Vector3*)RL_MALLOC(mesh->vertexCount*sizeof(Vector3));
+    Vector3* tan2 = (Vector3*)RL_MALLOC(mesh->vertexCount*sizeof(Vector3));
 
     for (int i = 0; i < mesh->vertexCount; i += 3)
     {
@@ -2683,7 +2692,7 @@ void GenMeshTangents(Mesh *mesh)
         float t2 = uv3.y - uv1.y;
 
         float div = s1*t2 - s2*t1;
-        float r = (div == 0.0f)? 0.0f : 1.0f/div;
+        float r = (div == 0.0f) ? 0.0f : 1.0f/div;
 
         Vector3 sdir = { (t2*x1 - t1*x2)*r, (t2*y1 - t1*y2)*r, (t2*z1 - t1*z2)*r };
         Vector3 tdir = { (s1*x2 - s2*x1)*r, (s1*y2 - s2*y1)*r, (s1*z2 - s2*z1)*r };
@@ -2704,20 +2713,20 @@ void GenMeshTangents(Mesh *mesh)
         Vector3 tangent = tan1[i];
 
         // TODO: Review, not sure if tangent computation is right, just used reference proposed maths...
-    #if defined(COMPUTE_TANGENTS_METHOD_01)
+	#if defined(COMPUTE_TANGENTS_METHOD_01)
         Vector3 tmp = Vector3Subtract(tangent, Vector3Scale(normal, Vector3DotProduct(normal, tangent)));
         tmp = Vector3Normalize(tmp);
         mesh->tangents[i*4 + 0] = tmp.x;
         mesh->tangents[i*4 + 1] = tmp.y;
         mesh->tangents[i*4 + 2] = tmp.z;
         mesh->tangents[i*4 + 3] = 1.0f;
-    #else
+	#else
         Vector3OrthoNormalize(&normal, &tangent);
         mesh->tangents[i*4 + 0] = tangent.x;
         mesh->tangents[i*4 + 1] = tangent.y;
         mesh->tangents[i*4 + 2] = tangent.z;
-        mesh->tangents[i*4 + 3] = (Vector3DotProduct(Vector3CrossProduct(normal, tangent), tan2[i]) < 0.0f)? -1.0f : 1.0f;
-    #endif
+        mesh->tangents[i*4 + 3] = (Vector3DotProduct(Vector3CrossProduct(normal, tangent), tan2[i]) < 0.0f) ? -1.0f : 1.0f;
+	#endif
     }
 
     RL_FREE(tan1);
@@ -2725,6 +2734,12 @@ void GenMeshTangents(Mesh *mesh)
 
     // Load a new tangent attributes buffer
     mesh->vboId[SHADER_LOC_VERTEX_TANGENT] = rlLoadVertexBuffer(mesh->tangents, mesh->vertexCount*4*sizeof(float), false);
+    
+    
+    rlEnableVertexArray(mesh->vaoId);
+    rlSetVertexAttribute(4, 4, RL_FLOAT, 0, 0, 0);
+    rlEnableVertexAttribute(4);
+    rlDisableVertexArray();
 
     TRACELOG(LOG_INFO, "MESH: Tangents data computed for provided mesh");
 }