GenMeshTangents Fix

src/models.c

@@ -2652,8 +2652,30 @@ 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");
+     * Added - 7/16/2021 - Jason Penick
+     * Check and see if the mesh already has tangents.
+     * If the mesh does not have tangents we can simply alloate the space for the data.
+     * 
+     * If the mesh did have tangents, we can not readily depend on the current vertexCount
+     * to be the actual length of the existing tangent data as the mesh vertices could
+     * have been altered and now contain less or more vertices which would result in
+     * either updating to few tangents, or attempting to over-run the space allocated
+     * for the tangents previously. In order to account for this the memory for the
+     * current tangent data must be freed as well as the previously assigned VertexBuffer,
+     * and then we can recreate the tangent data with the new size designated by vertexCount
+     * and create a new VertexBuffer to assign for the tangents.
+     * 
+     */
+    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));
@@ -2726,6 +2748,16 @@ 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);
     
+    /*
+     * Added - 7/16/2021 - Jason Penick
+     * Upate the tangets on the GPU.
+     * Issue raised by Kenneth on discord.
+     */
+    rlEnableVertexArray(mesh->vaoId);
+    rlSetVertexAttribute(4, 4, RL_FLOAT, 0, 0, 0);
+    rlEnableVertexAttribute(4);
+    rlDisableVertexArray();
+
     TRACELOG(LOG_INFO, "MESH: Tangents data computed for provided mesh");
 }