[rmodels] Improve OBJ vertex data precision and lower memory usage by ExportMesh() (#4496)

* increased vertex data precision to match blender exports

* modified memory allocation to better fit higher precision data

* now accounting for newline characters during allocation

* now accounting for potentially higher vertex counts

* removed unnecessary final newline

src/rmodels.c

@@ -1943,13 +1943,14 @@ bool ExportMesh(Mesh mesh, const char *fileName)
     if (IsFileExtension(fileName, ".obj"))
     {
         // Estimated data size, it should be enough...
-        int dataSize = mesh.vertexCount*(int)strlen("v 0000.00f 0000.00f 0000.00f") +
-                       mesh.vertexCount*(int)strlen("vt 0.000f 0.00f") +
-                       mesh.vertexCount*(int)strlen("vn 0.000f 0.00f 0.00f") +
-                       mesh.triangleCount*(int)strlen("f 00000/00000/00000 00000/00000/00000 00000/00000/00000");
+        int vc = mesh.vertexCount;
+        int dataSize = vc*(int)strlen("v -0000.000000f -0000.000000f -0000.000000f\n") +
+                       vc*(int)strlen("vt -0.000000f -0.000000f\n") +
+                       vc*(int)strlen("vn -0.0000f -0.0000f -0.0000f\n") +
+                       mesh.triangleCount*snprintf(NULL, 0, "f %i/%i/%i %i/%i/%i %i/%i/%i\n", vc, vc, vc, vc, vc, vc, vc, vc, vc);
 
         // NOTE: Text data buffer size is estimated considering mesh data size
-        char *txtData = (char *)RL_CALLOC(dataSize*2 + 2000, sizeof(char));
+        char *txtData = (char *)RL_CALLOC(dataSize + 1000, sizeof(char));
 
         int byteCount = 0;
         byteCount += sprintf(txtData + byteCount, "# //////////////////////////////////////////////////////////////////////////////////\n");
@@ -1969,17 +1970,17 @@ bool ExportMesh(Mesh mesh, const char *fileName)
 
         for (int i = 0, v = 0; i < mesh.vertexCount; i++, v += 3)
         {
-            byteCount += sprintf(txtData + byteCount, "v %.2f %.2f %.2f\n", mesh.vertices[v], mesh.vertices[v + 1], mesh.vertices[v + 2]);
+            byteCount += sprintf(txtData + byteCount, "v %.6f %.6f %.6f\n", mesh.vertices[v], mesh.vertices[v + 1], mesh.vertices[v + 2]);
         }
 
         for (int i = 0, v = 0; i < mesh.vertexCount; i++, v += 2)
         {
-            byteCount += sprintf(txtData + byteCount, "vt %.3f %.3f\n", mesh.texcoords[v], mesh.texcoords[v + 1]);
+            byteCount += sprintf(txtData + byteCount, "vt %.6f %.6f\n", mesh.texcoords[v], mesh.texcoords[v + 1]);
         }
 
         for (int i = 0, v = 0; i < mesh.vertexCount; i++, v += 3)
         {
-            byteCount += sprintf(txtData + byteCount, "vn %.3f %.3f %.3f\n", mesh.normals[v], mesh.normals[v + 1], mesh.normals[v + 2]);
+            byteCount += sprintf(txtData + byteCount, "vn %.4f %.4f %.4f\n", mesh.normals[v], mesh.normals[v + 1], mesh.normals[v + 2]);
         }
 
         if (mesh.indices != NULL)
@@ -2000,8 +2001,6 @@ bool ExportMesh(Mesh mesh, const char *fileName)
             }
         }
 
-        byteCount += sprintf(txtData + byteCount, "\n");
-
         // NOTE: Text data length exported is determined by '\0' (NULL) character
         success = SaveFileText(fileName, txtData);