Merge pull request #518 from Th3T3chn0G1t/master

demo/backend: Fixed UBSan trip in GLFW OpenGL3

demo/glfw_opengl3/nuklear_glfw_gl3.h

@@ -240,7 +240,7 @@ nk_glfw3_render(struct nk_glfw* glfw, enum nk_anti_aliasing AA, int max_vertex_b
         /* convert from command queue into draw list and draw to screen */
         const struct nk_draw_command *cmd;
         void *vertices, *elements;
-        const nk_draw_index *offset = NULL;
+        nk_size offset = 0;
 
         /* allocate vertex and element buffer */
         glBindVertexArray(dev->vao);
@@ -292,8 +292,8 @@ nk_glfw3_render(struct nk_glfw* glfw, enum nk_anti_aliasing AA, int max_vertex_b
                 (GLint)((glfw->height - (GLint)(cmd->clip_rect.y + cmd->clip_rect.h)) * glfw->fb_scale.y),
                 (GLint)(cmd->clip_rect.w * glfw->fb_scale.x),
                 (GLint)(cmd->clip_rect.h * glfw->fb_scale.y));
-            glDrawElements(GL_TRIANGLES, (GLsizei)cmd->elem_count, GL_UNSIGNED_SHORT, offset);
-            offset += cmd->elem_count;
+            glDrawElements(GL_TRIANGLES, (GLsizei)cmd->elem_count, GL_UNSIGNED_SHORT, (const void*) offset);
+            offset += cmd->elem_count * sizeof(nk_draw_index);
         }
         nk_clear(&glfw->ctx);
         nk_buffer_clear(&dev->cmds);