Sokol sg image desc sokol:sokol.sg_image_desc Struct sg_image_desc# Fields _end_canary _start_canary border_color content d3d11_shader_resource_view d3d11_texture gl_textures height label mag_filter max_anisotropy max_lod min_filter min_lod mtl_textures num_mipmaps num_slices pixel_format render_target sample_count type usage wgpu_texture width wrap_u wrap_v wrap_w