math.go (1155B)
1 // Copyright 2014 Hajime Hoshi 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package graphics 16 17 // InternalImageSize returns a nearest appropriate size as an internal image. 18 func InternalImageSize(x int) int { 19 // minInternalImageSize is the minimum size of internal images (texture/framebuffer). 20 // 21 // For example, the image size less than 15 is not supported on some iOS devices. 22 // See also: https://stackoverflow.com/questions/15935651 23 const minInternalImageSize = 16 24 25 if x <= 0 { 26 panic("graphics: x must be positive") 27 } 28 if x < minInternalImageSize { 29 return minInternalImageSize 30 } 31 r := 1 32 for r < x { 33 r <<= 1 34 } 35 return r 36 }