- // Whether this effect expects mipmaps or not. If you set this to
- // true, you will be sampling with bilinear filtering; if not,
- // you could be sampling with simple linear filtering and no mipmaps
- // (although there is no guarantee; if a different effect in the chain
- // needs mipmaps, you will also get them).
- virtual bool needs_mipmaps() const { return false; }
+ // Whether this effect expects mipmaps or not.
+ enum MipmapRequirements {
+ // If chosen, you will be sampling with bilinear filtering,
+ // ie. the closest mipmap will be chosen, and then there will be
+ // bilinear interpolation inside it (GL_LINEAR_MIPMAP_NEAREST).
+ NEEDS_MIPMAPS,
+
+ // Whether the effect doesn't really care whether input textures
+ // are with or without mipmaps. You could get the same effect
+ // as NEEDS_MIPMAPS or CANNOT_ACCEPT_MIPMAPS; normally, you won't
+ // get them, but if a different effect in the same phase needs mipmaps,
+ // you will also get them.
+ DOES_NOT_NEED_MIPMAPS,
+
+ // The opposite of NEEDS_MIPMAPS; you will always be sampling from
+ // the most detailed mip level (GL_LINEAR). Effects with NEEDS_MIPMAPS
+ // and CANNOT_ACCEPT_MIPMAPS can not coexist within the same phase;
+ // such phases will be split.
+ //
+ // This is the only choice that makes sense for a compute shader,
+ // given that it doesn't have screen-space derivatives and thus
+ // always will sample the most detailed mip level.
+ CANNOT_ACCEPT_MIPMAPS,
+ };
+ virtual MipmapRequirements needs_mipmaps() const {
+ if (is_compute_shader()) {
+ return CANNOT_ACCEPT_MIPMAPS;
+ } else {
+ return DOES_NOT_NEED_MIPMAPS;
+ }
+ }