Add explicit support for requesting no mipmaps.

[movit] / effect.h

diff --git a/effect.h b/effect.h
index a1852fc12e09f9a1abf454d0167241b26c7d3e1a..79e4020fc0fa1bd3f188ba2aa2b5fd1f131a88c5 100644 (file)
--- a/effect.h
+++ b/effect.h
@@ -169,12 +169,37 @@ public:
        // either will be fine.
        virtual bool needs_texture_bounce() const { return false; }
 
-       // 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;
+               }
+       }
 
        // Whether there is a direct correspondence between input and output
        // texels. Specifically, the effect must not: