Hard-assert on something that has bitten me too many times now.

[movit] / padding_effect.h

diff --git a/padding_effect.h b/padding_effect.h
index 9a32abbe41c343661abdef7bfa9d0e289a48d85e..d922944f81703f5847cc21e36778bdecfba59e42 100644 (file)
--- a/padding_effect.h
+++ b/padding_effect.h
@@ -5,18 +5,34 @@
 // (although the latter is implemented slightly less efficiently, and you cannot both
 // pad and crop in the same effect).
 //
-// The source image is cut off at the texel borders (so there is no interpolation
-// outside them), and then given a user-specific color; by default, full transparent.
+// The source image is cut off at the texture border, and then given a user-specific color;
+// by default, full transparent. You can give a fractional border size (non-integral
+// "top" or "left" offset) if you wish, which will give you linear interpolation of
+// both pixel data of and the border. Furthermore, you can offset where the border falls
+// by using the "border_offset_{top,bottom,left,right}" settings; this is particularly
+// useful if you use ResampleEffect earlier in the chain for high-quality fractional-pixel
+// translation and just want PaddingEffect to get the border right.
 //
 // The border color is taken to be in linear gamma, sRGB, with premultiplied alpha.
 // You may not change it after calling finalize(), since that could change the
 // graph (need_linear_light() etc. depend on the border color you choose).
+//
+// IntegralPaddingEffect is like PaddingEffect, except that "top" and "left" parameters
+// are int parameters instead of float. This allows it to guarantee one-to-one sampling,
+// which can speed up processing by allowing more effect passes to be collapsed.
+// border_offset_* are still allowed to be float, although you should beware that if
+// you set e.g. border_offset_top to a negative value, you will be sampling outside
+// the edge and will read data that is undefined in one-to-one-mode (could be
+// edge repeat, could be something else). With regular PaddingEffect, such samples
+// are guaranteed to be edge repeat.
 
-#include <GL/glew.h>
+#include <epoxy/gl.h>
 #include <string>
 
 #include "effect.h"
 
+namespace movit {
+
 class PaddingEffect : public Effect {
 public:
        PaddingEffect();
@@ -29,6 +45,7 @@ public:
        virtual AlphaHandling alpha_handling() const;
        
        virtual bool changes_output_size() const { return true; }
+       virtual bool sets_virtual_output_size() const { return false; }
        virtual void get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const;
        virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height);
 
@@ -37,6 +54,22 @@ private:
        int input_width, input_height;
        int output_width, output_height;
        float top, left;
+       float border_offset_top, border_offset_left;
+       float border_offset_bottom, border_offset_right;
+       float uniform_offset[2], uniform_scale[2];
+       float uniform_normalized_coords_to_texels[2];
+       float uniform_offset_bottomleft[2], uniform_offset_topright[2];
+};
+
+class IntegralPaddingEffect : public PaddingEffect {
+public:
+       IntegralPaddingEffect();
+       virtual std::string effect_type_id() const { return "IntegralPaddingEffect"; }
+       virtual bool one_to_one_sampling() const { return true; }
+       virtual bool set_int(const std::string&, int value);
+       virtual bool set_float(const std::string &key, float value);
 };
 
+}  // namespace movit
+
 #endif // !defined(_MOVIT_PADDING_EFFECT_H)