+// A compute shader implementation of DeinterlaceEffect. It saves a bunch of loads
+// since it can share them between neighboring pixels (and also does not need
+// texture bounce), so it has the potential to be faster, although exactly how
+// much depends on your chain and other factors. DeinterlaceEffect will
+// automatically become a proxy to DeinterlaceComputeEffect if your system
+// supports compute shaders.
+class DeinterlaceComputeEffect : public Effect {
+public:
+ DeinterlaceComputeEffect();
+ virtual std::string effect_type_id() const { return "DeinterlaceComputeEffect"; }
+ std::string output_fragment_shader();
+
+ void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
+
+ virtual unsigned num_inputs() const { return 5; }
+ virtual bool changes_output_size() const { return true; }
+ virtual bool is_compute_shader() const { return true; }
+ virtual void get_compute_dimensions(unsigned output_width, unsigned output_height,
+ unsigned *x, unsigned *y, unsigned *z) const;
+
+ virtual AlphaHandling alpha_handling() const { return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK; }
+
+ virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height);
+ virtual void get_output_size(unsigned *width, unsigned *height,
+ unsigned *virtual_width, unsigned *virtual_height) const;
+
+ enum FieldPosition { TOP = 0, BOTTOM = 1 };
+
+private:
+ unsigned widths[5], heights[5];
+
+ // See file-level comment for explanation of this option.
+ bool enable_spatial_interlacing_check;
+
+ // Which field the current input (the middle one) is.
+ FieldPosition current_field_position;
+
+ // Offset for one pixel in the horizontal and verticla direction (1/width, 1/height).
+ float inv_width, inv_height;
+
+ // For evaluating the low-pass filter (in the current field). Four taps.
+ float current_field_vertical_offset;
+};
+