1 #ifndef _MOVIT_RESAMPLE_EFFECT_H
2 #define _MOVIT_RESAMPLE_EFFECT_H 1
4 // High-quality image resizing, either up or down.
6 // The default scaling offered by the GPU (and as used in ResizeEffect)
7 // is bilinear (optionally mipmapped), which is not the highest-quality
8 // choice, especially for upscaling. ResampleEffect offers the three-lobed
9 // Lanczos kernel, which is among the most popular choices in image
10 // processing. While it does have its weaknesses, in particular a certain
11 // ringing/sharpening effect with artifacts that accumulate over several
12 // consecutive resizings, it is generally regarded as the best tradeoff.
14 // Works in two passes; first horizontal, then vertical (ResampleEffect,
15 // which is what the user is intended to use, instantiates two copies of
16 // SingleResamplePassEffect behind the scenes).
29 class SingleResamplePassEffect;
31 class ResampleEffect : public Effect {
35 virtual std::string effect_type_id() const { return "ResampleEffect"; }
37 // We want this for the same reason as ResizeEffect; we could end up scaling
39 virtual bool needs_texture_bounce() const { return true; }
40 virtual bool needs_srgb_primaries() const { return false; }
42 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height);
44 virtual std::string output_fragment_shader() {
47 virtual void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num) {
51 virtual void rewrite_graph(EffectChain *graph, Node *self);
52 virtual bool set_float(const std::string &key, float value);
56 void update_offset_and_zoom();
58 SingleResamplePassEffect *hpass, *vpass;
59 int input_width, input_height, output_width, output_height;
61 float offset_x, offset_y;
63 float zoom_center_x, zoom_center_y;
66 class SingleResamplePassEffect : public Effect {
68 // If parent is non-NULL, calls to inform_input_size will be forwarded,
69 // so that it can inform both passes about the right input and output
71 SingleResamplePassEffect(ResampleEffect *parent);
72 ~SingleResamplePassEffect();
73 virtual std::string effect_type_id() const { return "SingleResamplePassEffect"; }
75 std::string output_fragment_shader();
77 virtual bool needs_texture_bounce() const { return true; }
78 virtual bool needs_srgb_primaries() const { return false; }
79 virtual AlphaHandling alpha_handling() const { return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK; }
81 virtual void inform_added(EffectChain *chain) { this->chain = chain; }
82 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height) {
84 parent->inform_input_size(input_num, width, height);
87 virtual bool changes_output_size() const { return true; }
88 virtual bool sets_virtual_output_size() const { return false; }
90 virtual void get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const {
91 *virtual_width = *width = this->output_width;
92 *virtual_height = *height = this->output_height;
95 void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
97 enum Direction { HORIZONTAL = 0, VERTICAL = 1 };
100 void update_texture(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
102 ResampleEffect *parent;
106 GLint uniform_sample_tex;
107 float uniform_num_loops, uniform_slice_height, uniform_sample_x_scale, uniform_sample_x_offset;
108 float uniform_whole_pixel_offset;
109 int uniform_num_samples;
111 int input_width, input_height, output_width, output_height;
113 int last_input_width, last_input_height, last_output_width, last_output_height;
114 float last_offset, last_zoom;
115 int src_bilinear_samples, num_loops;
117 int last_texture_width, last_texture_height;
118 GLuint last_texture_internal_format;
123 #endif // !defined(_MOVIT_RESAMPLE_EFFECT_H)