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85 lines
2.9 KiB
C++
85 lines
2.9 KiB
C++
//
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// TextureBuilder.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 08/03/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#ifndef Outputs_CRT_Internals_TextureBuilder_hpp
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#define Outputs_CRT_Internals_TextureBuilder_hpp
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#include <cstdint>
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#include <functional>
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#include <memory>
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#include <vector>
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#include "OpenGL.hpp"
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#include "CRTConstants.hpp"
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namespace Outputs {
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namespace CRT {
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/*!
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Owns an OpenGL texture resource and provides mechanisms to fill it from bottom left to top right
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with runs of data, ensuring each run is neighboured immediately to the left and right by copies of its
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first and last pixels.
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*/
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class TextureBuilder {
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public:
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/// Constructs an instance of InputTextureBuilder that contains a texture of colour depth @c bytes_per_pixel;
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/// this creates a new texture and binds it to the current active texture unit.
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TextureBuilder(size_t bytes_per_pixel, GLenum texture_unit);
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virtual ~TextureBuilder();
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/// Finds the first available space of at least @c required_length pixels in size. Calls must be paired off
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/// with calls to @c reduce_previous_allocation_to.
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/// @returns a pointer to the allocated space if any was available; @c nullptr otherwise.
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uint8_t *allocate_write_area(size_t required_length);
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/// Announces that the owner is finished with the region created by the most recent @c allocate_write_area
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/// and indicates that its actual final size was @c actual_length.
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void reduce_previous_allocation_to(size_t actual_length);
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/// @returns @c true if all future calls to @c allocate_write_area will fail on account of the input texture
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/// being full; @c false if calls may succeed.
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bool is_full();
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/// Updates the currently-bound texture with all new data provided since the last @c submit.
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void submit();
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struct WriteArea {
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uint16_t x, y, length;
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};
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/// Finalises all write areas allocated since the last call to @c flush. Only finalised areas will be
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/// submitted upon the next @c submit. The supplied function will be called with a list of write areas
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/// allocated, indicating their final resting locations and their lengths.
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void flush(const std::function<void(const std::vector<WriteArea> &write_areas, size_t count)> &);
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private:
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// the buffer size
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size_t bytes_per_pixel_;
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// the buffer
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std::vector<uint8_t> image_;
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GLuint texture_name_;
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// the current list of write areas
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std::vector<WriteArea> write_areas_;
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size_t number_of_write_areas_;
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bool is_full_;
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bool did_submit_;
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bool has_write_area_;
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inline uint8_t *pointer_to_location(uint16_t x, uint16_t y);
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// Usually: the start position for the current batch of write areas.
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// Caveat: reset to the origin upon a submit. So used in comparison by flush to
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// determine whether the current batch of write areas needs to be relocated.
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uint16_t write_areas_start_x_, write_areas_start_y_;
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};
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}
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}
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#endif /* Outputs_CRT_Internals_TextureBuilder_hpp */
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