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180 lines
6.6 KiB
C++
180 lines
6.6 KiB
C++
//
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// TextureBuilder.cpp
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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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#include "TextureBuilder.hpp"
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#include "CRTOpenGL.hpp"
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#include "OpenGL.hpp"
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#include <cstring>
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using namespace Outputs::CRT;
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namespace {
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const GLint internalFormatForDepth(std::size_t depth) {
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switch(depth) {
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default: return GL_FALSE;
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case 1: return GL_R8UI;
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case 2: return GL_RG8UI;
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case 3: return GL_RGB8UI;
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case 4: return GL_RGBA8UI;
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}
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}
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const GLenum formatForDepth(std::size_t depth) {
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switch(depth) {
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default: return GL_FALSE;
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case 1: return GL_RED_INTEGER;
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case 2: return GL_RG_INTEGER;
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case 3: return GL_RGB_INTEGER;
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case 4: return GL_RGBA_INTEGER;
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}
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}
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}
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TextureBuilder::TextureBuilder(std::size_t bytes_per_pixel, GLenum texture_unit) :
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bytes_per_pixel_(bytes_per_pixel), texture_unit_(texture_unit) {
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image_.resize(bytes_per_pixel * InputBufferBuilderWidth * InputBufferBuilderHeight);
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glGenTextures(1, &texture_name_);
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bind();
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glTexImage2D(GL_TEXTURE_2D, 0, internalFormatForDepth(bytes_per_pixel), InputBufferBuilderWidth, InputBufferBuilderHeight, 0, formatForDepth(bytes_per_pixel), GL_UNSIGNED_BYTE, nullptr);
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}
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TextureBuilder::~TextureBuilder() {
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glDeleteTextures(1, &texture_name_);
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}
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void TextureBuilder::bind() {
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glActiveTexture(texture_unit_);
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glBindTexture(GL_TEXTURE_2D, texture_name_);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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}
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inline uint8_t *TextureBuilder::pointer_to_location(uint16_t x, uint16_t y) {
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return &image_[((y * InputBufferBuilderWidth) + x) * bytes_per_pixel_];
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}
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uint8_t *TextureBuilder::allocate_write_area(std::size_t required_length, std::size_t required_alignment) {
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// Keep a flag to indicate whether the buffer was full at allocate_write_area; if it was then
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// don't return anything now, and decline to act upon follow-up methods. is_full_ may be reset
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// by asynchronous calls to submit. was_full_ will not be touched by it.
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was_full_ = is_full_;
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if(is_full_) return nullptr;
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// If there's not enough space on this line, move to the next. If the next is where the current
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// submission group started, trigger is/was_full_ and return nothing.
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std::size_t alignment_offset = (required_alignment - ((write_areas_start_x_ + 1) % required_alignment)) % required_alignment;
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if(write_areas_start_x_ + required_length + 2 + alignment_offset > InputBufferBuilderWidth) {
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write_areas_start_x_ = 0;
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alignment_offset = required_alignment - 1;
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write_areas_start_y_ = (write_areas_start_y_ + 1) % InputBufferBuilderHeight;
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if(write_areas_start_y_ == first_unsubmitted_y_) {
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was_full_ = is_full_ = true;
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return nullptr;
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}
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}
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// Queue up the latest write area.
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write_areas_start_x_ += static_cast<uint16_t>(alignment_offset);
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write_area_.x = write_areas_start_x_ + 1;
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write_area_.y = write_areas_start_y_;
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write_area_.length = static_cast<uint16_t>(required_length);
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// Return a video pointer.
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return pointer_to_location(write_area_.x, write_area_.y);
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}
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void TextureBuilder::reduce_previous_allocation_to(std::size_t actual_length) {
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// If the previous allocate_write_area declined to act, decline also.
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if(was_full_) return;
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// Update the length of the current write area.
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write_area_.length = static_cast<uint16_t>(actual_length);
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// Bookend the allocation with duplicates of the first and last pixel, to protect
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// against rounding errors when this run is drawn.
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uint8_t *start_pointer = pointer_to_location(write_area_.x, write_area_.y) - bytes_per_pixel_;
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std::memcpy(start_pointer, &start_pointer[bytes_per_pixel_], bytes_per_pixel_);
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std::memcpy(&start_pointer[(actual_length + 1) * bytes_per_pixel_], &start_pointer[actual_length * bytes_per_pixel_], bytes_per_pixel_);
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}
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bool TextureBuilder::retain_latest() {
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// If the previous allocate_write_area declined to act, decline also.
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if(was_full_) return false;
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// Account for the most recently written area as taken.
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write_areas_start_x_ += write_area_.length + 2;
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// Store into the vector directly if there's already room, otherwise grow the vector.
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// Probably I don't need to mess about with this myself; it's unnecessary second-guessing.
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// TODO: profile and prove.
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if(number_of_write_areas_ < write_areas_.size())
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write_areas_[number_of_write_areas_] = write_area_;
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else
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write_areas_.push_back(write_area_);
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number_of_write_areas_++;
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return true;
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}
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void TextureBuilder::discard_latest() {
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if(was_full_) return;
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number_of_write_areas_--;
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}
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bool TextureBuilder::is_full() {
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return is_full_;
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}
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void TextureBuilder::submit() {
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if(write_areas_start_y_ < first_unsubmitted_y_) {
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// A write area start y less than the first line on which submissions began implies it must have wrapped
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// around. So the submission set is everything back to zero before the current write area plus everything
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// from the first unsubmitted y downward.
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uint16_t height = write_areas_start_y_ + (write_areas_start_x_ ? 1 : 0);
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glTexSubImage2D( GL_TEXTURE_2D, 0,
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0, 0,
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InputBufferBuilderWidth, height,
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formatForDepth(bytes_per_pixel_), GL_UNSIGNED_BYTE,
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image_.data());
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glTexSubImage2D( GL_TEXTURE_2D, 0,
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0, first_unsubmitted_y_,
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InputBufferBuilderWidth, InputBufferBuilderHeight - first_unsubmitted_y_,
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formatForDepth(bytes_per_pixel_), GL_UNSIGNED_BYTE,
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image_.data() + first_unsubmitted_y_ * bytes_per_pixel_ * InputBufferBuilderWidth);
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} else {
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// If the current write area start y is after the first unsubmitted line, just submit the region in between.
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uint16_t height = write_areas_start_y_ + (write_areas_start_x_ ? 1 : 0) - first_unsubmitted_y_;
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glTexSubImage2D( GL_TEXTURE_2D, 0,
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0, first_unsubmitted_y_,
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InputBufferBuilderWidth, height,
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formatForDepth(bytes_per_pixel_), GL_UNSIGNED_BYTE,
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image_.data() + first_unsubmitted_y_ * bytes_per_pixel_ * InputBufferBuilderWidth);
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}
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// Update the starting location for the next submission, and mark definitively that the buffer is once again not full.
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first_unsubmitted_y_ = write_areas_start_y_;
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is_full_ = false;
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}
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void TextureBuilder::flush(const std::function<void(const std::vector<WriteArea> &write_areas, std::size_t count)> &function) {
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// Just throw everything currently in the flush queue to the provided function, and note that
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// the queue is now empty.
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if(number_of_write_areas_) {
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function(write_areas_, number_of_write_areas_);
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}
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number_of_write_areas_ = 0;
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}
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