graphics.cpp

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/*
 * Copyright (C) 2023  Christopher J. Howard
 *
 * This file is part of Antkeeper source code.
 *
 * Antkeeper source code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Antkeeper source code is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Antkeeper source code.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "game/graphics.hpp"
#include <engine/config.hpp>
#include <engine/debug/log.hpp>
#include <engine/gl/framebuffer.hpp>
#include <engine/gl/texture.hpp>
#include <engine/render/passes/bloom-pass.hpp>
#include <engine/render/passes/final-pass.hpp>
#include <engine/render/passes/resample-pass.hpp>
#include <engine/render/passes/sky-pass.hpp>
#include <engine/render/passes/material-pass.hpp>
#include <chrono>
#include <filesystem>
#include <format>
#include <glad/gl.h>
#include <stb/stb_image_write.h>
#include <thread>
 
namespace graphics {
 
static void reroute_framebuffers(::game& ctx);
 
static void rebuild_hdr_framebuffer(::game& ctx)
{
    // Construct HDR framebuffer sampler
    auto hdr_sampler = std::make_shared<gl::sampler>
    (
        gl::sampler_filter::linear,
        gl::sampler_filter::linear,
        gl::sampler_mipmap_mode::linear,
        gl::sampler_address_mode::clamp_to_edge,
        gl::sampler_address_mode::clamp_to_edge
    );
    
    // Construct HDR framebuffer color texture
    ctx.hdr_color_texture = std::make_shared<gl::texture_2d>
    (
        std::make_shared<gl::image_view_2d>
        (
            std::make_shared<gl::image_2d>
            (
                gl::format::r32g32b32_sfloat,
                ctx.render_resolution.x(),
                ctx.render_resolution.y()
            )
        ),
        hdr_sampler
    );
    
    // Construct HDR framebuffer depth texture
    ctx.hdr_depth_texture = std::make_shared<gl::texture_2d>
    (
        std::make_shared<gl::image_view_2d>
        (
            std::make_shared<gl::image_2d>
            (
                gl::format::d32_sfloat_s8_uint,
                ctx.render_resolution.x(),
                ctx.render_resolution.y()
            )
        ),
        hdr_sampler
    );
    
    // Construct HDR framebuffer
    const gl::framebuffer_attachment hdr_attachments[2] =
    {
        {
            gl::color_attachment_bit,
            ctx.hdr_color_texture->get_image_view(),
            0
        },
        {
            gl::depth_stencil_attachment_bits,
            ctx.hdr_depth_texture->get_image_view(),
            0
        }
    };
    ctx.hdr_framebuffer = std::make_shared<gl::framebuffer>(hdr_attachments, ctx.render_resolution.x(), ctx.render_resolution.y());
}
 
static void rebuild_ldr_framebuffers(::game& ctx)
{
    auto ldr_sampler = std::make_shared<gl::sampler>
    (
        gl::sampler_filter::linear,
        gl::sampler_filter::linear,
        gl::sampler_mipmap_mode::linear,
        gl::sampler_address_mode::clamp_to_edge,
        gl::sampler_address_mode::clamp_to_edge
    );
    
    // Construct LDR framebuffer A color texture
    ctx.ldr_color_texture_a = std::make_shared<gl::texture_2d>
    (
        std::make_shared<gl::image_view_2d>
        (
            std::make_shared<gl::image_2d>
            (
                gl::format::r8g8b8_unorm,
                ctx.render_resolution.x(),
                ctx.render_resolution.y()
            )
        ),
        ldr_sampler
    );
    
    // Construct LDR framebuffer A
    const gl::framebuffer_attachment ldr_attachments_a[1] =
    {
        {
            gl::color_attachment_bit,
            ctx.ldr_color_texture_a->get_image_view(),
            0
        }
    };
    ctx.ldr_framebuffer_a = std::make_shared<gl::framebuffer>(ldr_attachments_a, ctx.render_resolution.x(), ctx.render_resolution.y());
    
    // Construct LDR framebuffer B color texture
    ctx.ldr_color_texture_b = std::make_shared<gl::texture_2d>
    (
        std::make_shared<gl::image_view_2d>
        (
            std::make_shared<gl::image_2d>
            (
                gl::format::r8g8b8_unorm,
                ctx.render_resolution.x(),
                ctx.render_resolution.y()
            )
        ),
        ldr_sampler
    );
    
    // Construct LDR framebuffer B
    const gl::framebuffer_attachment ldr_attachments_b[1] =
    {
        {
            gl::color_attachment_bit,
            ctx.ldr_color_texture_b->get_image_view(),
            0
        }
    };
    ctx.ldr_framebuffer_b = std::make_shared<gl::framebuffer>(ldr_attachments_b, ctx.render_resolution.x(), ctx.render_resolution.y());
}
 
void rebuild_shadow_framebuffer(::game& ctx)
{
    // Construct shadow map sampler
    auto shadow_sampler = std::make_shared<gl::sampler>
    (
        gl::sampler_filter::linear,
        gl::sampler_filter::linear,
        gl::sampler_mipmap_mode::linear,
        gl::sampler_address_mode::clamp_to_border,
        gl::sampler_address_mode::clamp_to_border,
        gl::sampler_address_mode::clamp_to_border,
        0.0f,
        0.0f,
        true,
        gl::compare_op::greater,
        -1000.0f,
        1000.0f,
        std::array<float, 4>{0.0f, 0.0f, 0.0f, 0.0f}
    );
    
    // Construct shadow map framebuffer depth texture
    ctx.shadow_map_depth_texture = std::make_shared<gl::texture_2d>
    (
        std::make_shared<gl::image_view_2d>
        (
            std::make_shared<gl::image_2d>
            (
                gl::format::d32_sfloat,
                ctx.shadow_map_resolution,
                ctx.shadow_map_resolution
            )
        ),
        shadow_sampler
    );
    
    // Construct shadow map framebuffer
    const gl::framebuffer_attachment shadow_map_attachments[1] =
    {
        {
            gl::depth_attachment_bit,
            ctx.shadow_map_depth_texture->get_image_view(),
            0
        }
    };
    ctx.shadow_map_framebuffer = std::make_shared<gl::framebuffer>(shadow_map_attachments, ctx.shadow_map_resolution, ctx.shadow_map_resolution);
}
 
void create_framebuffers(::game& ctx)
{
    debug::log_trace("Creating framebuffers...");
    
    // Calculate render resolution
    const math::ivec2& viewport_size = ctx.window->get_viewport_size();
    ctx.render_resolution = {static_cast<int>(viewport_size.x() * ctx.render_scale + 0.5f), static_cast<int>(viewport_size.y() * ctx.render_scale + 0.5f)};
    
    rebuild_hdr_framebuffer(ctx);
    rebuild_ldr_framebuffers(ctx);
    rebuild_shadow_framebuffer(ctx);
    
    debug::log_trace("Created framebuffers");
}
 
void destroy_framebuffers(::game& ctx)
{
    debug::log_trace("Destroying framebuffers...");
    
    // Delete HDR framebuffer and its attachments
    ctx.hdr_framebuffer.reset();
    ctx.hdr_color_texture.reset();
    ctx.hdr_depth_texture.reset();
    
    // Delete LDR framebuffers and attachments
    ctx.ldr_framebuffer_a.reset();
    ctx.ldr_color_texture_a.reset();
    
    ctx.ldr_framebuffer_b.reset();
    ctx.ldr_color_texture_b.reset();
    
    // Delete shadow map framebuffer and its attachments
    ctx.shadow_map_framebuffer.reset();
    ctx.shadow_map_depth_texture.reset();
    
    debug::log_trace("Destroyed framebuffers");
}
 
void change_render_resolution(::game& ctx, float scale)
{
    // Recalculate render resolution
    const math::ivec2& viewport_size = ctx.window->get_viewport_size();
    const auto render_resolution = math::ivec2{static_cast<int>(viewport_size.x() * scale + 0.5f), static_cast<int>(viewport_size.y() * scale + 0.5f)};
    
    if (ctx.render_resolution == render_resolution)
    {
        return;
    }
    
    debug::log_trace("Changing render resolution to {}...", scale);
    
    // Update render resolution scale
    ctx.render_scale = scale;
    ctx.render_resolution = render_resolution;
    
    rebuild_hdr_framebuffer(ctx);
    rebuild_ldr_framebuffers(ctx);
    
    // Enable or disable resample pass
    if (viewport_size.x() != ctx.render_resolution.x() || viewport_size.y() != ctx.render_resolution.y())
    {
        ctx.resample_pass->set_enabled(true);
        debug::log_debug("Resample pass enabled");
    }
    else
    {
        ctx.resample_pass->set_enabled(false);
        debug::log_debug("Resample pass disabled");
    }
    
    reroute_framebuffers(ctx);
    
    debug::log_trace("Changed render resolution to {}", scale);
}
 
void save_screenshot(::game& ctx)
{
    // Determine timestamped screenshot filename
    const auto time = std::chrono::floor<std::chrono::milliseconds>(std::chrono::system_clock::now());
    const std::string screenshot_filename = std::format("{0}-{1:%Y%m%d}T{1:%H%M%S}Z.png", config::application_name, time);
    
    // Determine path to screenshot file
    std::filesystem::path screenshot_filepath = ctx.screenshots_path / screenshot_filename;
    std::string screenshot_filepath_string = screenshot_filepath.string();
    debug::log_debug("Saving screenshot to \"{}\"...", screenshot_filepath_string);
    
    // Get viewport dimensions
    const auto& viewport_size = ctx.window->get_viewport_size();
    
    // Allocate screenshot pixel data buffer
    std::unique_ptr<std::byte[]> frame = std::make_unique<std::byte[]>(viewport_size.x() * viewport_size.y() * 3);
    
    // Read pixel data from backbuffer into pixel data buffer
    glReadBuffer(GL_BACK);
    glReadPixels(0, 0, viewport_size.x(), viewport_size.y(), GL_RGB, GL_UNSIGNED_BYTE, frame.get());
    
    // Write screenshot file in separate thread
    std::thread
    (
        [frame = std::move(frame), w = viewport_size.x(), h = viewport_size.y(), path = std::move(screenshot_filepath_string)]
        {
            stbi_flip_vertically_on_write(1);
            stbi_write_png(path.c_str(), w, h, 3, frame.get(), w * 3);
            
            debug::log_debug("Saved screenshot to \"{}\"", path);
        }
    ).detach();
}
 
void select_anti_aliasing_method(::game& ctx, render::anti_aliasing_method method)
{
    // Switch AA method
    switch (method)
    {
        // Off
        case render::anti_aliasing_method::none:
            debug::log_debug("Anti-aliasing disabled");
            reroute_framebuffers(ctx);
            break;
        
        // FXAA
        case render::anti_aliasing_method::fxaa:
            debug::log_debug("Anti-aliasing enabled (FXAA)");
            reroute_framebuffers(ctx);
            break;
    }
    
    // Update AA method setting
    ctx.anti_aliasing_method = method;
}
 
void reroute_framebuffers(::game& ctx)
{
    if (ctx.resample_pass->is_enabled())
    {
        ctx.common_final_pass->set_framebuffer(ctx.ldr_framebuffer_a.get());
    }
    else
    {
        ctx.common_final_pass->set_framebuffer(nullptr);
    }
    
    ctx.sky_pass->set_framebuffer(ctx.hdr_framebuffer.get());
    ctx.surface_material_pass->set_framebuffer(ctx.hdr_framebuffer.get());
    ctx.bloom_pass->set_source_texture(ctx.hdr_color_texture);
    ctx.common_final_pass->set_color_texture(ctx.hdr_color_texture);
    ctx.common_final_pass->set_bloom_texture(ctx.bloom_pass->get_bloom_texture());
}
 
} // namespace graphics