💿🐜 Antkeeper source code
https://antkeeper.com
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391 lines
13 KiB
391 lines
13 KiB
/*
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* Copyright (C) 2023 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <engine/render/passes/shadow-map-pass.hpp>
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#include <engine/resources/resource-manager.hpp>
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#include <engine/gl/rasterizer.hpp>
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#include <engine/gl/framebuffer.hpp>
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#include <engine/gl/shader-program.hpp>
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#include <engine/gl/drawing-mode.hpp>
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#include <engine/render/context.hpp>
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#include <engine/render/material.hpp>
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#include <engine/render/vertex-attribute.hpp>
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#include <engine/gl/shader-template.hpp>
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#include <engine/scene/camera.hpp>
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#include <engine/scene/collection.hpp>
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#include <engine/scene/light.hpp>
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#include <engine/geom/primitives/view-frustum.hpp>
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#include <engine/math/interpolation.hpp>
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#include <engine/math/vector.hpp>
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#include <engine/math/matrix.hpp>
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#include <engine/math/quaternion.hpp>
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#include <engine/math/projection.hpp>
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#include <cmath>
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#include <glad/glad.h>
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#include <execution>
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namespace render {
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static bool operation_compare(const render::operation* a, const render::operation* b);
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shadow_map_pass::shadow_map_pass(gl::rasterizer* rasterizer, resource_manager* resource_manager):
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pass(rasterizer, nullptr)
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{
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std::unordered_map<std::string, std::string> definitions;
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definitions["VERTEX_POSITION"] = std::to_string(vertex_attribute::position);
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definitions["VERTEX_UV"] = std::to_string(vertex_attribute::uv);
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definitions["VERTEX_NORMAL"] = std::to_string(vertex_attribute::normal);
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definitions["VERTEX_TANGENT"] = std::to_string(vertex_attribute::tangent);
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definitions["VERTEX_COLOR"] = std::to_string(vertex_attribute::color);
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definitions["VERTEX_BONE_INDEX"] = std::to_string(vertex_attribute::bone_index);
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definitions["VERTEX_BONE_WEIGHT"] = std::to_string(vertex_attribute::bone_weight);
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definitions["VERTEX_BONE_WEIGHT"] = std::to_string(vertex_attribute::bone_weight);
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definitions["MAX_BONE_COUNT"] = std::to_string(64);
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// Load unskinned shader template
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auto unskinned_shader_template = resource_manager->load<gl::shader_template>("depth-unskinned.glsl");
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// Build unskinned shader program
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unskinned_shader_program = unskinned_shader_template->build(definitions);
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if (!unskinned_shader_program->linked())
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{
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debug::log::error("Failed to build unskinned shadow map shader program: {}", unskinned_shader_program->info());
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debug::log::warning("{}", unskinned_shader_template->configure(gl::shader_stage::vertex));
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}
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unskinned_model_view_projection_var = unskinned_shader_program->variable("model_view_projection");
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// Load skinned shader template
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auto skinned_shader_template = resource_manager->load<gl::shader_template>("depth-skinned.glsl");
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// Build skinned shader program
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skinned_shader_program = skinned_shader_template->build(definitions);
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if (!skinned_shader_program->linked())
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{
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debug::log::error("Failed to build skinned shadow map shader program: {}", skinned_shader_program->info());
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debug::log::warning("{}", skinned_shader_template->configure(gl::shader_stage::vertex));
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}
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skinned_model_view_projection_var = skinned_shader_program->variable("model_view_projection");
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skinned_matrix_palette_var = skinned_shader_program->variable("matrix_palette");
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}
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void shadow_map_pass::render(render::context& ctx)
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{
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// For each light
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const auto& lights = ctx.collection->get_objects(scene::light::object_type_id);
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for (scene::object_base* object: lights)
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{
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// Ignore non-directional lights
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auto& light = static_cast<scene::light&>(*object);
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if (light.get_light_type() != scene::light_type::directional)
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{
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continue;
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}
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// Ignore non-shadow casters
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auto& directional_light = static_cast<scene::directional_light&>(light);
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if (!directional_light.is_shadow_caster())
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{
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continue;
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}
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// Ignore improperly-configured lights
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if (!directional_light.get_shadow_framebuffer() || !directional_light.get_shadow_cascade_count())
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{
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continue;
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}
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// Render cascaded shadow maps
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render_csm(directional_light, ctx);
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}
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}
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void shadow_map_pass::render_csm(scene::directional_light& light, render::context& ctx)
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{
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// Get light layer mask
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const auto light_layer_mask = light.get_layer_mask();
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if (!(light_layer_mask & ctx.camera->get_layer_mask()))
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{
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return;
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}
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rasterizer->use_framebuffer(*light.get_shadow_framebuffer());
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// Disable blending
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glDisable(GL_BLEND);
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// Enable depth testing
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glEnable(GL_DEPTH_TEST);
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glDepthFunc(GL_GREATER);
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glDepthMask(GL_TRUE);
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// Enable back-face culling
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glEnable(GL_CULL_FACE);
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glCullFace(GL_BACK);
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bool two_sided = false;
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// Get camera
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const scene::camera& camera = *ctx.camera;
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// Calculate distance to shadow cascade depth clipping planes
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const float shadow_clip_far = math::lerp(camera.get_clip_near(), camera.get_clip_far(), light.get_shadow_cascade_coverage());
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// Get light shadow cascade distances and matrices
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const auto cascade_count = light.get_shadow_cascade_count();
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const auto cascade_distances = light.get_shadow_cascade_distances();
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const auto cascade_matrices = light.get_shadow_cascade_matrices();
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// Calculate cascade far clipping plane distances
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cascade_distances[cascade_count - 1] = shadow_clip_far;
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for (unsigned int i = 0; i < cascade_count - 1; ++i)
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{
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const float weight = static_cast<float>(i + 1) / static_cast<float>(cascade_count);
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// Calculate linear and logarithmic distribution distances
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const float linear_distance = math::lerp(camera.get_clip_near(), shadow_clip_far, weight);
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const float log_distance = math::log_lerp(camera.get_clip_near(), shadow_clip_far, weight);
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// Interpolate between linear and logarithmic distribution distances
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cascade_distances[i] = math::lerp(linear_distance, log_distance, light.get_shadow_cascade_distribution());
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}
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// Calculate viewports for each shadow map
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const int shadow_map_resolution = static_cast<int>(light.get_shadow_framebuffer()->get_depth_attachment()->get_width());
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const int cascade_resolution = shadow_map_resolution >> 1;
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math::ivec4 shadow_map_viewports[4];
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for (int i = 0; i < 4; ++i)
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{
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int x = i % 2;
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int y = i / 2;
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math::ivec4& viewport = shadow_map_viewports[i];
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viewport[0] = x * cascade_resolution;
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viewport[1] = y * cascade_resolution;
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viewport[2] = cascade_resolution;
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viewport[3] = cascade_resolution;
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}
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// Sort render operations
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std::sort(std::execution::par_unseq, ctx.operations.begin(), ctx.operations.end(), operation_compare);
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gl::shader_program* active_shader_program = nullptr;
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// Precalculate frustum minimal bounding sphere terms
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const auto k = std::sqrt(1.0f + camera.get_aspect_ratio() * camera.get_aspect_ratio()) * std::tan(camera.get_vertical_fov() * 0.5f);
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const auto k2 = k * k;
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const auto k4 = k2 * k2;
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for (unsigned int i = 0; i < cascade_count; ++i)
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{
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// Set viewport for this shadow map
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const math::ivec4& viewport = shadow_map_viewports[i];
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rasterizer->set_viewport(viewport[0], viewport[1], viewport[2], viewport[3]);
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// Find minimal bounding sphere of subfrustum in view-space
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// @see https://lxjk.github.io/2017/04/15/Calculate-Minimal-Bounding-Sphere-of-Frustum.html
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geom::sphere<float> subfrustum_bounds;
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{
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// Get subfrustum near and far distances
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const auto n = (i) ? cascade_distances[i - 1] : camera.get_clip_near();
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const auto f = cascade_distances[i];
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if (k2 >= (f - n) / (f + n))
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{
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subfrustum_bounds.center = {0, 0, -f};
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subfrustum_bounds.radius = f * k;
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}
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else
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{
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subfrustum_bounds.center = {0, 0, -0.5f * (f + n) * (1.0f + k2)};
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subfrustum_bounds.radius = 0.5f * std::sqrt((k4 + 2.0f * k2 + 1.0f) * (f * f + n * n) + 2.0f * f * (k4 - 1.0f) * n);
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}
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}
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// Transform subfrustum bounds into world-space
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subfrustum_bounds.center = camera.get_translation() + camera.get_rotation() * subfrustum_bounds.center;
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// Discretize view-space subfrustum bounds
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const auto texel_scale = static_cast<float>(cascade_resolution) / (subfrustum_bounds.radius * 2.0f);
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subfrustum_bounds.center = math::conjugate(light.get_rotation()) * subfrustum_bounds.center;
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subfrustum_bounds.center = math::floor(subfrustum_bounds.center * texel_scale) / texel_scale;
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subfrustum_bounds.center = light.get_rotation() * subfrustum_bounds.center;
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// Construct light view matrix
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const auto light_view = math::look_at_rh(subfrustum_bounds.center, subfrustum_bounds.center + light.get_direction(), light.get_rotation() * math::fvec3{0, 1, 0});
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// Construct light projection matrix (reversed depth)
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const auto light_projection = math::ortho_half_z
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(
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-subfrustum_bounds.radius, subfrustum_bounds.radius,
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-subfrustum_bounds.radius, subfrustum_bounds.radius,
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subfrustum_bounds.radius, -subfrustum_bounds.radius
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);
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// Construct light view-projection matrix
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const auto light_view_projection = light_projection * light_view;
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// Update world-space to cascade texture-space transformation matrix
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cascade_matrices[i] = light.get_shadow_scale_bias_matrices()[i] * light_view_projection;
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for (const render::operation* operation: ctx.operations)
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{
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// Skip operations which don't share any layers with the shadow-casting light
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if (!(operation->layer_mask & light_layer_mask))
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{
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continue;
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}
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const render::material* material = operation->material.get();
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if (material)
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{
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// Skip materials which don't cast shadows
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if (material->get_shadow_mode() == material_shadow_mode::none)
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{
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continue;
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}
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if (material->is_two_sided() != two_sided)
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{
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if (material->is_two_sided())
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{
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glDisable(GL_CULL_FACE);
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}
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else
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{
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glEnable(GL_CULL_FACE);
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}
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two_sided = material->is_two_sided();
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}
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}
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// Switch shader programs if necessary
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gl::shader_program* shader_program = (operation->matrix_palette.empty()) ? unskinned_shader_program.get() : skinned_shader_program.get();
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if (active_shader_program != shader_program)
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{
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active_shader_program = shader_program;
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rasterizer->use_program(*active_shader_program);
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}
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// Calculate model-view-projection matrix
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math::fmat4 model_view_projection = light_view_projection * operation->transform;
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// Upload operation-dependent parameters to shader program
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if (active_shader_program == unskinned_shader_program.get())
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{
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unskinned_model_view_projection_var->update(model_view_projection);
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}
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else if (active_shader_program == skinned_shader_program.get())
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{
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skinned_model_view_projection_var->update(model_view_projection);
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skinned_matrix_palette_var->update(operation->matrix_palette);
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}
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// Draw geometry
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rasterizer->draw_arrays(*operation->vertex_array, operation->drawing_mode, operation->start_index, operation->index_count);
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}
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}
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}
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bool operation_compare(const render::operation* a, const render::operation* b)
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{
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const bool skinned_a = !a->matrix_palette.empty();
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const bool skinned_b = !b->matrix_palette.empty();
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const bool two_sided_a = (a->material) ? a->material->is_two_sided() : false;
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const bool two_sided_b = (b->material) ? b->material->is_two_sided() : false;
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if (skinned_a)
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{
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if (skinned_b)
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{
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// A and B are both skinned, sort by two-sided
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if (two_sided_a)
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{
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if (two_sided_b)
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{
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// A and B are both two-sided, sort by VAO
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return (a->vertex_array < b->vertex_array);
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}
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else
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{
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// A is two-sided, B is one-sided. Render B first
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return false;
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}
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}
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else
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{
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if (two_sided_b)
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{
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// A is one-sided, B is two-sided. Render A first
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return true;
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}
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else
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{
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// A and B are both one-sided, sort by VAO
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return (a->vertex_array < b->vertex_array);
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}
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}
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}
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else
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{
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// A is skinned, B is unskinned. Render B first
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return false;
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}
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}
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else
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{
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if (skinned_b)
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{
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// A is unskinned, B is skinned. Render A first
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return true;
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}
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else
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{
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// A and B are both unskinned, sort by two-sided
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if (two_sided_a)
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{
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if (two_sided_b)
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{
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// A and B are both two-sided, sort by VAO
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return (a->vertex_array < b->vertex_array);
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}
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else
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{
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// A is two-sided, B is one-sided. Render B first
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return false;
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}
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}
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else
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{
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if (two_sided_b)
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{
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// A is one-sided, B is two-sided. Render A first
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return true;
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}
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else
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{
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// A and B are both one-sided, sort by VAO
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return (a->vertex_array < b->vertex_array);
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}
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}
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}
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}
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}
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} // namespace render
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