💿🐜 Antkeeper source code
https://antkeeper.com
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511 lines
17 KiB
511 lines
17 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/stages/cascaded-shadow-map-stage.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/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 <engine/geom/primitives/view-frustum.hpp>
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#include <cmath>
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#include <glad/glad.h>
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#include <algorithm>
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#include <execution>
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#include <mutex>
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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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cascaded_shadow_map_stage::cascaded_shadow_map_stage(gl::rasterizer& rasterizer, ::resource_manager& resource_manager):
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m_rasterizer(&rasterizer)
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{
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// Init shader template definitions
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m_shader_template_definitions["VERTEX_POSITION"] = std::to_string(vertex_attribute::position);
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m_shader_template_definitions["VERTEX_UV"] = std::to_string(vertex_attribute::uv);
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m_shader_template_definitions["VERTEX_NORMAL"] = std::to_string(vertex_attribute::normal);
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m_shader_template_definitions["VERTEX_TANGENT"] = std::to_string(vertex_attribute::tangent);
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m_shader_template_definitions["VERTEX_COLOR"] = std::to_string(vertex_attribute::color);
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m_shader_template_definitions["VERTEX_BONE_INDEX"] = std::to_string(vertex_attribute::bone_index);
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m_shader_template_definitions["VERTEX_BONE_WEIGHT"] = std::to_string(vertex_attribute::bone_weight);
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m_shader_template_definitions["VERTEX_BONE_WEIGHT"] = std::to_string(vertex_attribute::bone_weight);
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m_shader_template_definitions["MAX_BONE_COUNT"] = std::to_string(m_max_bone_count);
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// Static mesh shader
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{
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// Load static mesh shader template
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m_static_mesh_shader_template = resource_manager.load<gl::shader_template>("shadow-cascade-static-mesh.glsl");
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// Build static mesh shader program
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rebuild_static_mesh_shader_program();
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}
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// Skeletal mesh shader
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{
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// Load skeletal mesh shader template
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m_skeletal_mesh_shader_template = resource_manager.load<gl::shader_template>("shadow-cascade-skeletal-mesh.glsl");
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// Build static mesh shader program
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rebuild_skeletal_mesh_shader_program();
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}
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}
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void cascaded_shadow_map_stage::execute(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 lights that don't share a common layer with the camera
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if (!(directional_light.get_layer_mask() & ctx.camera->get_layer_mask()))
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{
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return;
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}
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// Ignore improperly-configured lights
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if (!directional_light.get_shadow_framebuffer())
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{
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continue;
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}
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// Render shadow atlas
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render_shadow_atlas(ctx, directional_light);
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}
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ctx.operations.clear();
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}
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void cascaded_shadow_map_stage::set_max_bone_count(std::size_t bone_count)
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{
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if (m_max_bone_count != bone_count)
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{
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m_max_bone_count = bone_count;
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// Update max bone count shader template definition
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m_shader_template_definitions["MAX_BONE_COUNT"] = std::to_string(m_max_bone_count);
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// Rebuild skeletal mesh shader
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rebuild_skeletal_mesh_shader_program();
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}
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}
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void cascaded_shadow_map_stage::queue(render::context& ctx, scene::directional_light& light, const math::fmat4& light_view_projection)
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{
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// Clear pre-existing render operations
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ctx.operations.clear();
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// Combine camera and light layer masks
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const auto camera_light_layer_mask = ctx.camera->get_layer_mask() & light.get_layer_mask();
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// Build light view frustum from light view projection matrix
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const geom::view_frustum<float> light_view_frustum(light_view_projection);
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// Tests whether a box is completely outside a plane
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auto box_outside_plane = [](const geom::box<float>& box, const geom::plane<float>& plane) -> bool
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{
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const math::fvec3 p =
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{
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(plane.normal.x() > 0.0f) ? box.max.x() : box.min.x(),
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(plane.normal.y() > 0.0f) ? box.max.y() : box.min.y(),
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(plane.normal.z() > 0.0f) ? box.max.z() : box.min.z()
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};
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return plane.distance(p) < 0.0f;
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};
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// For each object in the scene collection
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const auto& objects = ctx.collection->get_objects();
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std::for_each
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(
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std::execution::seq,
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std::begin(objects),
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std::end(objects),
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[&](scene::object_base* object)
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{
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// Cull object if it doesn't share a common layer with the camera and light
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if (!(object->get_layer_mask() & camera_light_layer_mask))
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{
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return;
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}
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// Ignore cameras and lights
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if (object->get_object_type_id() == scene::camera::object_type_id || object->get_object_type_id() == scene::light::object_type_id)
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{
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return;
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}
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// Cull object if it's outside of the light view frustum (excluding near plane [reverse-z, so far=near])
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const auto& object_bounds = object->get_bounds();
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if (box_outside_plane(object_bounds, light_view_frustum.left()) ||
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box_outside_plane(object_bounds, light_view_frustum.right()) ||
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box_outside_plane(object_bounds, light_view_frustum.bottom()) ||
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box_outside_plane(object_bounds, light_view_frustum.top()) ||
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box_outside_plane(object_bounds, light_view_frustum.near()))
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{
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return;
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}
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// Add object render operations to render context
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object->render(ctx);
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}
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);
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}
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void cascaded_shadow_map_stage::render_shadow_atlas(render::context& ctx, scene::directional_light& light)
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{
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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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// Disable depth clipping (enable "pancaking")
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glEnable(GL_DEPTH_CLAMP);
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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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// Bind and clear shadow atlas framebuffer
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m_rasterizer->use_framebuffer(*light.get_shadow_framebuffer());
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m_rasterizer->clear_framebuffer(false, true, false);
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// Get camera
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const scene::camera& camera = *ctx.camera;
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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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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] = light.get_shadow_max_distance();
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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 split distances
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const float linear_distance = math::lerp(camera.get_clip_near(), camera.get_clip_near() + light.get_shadow_max_distance(), weight);
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const float log_distance = math::log_lerp(camera.get_clip_near(), camera.get_clip_near() + light.get_shadow_max_distance(), weight);
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// Interpolate between linear and logarithmic split 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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// Determine resolution of shadow atlas and cascades
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const auto atlas_resolution = static_cast<int>(light.get_shadow_framebuffer()->get_depth_attachment()->get_width());
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const auto cascade_resolution = atlas_resolution >> 1;
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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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for (unsigned int i = 0; i < cascade_count; ++i)
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{
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// Get distances to near and far clipping planes of camera subfrustum
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const auto subfrustum_near = i ? cascade_distances[i - 1] : camera.get_clip_near();
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const auto subfrustum_far = cascade_distances[i];
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// Find centroid of camera subfrustum
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const auto subfrustum_centroid = camera.get_translation() + camera.get_forward() * ((subfrustum_near + subfrustum_far) * 0.5f);
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// Construct light view matrix
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const auto light_view = math::look_at_rh(subfrustum_centroid, subfrustum_centroid + light.get_direction(), light.get_rotation() * math::fvec3{0, 1, 0});
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// Construct subfrustum inverse view-projection matrix
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const auto [subfrustum_projection, subfrustum_inv_projection] = math::perspective_half_z_inv(camera.get_vertical_fov(), camera.get_aspect_ratio(), subfrustum_far, subfrustum_near);
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const auto subfrustum_inv_view_projection = camera.get_inv_view() * subfrustum_inv_projection;
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// Construct matrix which transforms clip space coordinates to light view space
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const auto ndc_to_light_view = light_view * subfrustum_inv_view_projection;
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// Construct AABB containing subfrustum corners in light view space
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geom::box<float> light_projection_bounds = {math::fvec3::infinity(), -math::fvec3::infinity()};
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for (std::size_t j = 0; j < 8; ++j)
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{
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// Reverse half z clip-space coordinates of a cube
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constexpr math::fvec4 ndc_cube[8] =
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{
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{-1, -1, 1, 1}, // NBL
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{ 1, -1, 1, 1}, // NBR
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{-1, 1, 1, 1}, // NTL
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{ 1, 1, 1, 1}, // NTR
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{-1, -1, 0, 1}, // FBL
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{ 1, -1, 0, 1}, // FBR
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{-1, 1, 0, 1}, // FTL
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{ 1, 1, 0, 1} // FTR
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};
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// Find light view space coordinates of subfrustum corner
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const auto corner = ndc_to_light_view * ndc_cube[j];
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// Expand light projection bounds to contain corner
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light_projection_bounds.extend(math::fvec3(corner) / corner[3]);
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}
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// Construct light projection matrix
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const auto light_projection = math::ortho_half_z
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(
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light_projection_bounds.min.x(), light_projection_bounds.max.x(),
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light_projection_bounds.min.y(), light_projection_bounds.max.y(),
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-light_projection_bounds.min.z(), -light_projection_bounds.max.z()
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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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const auto light_view_translation = math::fvec4(subfrustum_centroid);
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const auto light_view_rotation = math::fmat4(math::fmat3(light_view));
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// Update view-space to cascade texture-space transformation matrix
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{
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const auto vs_subfrustum_centroid = math::fvec3{0.0f, 0.0f, ((subfrustum_near + subfrustum_far) * -0.5f)};
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const auto vs_light_direction = light.get_direction() * camera.get_rotation();
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const auto vs_light_up = (light.get_rotation() * math::fvec3{0, 1, 0}) * camera.get_rotation();
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const auto vs_light_view = math::look_at_rh(vs_subfrustum_centroid, vs_subfrustum_centroid + vs_light_direction, vs_light_up);
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const auto vs_light_view_projection = light_projection * vs_light_view;
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cascade_matrices[i] = light.get_shadow_scale_bias_matrices()[i] * vs_light_view_projection;
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}
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// Queue render operations
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queue(ctx, light, light_view_projection);
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if (ctx.operations.empty())
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{
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continue;
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}
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// Set viewport for this cascade
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const auto viewport_x = static_cast<int>(i % 2) * cascade_resolution;
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const auto viewport_y = static_cast<int>(i >> 1) * cascade_resolution;
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m_rasterizer->set_viewport(viewport_x, viewport_y, cascade_resolution, cascade_resolution);
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// Render geometry
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for (const render::operation* operation: ctx.operations)
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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()) ? m_static_mesh_shader_program.get() : m_skeletal_mesh_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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m_rasterizer->use_program(*active_shader_program);
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}
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// Calculate model-view-projection matrix
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// @see Persson, E., & Studios, A. (2012). Creating vast game worlds: Experiences from avalanche studios. In ACM SIGGRAPH 2012 Talks (pp. 1-1).
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auto model_view = operation->transform;
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model_view[3] -= light_view_translation;
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model_view = light_view_rotation * model_view;
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const auto model_view_projection = light_projection * model_view;
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// Upload operation-dependent parameters to shader program
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if (active_shader_program == m_static_mesh_shader_program.get())
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{
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m_static_mesh_model_view_projection_var->update(model_view_projection);
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}
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else if (active_shader_program == m_skeletal_mesh_shader_program.get())
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{
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m_skeletal_mesh_model_view_projection_var->update(model_view_projection);
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m_skeletal_mesh_matrix_palette_var->update(operation->matrix_palette);
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}
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// Draw geometry
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m_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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// Re-enable depth clipping (disable "pancaking")
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glDisable(GL_DEPTH_CLAMP);
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}
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void cascaded_shadow_map_stage::rebuild_static_mesh_shader_program()
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{
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m_static_mesh_shader_program = m_static_mesh_shader_template->build(m_shader_template_definitions);
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if (!m_static_mesh_shader_program->linked())
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{
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debug::log::error("Failed to build cascaded shadow map shader program for static meshes: {}", m_static_mesh_shader_program->info());
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debug::log::warning("{}", m_static_mesh_shader_template->configure(gl::shader_stage::vertex));
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m_static_mesh_model_view_projection_var = nullptr;
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}
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else
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{
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m_static_mesh_model_view_projection_var = m_static_mesh_shader_program->variable("model_view_projection");
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}
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}
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void cascaded_shadow_map_stage::rebuild_skeletal_mesh_shader_program()
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{
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m_skeletal_mesh_shader_program = m_skeletal_mesh_shader_template->build(m_shader_template_definitions);
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if (!m_skeletal_mesh_shader_program->linked())
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{
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debug::log::error("Failed to build cascaded shadow map shader program for skeletal meshes: {}", m_skeletal_mesh_shader_program->info());
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debug::log::warning("{}", m_skeletal_mesh_shader_template->configure(gl::shader_stage::vertex));
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m_skeletal_mesh_model_view_projection_var = nullptr;
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m_skeletal_mesh_matrix_palette_var = nullptr;
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}
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else
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{
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m_skeletal_mesh_model_view_projection_var = m_skeletal_mesh_shader_program->variable("model_view_projection");
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m_skeletal_mesh_matrix_palette_var = m_skeletal_mesh_shader_program->variable("matrix_palette");
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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
|
|
return (a->vertex_array < b->vertex_array);
|
|
}
|
|
else
|
|
{
|
|
// A is two-sided, B is one-sided. Render B first
|
|
return false;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (two_sided_b)
|
|
{
|
|
// A is one-sided, B is two-sided. Render A first
|
|
return true;
|
|
}
|
|
else
|
|
{
|
|
// A and B are both one-sided, sort by VAO
|
|
return (a->vertex_array < b->vertex_array);
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
// A is skinned, B is unskinned. Render B first
|
|
return false;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (skinned_b)
|
|
{
|
|
// A is unskinned, B is skinned. Render A first
|
|
return true;
|
|
}
|
|
else
|
|
{
|
|
// A and B are both unskinned, sort by two-sided
|
|
if (two_sided_a)
|
|
{
|
|
if (two_sided_b)
|
|
{
|
|
// A and B are both two-sided, sort by VAO
|
|
return (a->vertex_array < b->vertex_array);
|
|
}
|
|
else
|
|
{
|
|
// A is two-sided, B is one-sided. Render B first
|
|
return false;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (two_sided_b)
|
|
{
|
|
// A is one-sided, B is two-sided. Render A first
|
|
return true;
|
|
}
|
|
else
|
|
{
|
|
// A and B are both one-sided, sort by VAO
|
|
return (a->vertex_array < b->vertex_array);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
} // namespace render
|