💿🐜 Antkeeper source code
https://antkeeper.com
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294 lines
10 KiB
294 lines
10 KiB
/*
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* Copyright (C) 2021 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 "renderer/passes/shadow-map-pass.hpp"
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#include "resources/resource-manager.hpp"
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#include "rasterizer/rasterizer.hpp"
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#include "rasterizer/framebuffer.hpp"
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#include "rasterizer/shader-program.hpp"
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#include "rasterizer/shader-input.hpp"
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#include "rasterizer/drawing-mode.hpp"
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#include "renderer/render-context.hpp"
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#include "renderer/material.hpp"
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#include "renderer/material-flags.hpp"
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#include "scene/camera.hpp"
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#include "scene/light.hpp"
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#include "geometry/view-frustum.hpp"
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#include "geometry/aabb.hpp"
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#include "configuration.hpp"
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#include "math/math.hpp"
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#include <cmath>
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#include <glad/glad.h>
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static bool operation_compare(const render_operation& a, const render_operation& b);
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void shadow_map_pass::distribute_frustum_splits(float* split_distances, std::size_t split_count, float split_scheme, float near, float far)
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{
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// Calculate split distances
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for (std::size_t i = 0; i < split_count; ++i)
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{
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float part = static_cast<float>(i + 1) / static_cast<float>(split_count + 1);
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// Calculate uniform split distance
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float uniform_split_distance = near + (far - near) * part;
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// Calculate logarithmic split distance
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float log_split_distance = near * std::pow(far / near, part);
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// Interpolate between uniform and logarithmic split distances
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split_distances[i] = log_split_distance * split_scheme + uniform_split_distance * (1.0f - split_scheme);
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}
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}
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shadow_map_pass::shadow_map_pass(::rasterizer* rasterizer, const ::framebuffer* framebuffer, resource_manager* resource_manager):
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render_pass(rasterizer, framebuffer),
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split_scheme_weight(0.5f),
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light(nullptr)
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{
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// Load skinned shader program
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unskinned_shader_program = resource_manager->load<::shader_program>("depth-unskinned.glsl");
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unskinned_model_view_projection_input = unskinned_shader_program->get_input("model_view_projection");
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// Load unskinned shader program
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skinned_shader_program = resource_manager->load<::shader_program>("depth-skinned.glsl");
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skinned_model_view_projection_input = skinned_shader_program->get_input("model_view_projection");
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// Calculate bias-tile matrices
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float4x4 bias_matrix = math::translate(math::identity4x4<float>, float3{0.5f, 0.5f, 0.5f}) * math::scale(math::identity4x4<float>, float3{0.5f, 0.5f, 0.5f});
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float4x4 tile_scale = math::scale(math::identity4x4<float>, float3{0.5f, 0.5f, 1.0f});
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for (int i = 0; i < 4; ++i)
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{
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float x = static_cast<float>(i % 2) * 0.5f;
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float y = static_cast<float>(i / 2) * 0.5f;
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float4x4 tile_matrix = math::translate(math::identity4x4<float>, float3{x, y, 0.0f}) * tile_scale;
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bias_tile_matrices[i] = tile_matrix * bias_matrix;
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}
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}
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shadow_map_pass::~shadow_map_pass()
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{}
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void shadow_map_pass::render(render_context* context) const
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{
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// Abort if no directional light was set
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if (!light)
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{
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return;
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}
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rasterizer->use_framebuffer(*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_LESS);
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glDepthMask(GL_TRUE);
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// Disable face culling
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glDisable(GL_CULL_FACE);
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// For half-z buffer
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//glDepthRange(-1.0f, 1.0f);
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// Get camera
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const scene::camera& camera = *context->camera;
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// Calculate distances to the depth clipping planes of each frustum split
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float clip_near = camera.get_clip_near_tween().interpolate(context->alpha);
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float clip_far = camera.get_clip_far_tween().interpolate(context->alpha);
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split_distances[0] = clip_near;
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split_distances[4] = clip_far;
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distribute_frustum_splits(&split_distances[1], 3, split_scheme_weight, clip_near, clip_far);
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// Calculate viewports for each shadow map
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const int shadow_map_resolution = std::get<0>(framebuffer->get_dimensions()) / 2;
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float4 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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float4& viewport = shadow_map_viewports[i];
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viewport[0] = static_cast<float>(x * shadow_map_resolution);
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viewport[1] = static_cast<float>(y * shadow_map_resolution);
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viewport[2] = static_cast<float>(shadow_map_resolution);
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viewport[3] = static_cast<float>(shadow_map_resolution);
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}
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// Calculate a view-projection matrix from the directional light's transform
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math::transform<float> light_transform = light->get_transform_tween().interpolate(context->alpha);
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float3 forward = light_transform.rotation * global_forward;
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float3 up = light_transform.rotation * global_up;
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float4x4 light_view = math::look_at(light_transform.translation, light_transform.translation + forward, up);
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float4x4 light_projection = math::ortho_half_z(-1.0f, 1.0f, -1.0f, 1.0f, -1.0f, 1.0f);
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float4x4 light_view_projection = light_projection * light_view;
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// Get the camera's view matrix
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float4x4 camera_view = camera.get_view_tween().interpolate(context->alpha);
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float4x4 crop_matrix;
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float4x4 cropped_view_projection;
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float4x4 model_view_projection;
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// Sort render operations
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context->operations.sort(operation_compare);
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shader_program* active_shader_program = nullptr;
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for (int i = 0; i < 4; ++i)
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{
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// Set viewport for this shadow map
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const float4& viewport = shadow_map_viewports[i];
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rasterizer->set_viewport(viewport[0], viewport[1], viewport[2], viewport[3]);
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// Calculate projection matrix for view camera subfrustum
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const float subfrustum_near = split_distances[i];
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const float subfrustum_far = split_distances[i + 1];
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float4x4 subfrustum_projection = math::perspective_half_z(camera.get_fov(), camera.get_aspect_ratio(), subfrustum_near, subfrustum_far);
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// Calculate view camera subfrustum
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view_frustum<float> subfrustum(subfrustum_projection * camera_view);
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// Create AABB containing the view camera subfrustum corners
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const std::array<vector<float, 3>, 8>& subfrustum_corners = subfrustum.get_corners();
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aabb<float> subfrustum_aabb = {subfrustum_corners[0], subfrustum_corners[0]};
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for (int j = 1; j < 8; ++j)
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{
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for (int k = 0; k < 3; ++k)
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{
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subfrustum_aabb.min_point[k] = std::min<float>(subfrustum_aabb.min_point[k], subfrustum_corners[j][k]);
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subfrustum_aabb.max_point[k] = std::max<float>(subfrustum_aabb.max_point[k], subfrustum_corners[j][k]);
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}
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}
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// Transform subfrustum AABB into the light clip space
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aabb<float> cropping_bounds = aabb<float>::transform(subfrustum_aabb, light_view_projection);
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// Calculate scale
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float3 scale;
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scale.x = 2.0f / (cropping_bounds.max_point.x - cropping_bounds.min_point.x);
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scale.y = 2.0f / (cropping_bounds.max_point.y - cropping_bounds.min_point.y);
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scale.z = 1.0f / (cropping_bounds.max_point.z - cropping_bounds.min_point.z);
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//scale.z = 2.0f / (cropping_bounds.max_point.z - cropping_bounds.min_point.z);
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// Quantize scale
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float scale_quantizer = 64.0f;
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scale.x = 1.0f / std::ceil(1.0f / scale.x * scale_quantizer) * scale_quantizer;
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scale.y = 1.0f / std::ceil(1.0f / scale.y * scale_quantizer) * scale_quantizer;
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// Calculate offset
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float3 offset;
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offset.x = (cropping_bounds.max_point.x + cropping_bounds.min_point.x) * scale.x * -0.5f;
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offset.y = (cropping_bounds.max_point.y + cropping_bounds.min_point.y) * scale.y * -0.5f;
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offset.z = -cropping_bounds.min_point.z * scale.z;
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//offset.z = (cropping_bounds.max_point.z + cropping_bounds.min_point.z) * scale.z * -0.5f;
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// Quantize offset
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float half_shadow_map_resolution = static_cast<float>(shadow_map_resolution) * 0.5f;
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offset.x = std::ceil(offset.x * half_shadow_map_resolution) / half_shadow_map_resolution;
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offset.y = std::ceil(offset.y * half_shadow_map_resolution) / half_shadow_map_resolution;
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// Crop the light view-projection matrix
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crop_matrix = math::translate(math::identity4x4<float>, offset) * math::scale(math::identity4x4<float>, scale);
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cropped_view_projection = crop_matrix * light_view_projection;
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// Calculate shadow matrix
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shadow_matrices[i] = bias_tile_matrices[i] * cropped_view_projection;
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for (const render_operation& operation: context->operations)
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{
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// Skip materials which don't cast shadows
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const ::material* material = operation.material;
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if (material && (material->get_flags() & MATERIAL_FLAG_NOT_SHADOW_CASTER))
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{
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continue;
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}
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// Switch shader programs if necessary
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::shader_program* shader_program = (operation.pose != nullptr) ? skinned_shader_program : unskinned_shader_program;
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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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model_view_projection = cropped_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)
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{
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unskinned_model_view_projection_input->upload(model_view_projection);
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}
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else if (active_shader_program == skinned_shader_program)
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{
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skinned_model_view_projection_input->upload(model_view_projection);
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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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void shadow_map_pass::set_split_scheme_weight(float weight)
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{
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split_scheme_weight = weight;
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}
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void shadow_map_pass::set_light(const scene::directional_light* light)
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{
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this->light = light;
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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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// Determine transparency
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bool skinned_a = (a.pose != nullptr);
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bool skinned_b = (b.pose != nullptr);
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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 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 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 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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