/*
* 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 .
*/
#include
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namespace render {
static bool operation_compare(const render::operation* a, const render::operation* b);
shadow_map_pass::shadow_map_pass(gl::rasterizer* rasterizer, resource_manager* resource_manager):
pass(rasterizer, nullptr)
{
std::unordered_map definitions;
definitions["VERTEX_POSITION"] = std::to_string(vertex_attribute::position);
definitions["VERTEX_UV"] = std::to_string(vertex_attribute::uv);
definitions["VERTEX_NORMAL"] = std::to_string(vertex_attribute::normal);
definitions["VERTEX_TANGENT"] = std::to_string(vertex_attribute::tangent);
definitions["VERTEX_COLOR"] = std::to_string(vertex_attribute::color);
definitions["VERTEX_BONE_INDEX"] = std::to_string(vertex_attribute::bone_index);
definitions["VERTEX_BONE_WEIGHT"] = std::to_string(vertex_attribute::bone_weight);
definitions["VERTEX_BONE_WEIGHT"] = std::to_string(vertex_attribute::bone_weight);
definitions["MAX_BONE_COUNT"] = std::to_string(64);
// Load unskinned shader template
auto unskinned_shader_template = resource_manager->load("depth-unskinned.glsl");
// Build unskinned shader program
unskinned_shader_program = unskinned_shader_template->build(definitions);
if (!unskinned_shader_program->linked())
{
debug::log::error("Failed to build unskinned shadow map shader program: {}", unskinned_shader_program->info());
debug::log::warning("{}", unskinned_shader_template->configure(gl::shader_stage::vertex));
}
unskinned_model_view_projection_var = unskinned_shader_program->variable("model_view_projection");
// Load skinned shader template
auto skinned_shader_template = resource_manager->load("depth-skinned.glsl");
// Build skinned shader program
skinned_shader_program = skinned_shader_template->build(definitions);
if (!skinned_shader_program->linked())
{
debug::log::error("Failed to build skinned shadow map shader program: {}", skinned_shader_program->info());
debug::log::warning("{}", skinned_shader_template->configure(gl::shader_stage::vertex));
}
skinned_model_view_projection_var = skinned_shader_program->variable("model_view_projection");
skinned_matrix_palette_var = skinned_shader_program->variable("matrix_palette");
}
void shadow_map_pass::render(render::context& ctx)
{
// For each light
const auto& lights = ctx.collection->get_objects(scene::light::object_type_id);
for (scene::object_base* object: lights)
{
// Ignore non-directional lights
auto& light = static_cast(*object);
if (light.get_light_type() != scene::light_type::directional)
{
continue;
}
// Ignore non-shadow casters
auto& directional_light = static_cast(light);
if (!directional_light.is_shadow_caster())
{
continue;
}
// Ignore improperly-configured lights
if (!directional_light.get_shadow_framebuffer() || !directional_light.get_shadow_cascade_count())
{
continue;
}
// Render cascaded shadow maps
render_csm(directional_light, ctx);
}
}
void shadow_map_pass::render_csm(scene::directional_light& light, render::context& ctx)
{
// Get light layer mask
const auto light_layer_mask = light.get_layer_mask();
if (!light_layer_mask & ctx.camera->get_layer_mask())
{
return;
}
rasterizer->use_framebuffer(*light.get_shadow_framebuffer());
// Disable blending
glDisable(GL_BLEND);
// Enable depth testing
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_GREATER);
glDepthMask(GL_TRUE);
// Enable back-face culling
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
bool two_sided = false;
// For half-z buffer
glDepthRange(-1.0f, 1.0f);
// Get camera
const scene::camera& camera = *ctx.camera;
// Calculate distance to shadow cascade depth clipping planes
const float shadow_clip_far = math::lerp(camera.get_clip_near(), camera.get_clip_far(), light.get_shadow_cascade_coverage());
// Get light shadow cascade distances and matrices
const auto cascade_count = light.get_shadow_cascade_count();
const auto cascade_distances = light.get_shadow_cascade_distances();
const auto cascade_matrices = light.get_shadow_cascade_matrices();
// Calculate cascade far clipping plane distances
cascade_distances[cascade_count - 1] = shadow_clip_far;
for (unsigned int i = 0; i < cascade_count - 1; ++i)
{
const float weight = static_cast(i + 1) / static_cast(cascade_count);
// Calculate linear and logarithmic distribution distances
const float linear_distance = math::lerp(camera.get_clip_near(), shadow_clip_far, weight);
const float log_distance = math::log_lerp(camera.get_clip_near(), shadow_clip_far, weight);
// Interpolate between linear and logarithmic distribution distances
cascade_distances[i] = math::lerp(linear_distance, log_distance, light.get_shadow_cascade_distribution());
}
// Calculate viewports for each shadow map
const int shadow_map_resolution = static_cast(light.get_shadow_framebuffer()->get_depth_attachment()->get_width());
const int cascade_resolution = shadow_map_resolution >> 1;
math::ivec4 shadow_map_viewports[4];
for (int i = 0; i < 4; ++i)
{
int x = i % 2;
int y = i / 2;
math::ivec4& viewport = shadow_map_viewports[i];
viewport[0] = x * cascade_resolution;
viewport[1] = y * cascade_resolution;
viewport[2] = cascade_resolution;
viewport[3] = cascade_resolution;
}
// Sort render operations
std::sort(std::execution::par_unseq, ctx.operations.begin(), ctx.operations.end(), operation_compare);
gl::shader_program* active_shader_program = nullptr;
// Precalculate frustum minimal bounding sphere terms
const auto k = std::sqrt(1.0f + camera.get_aspect_ratio() * camera.get_aspect_ratio()) * std::tan(camera.get_vertical_fov() * 0.5f);
const auto k2 = k * k;
const auto k4 = k2 * k2;
for (unsigned int i = 0; i < cascade_count; ++i)
{
// Set viewport for this shadow map
const math::ivec4& viewport = shadow_map_viewports[i];
rasterizer->set_viewport(viewport[0], viewport[1], viewport[2], viewport[3]);
// Find minimal bounding sphere of subfrustum in view-space
// @see https://lxjk.github.io/2017/04/15/Calculate-Minimal-Bounding-Sphere-of-Frustum.html
geom::sphere subfrustum_bounds;
{
// Get subfrustum near and far distances
const auto n = (i) ? cascade_distances[i - 1] : camera.get_clip_near();
const auto f = cascade_distances[i];
if (k2 >= (f - n) / (f + n))
{
subfrustum_bounds.center = {0, 0, -f};
subfrustum_bounds.radius = f * k;
}
else
{
subfrustum_bounds.center = {0, 0, -0.5f * (f + n) * (1.0f + k2)};
subfrustum_bounds.radius = 0.5f * std::sqrt((k4 + 2.0f * k2 + 1.0f) * (f * f + n * n) + 2.0f * f * (k4 - 1.0f) * n);
}
}
// Transform subfrustum bounds into world-space
subfrustum_bounds.center = camera.get_translation() + camera.get_rotation() * subfrustum_bounds.center;
// Discretize view-space subfrustum bounds
const auto texel_scale = static_cast(cascade_resolution) / (subfrustum_bounds.radius * 2.0f);
subfrustum_bounds.center = math::conjugate(light.get_rotation()) * subfrustum_bounds.center;
subfrustum_bounds.center = math::floor(subfrustum_bounds.center * texel_scale) / texel_scale;
subfrustum_bounds.center = light.get_rotation() * subfrustum_bounds.center;
// Construct light view matrix
const auto light_view = math::look_at(subfrustum_bounds.center, subfrustum_bounds.center + light.get_direction(), light.get_rotation() * math::fvec3{0, 1, 0});
// Construct light projection matrix (reversed half-z)
const auto light_projection = math::ortho_half_z
(
-subfrustum_bounds.radius, subfrustum_bounds.radius,
-subfrustum_bounds.radius, subfrustum_bounds.radius,
subfrustum_bounds.radius, -subfrustum_bounds.radius
);
// Construct light view-projection matrix
const auto light_view_projection = light_projection * light_view;
// Update world-space to cascade texture-space transformation matrix
cascade_matrices[i] = light.get_shadow_bias_scale_matrices()[i] * light_view_projection;
for (const render::operation* operation: ctx.operations)
{
// Skip operations which don't share any layers with the shadow-casting light
if (!(operation->layer_mask & light_layer_mask))
{
continue;
}
const render::material* material = operation->material.get();
if (material)
{
// Skip materials which don't cast shadows
if (material->get_shadow_mode() == material_shadow_mode::none)
{
continue;
}
if (material->is_two_sided() != two_sided)
{
if (material->is_two_sided())
{
glDisable(GL_CULL_FACE);
}
else
{
glEnable(GL_CULL_FACE);
}
two_sided = material->is_two_sided();
}
}
// Switch shader programs if necessary
gl::shader_program* shader_program = (operation->matrix_palette.empty()) ? unskinned_shader_program.get() : skinned_shader_program.get();
if (active_shader_program != shader_program)
{
active_shader_program = shader_program;
rasterizer->use_program(*active_shader_program);
}
// Calculate model-view-projection matrix
math::fmat4 model_view_projection = light_view_projection * operation->transform;
// Upload operation-dependent parameters to shader program
if (active_shader_program == unskinned_shader_program.get())
{
unskinned_model_view_projection_var->update(model_view_projection);
}
else if (active_shader_program == skinned_shader_program.get())
{
skinned_model_view_projection_var->update(model_view_projection);
skinned_matrix_palette_var->update(operation->matrix_palette);
}
// Draw geometry
rasterizer->draw_arrays(*operation->vertex_array, operation->drawing_mode, operation->start_index, operation->index_count);
}
}
}
bool operation_compare(const render::operation* a, const render::operation* b)
{
const bool skinned_a = !a->matrix_palette.empty();
const bool skinned_b = !b->matrix_palette.empty();
const bool two_sided_a = (a->material) ? a->material->is_two_sided() : false;
const bool two_sided_b = (b->material) ? b->material->is_two_sided() : false;
if (skinned_a)
{
if (skinned_b)
{
// A and B are both skinned, 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);
}
}
}
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