Fix direct shadow shimmering when view is changed
- Use bounding sphere of frustum instead of bbox - Snap directional light projection offset to texels
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@ -193,7 +193,8 @@ float map(float value, float min1, float max1, float min2, float max2) {
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vec3 microfacetModel(Material mat, int light_idx, Light light, vec3 P, vec3 N) {
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int csm_split_idx = getCSMSplit(light_idx, P.z);
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mat.albedo = vec4(mix(mat.albedo.rgb, csm_split_colors[csm_split_idx], 0.8), mat.albedo.a);
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// Visualize CSM splits
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//mat.albedo = vec4(mix(mat.albedo.rgb, csm_split_colors[csm_split_idx], 0.8), mat.albedo.a);
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vec3 diffuseBrdf = vec3(0); // metallic
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if (!mat.metallic) {
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@ -20,6 +20,7 @@ pub const MAX_LIGHTS = 8;
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pub const MAX_DRAW_COMMANDS = 4096;
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pub const MAX_LIGHT_COMMANDS = 2048;
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pub const CSM_SPLITS = 4;
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pub const DIRECTIONAL_SHADOW_MAP_SIZE = 2048;
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// affects how cascades are split
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// 0 - uniform
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// 1 - exponential
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@ -176,7 +177,7 @@ pub fn init(allocator: std.mem.Allocator, frame_arena: std.mem.Allocator, assetm
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checkGLError();
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std.debug.assert(render.shadow_texture_array != 0);
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gl.textureStorage3D(render.shadow_texture_array, 1, gl.DEPTH_COMPONENT16, 2048, 2048, CSM_SPLITS);
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gl.textureStorage3D(render.shadow_texture_array, 1, gl.DEPTH_COMPONENT16, DIRECTIONAL_SHADOW_MAP_SIZE, DIRECTIONAL_SHADOW_MAP_SIZE, CSM_SPLITS);
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checkGLError();
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gl.textureParameteri(render.shadow_texture_array, gl.TEXTURE_COMPARE_MODE, gl.COMPARE_REF_TO_TEXTURE);
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@ -521,7 +522,7 @@ pub fn finish(self: *Render) void {
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.directional => |dir_light| {
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light.pos = dir_light.dir.toVec4(0);
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light.color_radius = dir_light.color.toVec4(0);
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gl.viewport(0, 0, 2048, 2048);
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gl.viewport(0, 0, DIRECTIONAL_SHADOW_MAP_SIZE, DIRECTIONAL_SHADOW_MAP_SIZE);
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const camera_matrix = &self.shadow_matrices;
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@ -562,8 +563,8 @@ pub fn finish(self: *Render) void {
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var projection: Mat4 = undefined;
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{
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if (self.update_view_frustum) {
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var camera = self.camera.*;
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if (self.update_view_frustum) {
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camera.near = split_near;
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camera.far = split_far;
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const inv_csm_proj = camera.projection().mul(camera.view_mat).inv();
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@ -574,39 +575,55 @@ pub fn finish(self: *Render) void {
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}
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}
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var dir_aabb_min = Vec3.zero();
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var dir_aabb_max = Vec3.zero();
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for (self.world_view_frustum_corners[split_idx]) |corner| {
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const pos4 = view.mulByVec4(corner.toVec4(1));
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const pos = pos4.toVec3();
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dir_aabb_min = pos.min(dir_aabb_min);
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dir_aabb_max = pos.max(dir_aabb_max);
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// Find minimal bounding sphere for a frustum
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// Taken from:
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// https://lxjk.github.io/2017/04/15/Calculate-Minimal-Bounding-Sphere-of-Frustum.html
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const inv_aspect_sqr = (camera.aspect) * (camera.aspect);
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const k = @sqrt(1 + inv_aspect_sqr) * @tan(za.toRadians(camera.fovy) / 2);
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var center = Vec3.zero();
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var radius: f32 = 0;
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if (k * k >= (camera.far - camera.near) / (camera.far + camera.near)) {
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center = Vec3.new(0, 0, -camera.far);
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radius = camera.far * k;
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} else {
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center = Vec3.new(0, 0, -0.5 * (camera.far + camera.near) * (1 + k * k));
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radius = 0.5 * @sqrt((camera.far - camera.near) * (camera.far - camera.near) + 2 * (camera.far * camera.far + camera.near * camera.near) * k * k + (camera.far + camera.near) * (camera.far + camera.near) * k * k * k * k);
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}
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// Flip z because it's negative in view space, but near, far is positive
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{
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const min_z = dir_aabb_min.z();
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dir_aabb_min.zMut().* = -dir_aabb_max.z();
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dir_aabb_max.zMut().* = -min_z;
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}
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const b_sphere = math.AABB.fromMinMax(dir_aabb_min, dir_aabb_max).toSphere();
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center = camera.view_mat.inv().mulByVec4(center.toVec4(1)).toVec3();
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center = view.mulByVec4(center.toVec4(1)).toVec3();
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// NOTE: Use bounding sphere instead of AABB to prevent split size changing with rotation
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projection = math.orthographic(
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b_sphere.origin.x() - b_sphere.radius,
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b_sphere.origin.x() + b_sphere.radius,
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b_sphere.origin.y() - b_sphere.radius,
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b_sphere.origin.y() + b_sphere.radius,
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b_sphere.origin.z() - b_sphere.radius,
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b_sphere.origin.z() + b_sphere.radius,
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center.x() - radius - 0.0001,
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center.x() + radius,
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center.y() - radius,
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center.y() + radius,
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-center.z() - radius,
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-center.z() + radius,
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);
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}
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var shadow_view_proj = projection.mul(view);
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// Snap to texels
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{
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var shadow_origin = shadow_view_proj.mulByVec4(Vec4.new(0, 0, 0, 1));
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shadow_origin = shadow_origin.scale(1.0 / shadow_origin.w());
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shadow_origin = shadow_origin.scale(DIRECTIONAL_SHADOW_MAP_SIZE / 2);
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var rounded_origin: Vec4 = undefined;
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rounded_origin.data = @round(shadow_origin.data);
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var offset = rounded_origin.sub(shadow_origin).toVec2().toVec3(0);
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offset = offset.scale(2.0 / @as(f32, DIRECTIONAL_SHADOW_MAP_SIZE));
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projection = projection.translate(offset);
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shadow_view_proj = projection.mul(view);
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}
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camera_matrix.* = .{
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.view = view,
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.projection = projection,
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};
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const shadow_view_proj = projection.mul(view);
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dir_view_proj_mat[split_idx] = shadow_view_proj;
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const light_frustum = math.Frustum.new(shadow_view_proj);
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@ -1116,6 +1133,8 @@ pub const Uniform = enum(gl.GLint) {
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// TODO: support ortho
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pub const Camera = struct {
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pos: Vec3 = Vec3.zero(),
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fovy: f32 = 60,
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aspect: f32 = 1,
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near: f32 = 0.1,
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@ -230,8 +230,7 @@ export fn game_init(global_allocator: *std.mem.Allocator) void {
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.mesh = .{
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.handle = a.Meshes.plane.Plane,
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.material = .{
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.blend_mode = .AlphaBlend,
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.albedo = Vec4.new(1, 1, 1, 0.5),
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.albedo = Vec4.one(),
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.normal_map = a.Textures.@"tile.norm",
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},
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.override_material = true,
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@ -74,7 +74,8 @@ pub const FreeLookCamera = struct {
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const movement = right.scale(move.x()).add(forward.scale(move.y())).add(up.scale(move.z()));
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self.pos = self.pos.add(movement.scale(self.move_speed * dt));
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// TODO: refactor
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self.camera.pos = self.pos;
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self.camera.view_mat = Mat4.lookAt(self.pos, self.pos.add(forward), Vec3.up());
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}
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};
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@ -100,10 +100,9 @@ pub const AABB = struct {
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}
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pub fn toSphere(self: *const AABB) BoundingSphere {
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const max_extent = @max(@max(self.extents.x(), self.extents.y()), self.extents.z());
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return BoundingSphere{
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.origin = self.origin,
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.radius = max_extent,
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.radius = self.extents.length(),
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};
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}
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};
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@ -111,6 +110,10 @@ pub const AABB = struct {
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pub const BoundingSphere = struct {
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origin: Vec3 = Vec3.zero(),
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radius: f32 = 0,
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pub fn new(origin: Vec3, radius: f32) BoundingSphere {
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return BoundingSphere{ .origin = origin, .radius = radius };
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}
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};
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pub const Frustum = struct {
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