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Merged
MichaelFisher1997 merged 3 commits into from
Dec 24, 2025
Merged

Refactor: Decompose App and Fix Vulkan Parity/SOLID issues #18

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83210f2
Refactor: Decompose App and Fix Vulkan Parity/SOLID issues
MichaelFisher1997 Dec 23, 2025
2d90eef
Fix critical review issues: CSM Z-range, ShadowMap init logging, and …
MichaelFisher1997 Dec 24, 2025
978d681
Fix final code review issues: Redundant cascade computation and debug…
MichaelFisher1997 Dec 24, 2025
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65 changes: 65 additions & 0 deletions src/engine/core/window.zig
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Original file line number Diff line number Diff line change
@@ -0,0 +1,65 @@
const std = @import("std");
const c = @import("../../c.zig").c;
const log = @import("log.zig");

pub const WindowManager = struct {
window: *c.SDL_Window,
gl_context: ?c.SDL_GLContext,
is_vulkan: bool,

pub fn init(allocator: std.mem.Allocator, use_vulkan: bool) !WindowManager {
_ = allocator;
if (c.SDL_Init(c.SDL_INIT_VIDEO) == false) {
std.debug.print("SDL Init Failed: {s}\n", .{c.SDL_GetError()});
return error.SDLInitializationFailed;
}

if (!use_vulkan) {
_ = c.SDL_GL_SetAttribute(c.SDL_GL_CONTEXT_MAJOR_VERSION, 3);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_CONTEXT_MINOR_VERSION, 3);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_CONTEXT_PROFILE_MASK, c.SDL_GL_CONTEXT_PROFILE_CORE);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_DEPTH_SIZE, 24);
}

var window_flags: u32 = c.SDL_WINDOW_RESIZABLE;
if (use_vulkan) {
window_flags |= c.SDL_WINDOW_VULKAN;
} else {
window_flags |= c.SDL_WINDOW_OPENGL;
}

const window = c.SDL_CreateWindow(
"Zig Voxel Engine",
1280,
720,
@intCast(window_flags),
);
if (window == null) {
log.log.err("Window Creation Failed: {s}", .{c.SDL_GetError()});
return error.WindowCreationFailed;
}
log.log.info("Window created successfully", .{});

var gl_context: ?c.SDL_GLContext = null;
if (!use_vulkan) {
gl_context = c.SDL_GL_CreateContext(window);
if (gl_context == null) return error.GLContextCreationFailed;
_ = c.SDL_GL_MakeCurrent(window, gl_context.?);
c.glewExperimental = c.GL_TRUE;
}

return WindowManager{
.window = window.?,
.gl_context = gl_context,
.is_vulkan = use_vulkan,
};
}

pub fn deinit(self: *WindowManager) void {
if (self.gl_context) |ctx| {
_ = c.SDL_GL_DestroyContext(ctx);
}
c.SDL_DestroyWindow(self.window);
c.SDL_Quit();
}
};
110 changes: 110 additions & 0 deletions src/engine/graphics/csm.zig
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const std = @import("std");
const Mat4 = @import("../math/mat4.zig").Mat4;
const Vec3 = @import("../math/vec3.zig").Vec3;
const rhi = @import("rhi.zig");

pub const CASCADE_COUNT = rhi.SHADOW_CASCADE_COUNT;

pub const ShadowCascades = struct {
light_space_matrices: [CASCADE_COUNT]Mat4,
cascade_splits: [CASCADE_COUNT]f32,
texel_sizes: [CASCADE_COUNT]f32,
};

pub fn computeCascades(resolution: u32, camera_fov: f32, aspect: f32, near: f32, far: f32, sun_dir: Vec3, cam_view: Mat4, z_range_01: bool) ShadowCascades {
const lambda = 0.8;
const shadow_dist = far;

var cascades: ShadowCascades = .{
.light_space_matrices = undefined,
.cascade_splits = undefined,
.texel_sizes = undefined,
};

// Calculate split distances (linear/log blend)
for (0..CASCADE_COUNT) |i| {
const p = @as(f32, @floatFromInt(i + 1)) / @as(f32, @floatFromInt(CASCADE_COUNT));
const log_split = near * std.math.pow(f32, shadow_dist / near, p);
const lin_split = near + (shadow_dist - near) * p;
cascades.cascade_splits[i] = std.math.lerp(lin_split, log_split, lambda);
}

// Calculate matrices for each cascade
var last_split = near;
for (0..CASCADE_COUNT) |i| {
const split = cascades.cascade_splits[i];

// 1. Compute bounding sphere of frustum slice (STABLE CSM approach)
const tan_fov_half = std.math.tan(camera_fov / 2.0);
const tan_fov_h_half = tan_fov_half * aspect;

const near_v = last_split;
const far_v = split;
const center_z = (near_v + far_v) / 2.0;
const center_view = Vec3.init(0, 0, -center_z);

const xf = far_v * tan_fov_h_half;
const yf = far_v * tan_fov_half;
const zf = -far_v;
const far_corner = Vec3.init(xf, yf, zf);
var radius = far_corner.sub(center_view).length();
radius = @ceil(radius * 16.0) / 16.0;

// 2. Transform center to World Space
const inv_cam_view = cam_view.inverse();
const center_world = inv_cam_view.transformPoint(center_view);

// 3. Build Light Rotation Matrix (Looking in -sun direction)
var up = Vec3.init(0, 1, 0);
if (@abs(sun_dir.y) > 0.99) up = Vec3.init(0, 0, 1);
const light_rot = Mat4.lookAt(Vec3.zero, sun_dir.scale(-1.0), up);

// 4. Transform center to Light Space
const center_ls = light_rot.transformPoint(center_world);

// 5. Snap center to texel grid in LIGHT SPACE
const texel_size = (2.0 * radius) / @as(f32, @floatFromInt(resolution));
cascades.texel_sizes[i] = texel_size;

const center_snapped = Vec3.init(
@floor(center_ls.x / texel_size) * texel_size,
@floor(center_ls.y / texel_size) * texel_size,
center_ls.z,
);

// 6. Build Ortho Projection (Centered around snapped center)
const minX = center_snapped.x - radius;
const maxX = center_snapped.x + radius;
const minY = center_snapped.y - radius;
const maxY = center_snapped.y + radius;

const maxZ = center_snapped.z + radius + 300.0;
const minZ = center_snapped.z - radius - 100.0;

var light_ortho = Mat4.identity;
light_ortho.data[0][0] = 2.0 / (maxX - minX);
light_ortho.data[3][0] = -(maxX + minX) / (maxX - minX);

light_ortho.data[1][1] = 2.0 / (maxY - minY);
light_ortho.data[3][1] = -(maxY + minY) / (maxY - minY);

if (z_range_01) {
const A = 1.0 / (maxZ - minZ);
const B = -A * minZ;
light_ortho.data[2][2] = A;
light_ortho.data[3][2] = B;
} else {
// Standard OpenGL: map closer to -1, further to 1
// maxZ is closer (less negative), minZ is further (more negative)
const A = -2.0 / (maxZ - minZ);
const B = (maxZ + minZ) / (maxZ - minZ);
light_ortho.data[2][2] = A;
light_ortho.data[3][2] = B;
}

cascades.light_space_matrices[i] = light_ortho.multiply(light_rot);
last_split = split;
}

return cascades;
}
109 changes: 5 additions & 104 deletions src/engine/graphics/shadows.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -10,8 +10,10 @@ const Shader = @import("shader.zig").Shader;

const rhi = @import("rhi.zig");

const CSM = @import("csm.zig");

pub const ShadowMap = struct {
pub const CASCADE_COUNT = rhi.SHADOW_CASCADE_COUNT;
pub const CASCADE_COUNT = CSM.CASCADE_COUNT;
depth_maps: [CASCADE_COUNT]Texture,
fbos: [CASCADE_COUNT]c.GLuint,
resolution: u32,
Expand Down Expand Up @@ -74,109 +76,8 @@ pub const ShadowMap = struct {
sh.deinit();
}

pub const ShadowCascades = struct {
light_space_matrices: [CASCADE_COUNT]Mat4,
cascade_splits: [CASCADE_COUNT]f32,
texel_sizes: [CASCADE_COUNT]f32,
};

pub fn computeCascades(resolution: u32, camera_fov: f32, aspect: f32, near: f32, far: f32, sun_dir: Vec3, cam_view: Mat4, z_range_01: bool) ShadowCascades {
const lambda = 0.8;
const shadow_dist = far;

var cascades: ShadowCascades = .{
.light_space_matrices = undefined,
.cascade_splits = undefined,
.texel_sizes = undefined,
};

// Calculate split distances (linear/log blend)
for (0..CASCADE_COUNT) |i| {
const p = @as(f32, @floatFromInt(i + 1)) / @as(f32, @floatFromInt(CASCADE_COUNT));
const log_split = near * std.math.pow(f32, shadow_dist / near, p);
const lin_split = near + (shadow_dist - near) * p;
cascades.cascade_splits[i] = std.math.lerp(lin_split, log_split, lambda);
}

// Calculate matrices for each cascade
var last_split = near;
for (0..CASCADE_COUNT) |i| {
const split = cascades.cascade_splits[i];

// 1. Compute bounding sphere of frustum slice (STABLE CSM approach)
const tan_fov_half = std.math.tan(camera_fov / 2.0);
const tan_fov_h_half = tan_fov_half * aspect;

const near_v = last_split;
const far_v = split;
const center_z = (near_v + far_v) / 2.0;
const center_view = Vec3.init(0, 0, -center_z);

const xf = far_v * tan_fov_h_half;
const yf = far_v * tan_fov_half;
const zf = -far_v;
const far_corner = Vec3.init(xf, yf, zf);
var radius = far_corner.sub(center_view).length();
radius = @ceil(radius * 16.0) / 16.0;

// 2. Transform center to World Space
const inv_cam_view = cam_view.inverse();
const center_world = inv_cam_view.transformPoint(center_view);

// 3. Build Light Rotation Matrix (Looking in -sun direction)
var up = Vec3.init(0, 1, 0);
if (@abs(sun_dir.y) > 0.99) up = Vec3.init(0, 0, 1);
const light_rot = Mat4.lookAt(Vec3.zero, sun_dir.scale(-1.0), up);

// 4. Transform center to Light Space
const center_ls = light_rot.transformPoint(center_world);

// 5. Snap center to texel grid in LIGHT SPACE
const texel_size = (2.0 * radius) / @as(f32, @floatFromInt(resolution));
cascades.texel_sizes[i] = texel_size;

const center_snapped = Vec3.init(
@floor(center_ls.x / texel_size) * texel_size,
@floor(center_ls.y / texel_size) * texel_size,
center_ls.z,
);

// 6. Build Ortho Projection (Centered around snapped center)
const minX = center_snapped.x - radius;
const maxX = center_snapped.x + radius;
const minY = center_snapped.y - radius;
const maxY = center_snapped.y + radius;

const maxZ = center_snapped.z + radius + 300.0;
const minZ = center_snapped.z - radius - 100.0;

var light_ortho = Mat4.identity;
light_ortho.data[0][0] = 2.0 / (maxX - minX);
light_ortho.data[3][0] = -(maxX + minX) / (maxX - minX);

light_ortho.data[1][1] = 2.0 / (maxY - minY);
light_ortho.data[3][1] = -(maxY + minY) / (maxY - minY);

if (z_range_01) {
const A = 1.0 / (maxZ - minZ);
const B = -A * minZ;
light_ortho.data[2][2] = A;
light_ortho.data[3][2] = B;
} else {
// Standard OpenGL: map closer to -1, further to 1
// maxZ is closer (less negative), minZ is further (more negative)
const A = -2.0 / (maxZ - minZ);
const B = (maxZ + minZ) / (maxZ - minZ);
light_ortho.data[2][2] = A;
light_ortho.data[3][2] = B;
}

cascades.light_space_matrices[i] = light_ortho.multiply(light_rot);
last_split = split;
}

return cascades;
}
pub const ShadowCascades = CSM.ShadowCascades;
pub const computeCascades = CSM.computeCascades;

/// Calculate cascade splits and matrices
pub fn update(self: *ShadowMap, camera_fov: f32, aspect: f32, near: f32, far: f32, sun_dir: Vec3, cam_pos: Vec3, cam_view: Mat4) void {
Expand Down
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