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feat: 解析式 PBR（Cook-Torrance GGX，metallic-roughness 工作流）

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- 修 void* 指针算术警告（Texture::InitFromDds）
- Material：slot2 语义切为 metallicRoughness（glTF 约定 G=粗糙度
  B=金属度）+ 新增材质因子参数 UBO（binding 4，per-slot ring，
  创建时写死，metallic/roughness 因子乘 MR 贴图）
- simple_shader.frag：Blinn-Phong → Cook-Torrance（GGX 分布 +
  Smith 几何 + Schlick Fresnel，k=(r+1)²/8 解析光源版）；金属不参与
  漫反射；环境光暂为常数（IBL 后续）
- Model：读 aiTextureType_UNKNOWN（glTF MR 落点）+ AI_MATKEY_
  METALLIC/ROUGHNESS_FACTOR（旧资产缺键退化为电介质 0/0.5）；
  材质缓存键含因子
- main.cpp：演示场景换回 backpack（旧资产走因子路径验证 PBR 全链路）
- 旧 specular 贴图不再使用（语义被 MR 取代）
This commit is contained in:
atdunbg
2026-09-23 18:01:14 +08:00
parent 2c4efc5165
commit 89bf4256e8
23 changed files with 449 additions and 371 deletions
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shaders/simple_shader.frag
+56 -18
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@@ -1,6 +1,7 @@
#version 450
const int MAX_LIGHTS = 4;
const float PI = 3.14159265359;
struct Light {
vec4 color; // rgb = 颜色，a = 强度
@@ -35,18 +36,20 @@ layout(set = 0, binding = 0) uniform UniformBufferObject {
// 材质纹理槽（binding = Material::Slot）
layout(set = 1, binding = 0) uniform sampler2D albedoMap;
layout(set = 1, binding = 1) uniform sampler2D normalMap;
layout(set = 1, binding = 2) uniform sampler2D specularMap;
layout(set = 1, binding = 2) uniform sampler2D metallicRoughnessMap; // G=粗糙度 B=金属度
layout(set = 1, binding = 3) uniform sampler2D emissiveMap;
layout(set = 1, binding = 4) uniform MaterialParams {
vec4 factors; // x = metallic 因子，y = roughness 因子
} matParams;
layout(set = 2, binding = 0) uniform sampler2D shadowMap0; // CSM 级联 0（最近）
layout(set = 2, binding = 1) uniform sampler2D shadowMap1; // 级联 1
layout(set = 2, binding = 2) uniform sampler2D shadowMap2; // 级联 2（最远）
// 第 0 盏灯（KeyLight）的 CSM 阴影因子：0.3 影中 / 1.0 受光。
// 第 0 盏方向光（KeyLight）的 CSM 阴影因子：0.3 影中 / 1.0 受光。
// 级联按视图深度选择；采样器均 clamp-to-border 白色：
// 光视锥外自动 1.0（无阴影），省出界分支。
float ShadowFactor(vec3 N, float viewDepth) {
// 级联选择：第一个 viewDepth < split 的级联
int cascade = 2;
for (int i = 0; i < 3; ++i) {
if (viewDepth < ubo.cascadeSplits[i]) { cascade = i; break; }
@@ -54,7 +57,6 @@ float ShadowFactor(vec3 N, float viewDepth) {
vec4 ls = ubo.lightSpace[cascade] * vec4(fragWorldPos, 1.0);
vec3 proj = ls.xyz / ls.w;
// NDC [-1,1] → UV [0,1]（ortho 的 w=1）
vec2 uv = proj.xy * 0.5 + 0.5;
float closest;
@@ -62,7 +64,6 @@ float ShadowFactor(vec3 N, float viewDepth) {
else if (cascade == 1) closest = texture(shadowMap1, uv).r;
else closest = texture(shadowMap2, uv).r;
// 斜率缩放 bias：掠射面用更大的 bias 压 acne
vec3 L = normalize(-ubo.lights[0].direction.xyz);
float bias = max(0.004 * (1.0 - dot(N, L)), 0.0012);
@@ -83,15 +84,39 @@ vec3 MappedNormal(vec3 geomN, vec3 T, vec2 uv) {
return normalize(nT * sampled.x + B * sampled.y + N * sampled.z);
}
// ---- Cook-Torrance BRDF 各项 ----
float DistributionGGX(float NdotH, float roughness) {
float a = roughness * roughness;
float a2 = a * a;
float d = NdotH * NdotH * (a2 - 1.0) + 1.0;
return a2 / (PI * d * d);
}
float GeometrySmith(float NdotV, float NdotL, float roughness) {
float r = roughness + 1.0;
float k = (r * r) / 8.0; // 解析光源用此 k（IBL 才用 IBL 版本）
float gv = NdotV / (NdotV * (1.0 - k) + k);
float gl = NdotL / (NdotL * (1.0 - k) + k);
return gv * gl;
}
vec3 FresnelSchlick(float cosTheta, vec3 F0) {
return F0 + (1.0 - F0) * pow(clamp(1.0 - cosTheta, 0.0, 1.0), 5.0);
}
void main() {
vec3 albedo = texture(albedoMap, fragUV).rgb;
float specIntensity = texture(specularMap, fragUV).r;
vec4 mr = texture(metallicRoughnessMap, fragUV);
float roughness = clamp(mr.g * matParams.factors.y, 0.045, 1.0);
float metallic = clamp(mr.b * matParams.factors.x, 0.0, 1.0);
vec3 emissive = texture(emissiveMap, fragUV).rgb;
vec3 N = MappedNormal(normalize(fragNormal), fragTangent, fragUV);
vec3 V = normalize(ubo.cameraPos.xyz - fragWorldPos);
float NdotV = max(dot(N, V), 1e-4);
vec3 F0 = mix(vec3(0.04), albedo, metallic); // 电介质基准反射率 4%
vec3 result = ubo.ambientColor.rgb * albedo;
vec3 Lo = vec3(0.0);
for (int i = 0; i < MAX_LIGHTS; ++i) {
// 按类型分支：方向光无衰减；点光方向指向光源 + 平方距离衰减
@@ -100,32 +125,45 @@ void main() {
if (ubo.lights[i].params.x > 0.5) {
vec3 toLight = ubo.lights[i].position.xyz - fragWorldPos;
float d = length(toLight);
if (d >= ubo.lights[i].params.y) continue; // 衰减半径外，跳过
if (d >= ubo.lights[i].params.y) continue;
L = toLight / d;
float a = clamp(1.0 - (d * d) /
(ubo.lights[i].params.y * ubo.lights[i].params.y),
0.0, 1.0);
atten = a * a; // 平方衰减，边缘更柔和
atten = a * a;
} else {
L = normalize(-ubo.lights[i].direction.xyz);
}
float diff = max(dot(N, L), 0.0);
// Blinn-Phong 高光（半程向量；specular 图做强度系数）
vec3 H = normalize(L + V);
float spec = pow(max(dot(N, H), 0.0), 32.0) * specIntensity;
vec3 radiance = ubo.lights[i].color.rgb * ubo.lights[i].color.a * atten;
float NdotL = max(dot(N, L), 0.0);
if (NdotL <= 0.0) continue;
// Cook-Torrance 镜面项
vec3 H = normalize(V + L);
float NdotH = max(dot(N, H), 0.0);
float NdotH2 = max(dot(H, V), 0.0);
float D = DistributionGGX(NdotH, roughness);
float G = GeometrySmith(NdotV, NdotL, roughness);
vec3 F = FresnelSchlick(NdotH2, F0);
vec3 kS = F;
vec3 kD = (1.0 - kS) * (1.0 - metallic); // 金属不参与漫反射
vec3 specular = (D * G * F) /
max(4.0 * NdotV * NdotL, 1e-4);
// 阴影只来自第 0 盏方向光（CSM）
float shade = (i == 0 && ubo.lights[0].params.x < 0.5)
? ShadowFactor(N, fragViewDepth) : 1.0;
result += ubo.lights[i].color.rgb * ubo.lights[i].color.a *
(albedo * diff + vec3(spec)) * atten * shade;
Lo += (kD * albedo / PI + specular) * radiance * NdotL * shade;
}
// 自发光不经光照/阴影直接叠加
result += emissive;
// 环境光：无 IBL 的简化版（半球常数）；后续 IBL 替换
vec3 ambient = ubo.ambientColor.rgb * albedo;
outColor = vec4(result, 1.0);
vec3 color = ambient + Lo + emissive;
outColor = vec4(color, 1.0);
outVelocity = fragVelocity;
}