Add 9-tap PCF soft shadows and normal-offset bias to all fragment shaders

Replaces single-tap shadow sampling with 3x3 grid PCF (36-sample equivalent
with hardware bilinear filtering) for smooth shadow edges. Adds normal-offset
bias to eliminate shadow acne on oblique surfaces without peter-panning.
This commit is contained in:
Kelsi 2026-02-23 04:14:27 -08:00
parent ae3903561c
commit 98fb6b47da
4 changed files with 65 additions and 8 deletions

View file

@ -43,6 +43,18 @@ layout(location = 4) in vec3 Bitangent;
layout(location = 0) out vec4 outColor;
const float SHADOW_TEXEL = 1.0 / 4096.0;
float sampleShadowPCF(sampler2DShadow smap, vec3 coords) {
float shadow = 0.0;
for (int x = -1; x <= 1; ++x) {
for (int y = -1; y <= 1; ++y) {
shadow += texture(smap, vec3(coords.xy + vec2(x, y) * SHADOW_TEXEL, coords.z));
}
}
return shadow / 9.0;
}
// LOD factor from screen-space UV derivatives
float computeLodFactor() {
vec2 dx = dFdx(TexCoord);
@ -149,14 +161,16 @@ void main() {
float shadow = 1.0;
if (shadowParams.x > 0.5) {
vec4 lsPos = lightSpaceMatrix * vec4(FragPos, 1.0);
float normalOffset = SHADOW_TEXEL * 2.0 * (1.0 - abs(dot(norm, ldir)));
vec3 biasedPos = FragPos + norm * normalOffset;
vec4 lsPos = lightSpaceMatrix * vec4(biasedPos, 1.0);
vec3 proj = lsPos.xyz / lsPos.w;
proj.xy = proj.xy * 0.5 + 0.5;
if (proj.x >= 0.0 && proj.x <= 1.0 &&
proj.y >= 0.0 && proj.y <= 1.0 &&
proj.z >= 0.0 && proj.z <= 1.0) {
float bias = max(0.0005 * (1.0 - dot(norm, ldir)), 0.00005);
shadow = texture(uShadowMap, vec3(proj.xy, proj.z - bias));
shadow = sampleShadowPCF(uShadowMap, vec3(proj.xy, proj.z - bias));
}
shadow = mix(1.0, shadow, shadowParams.y);
}

View file

@ -37,6 +37,18 @@ layout(location = 4) in float ModelHeight;
layout(location = 0) out vec4 outColor;
const float SHADOW_TEXEL = 1.0 / 4096.0;
float sampleShadowPCF(sampler2DShadow smap, vec3 coords) {
float shadow = 0.0;
for (int x = -1; x <= 1; ++x) {
for (int y = -1; y <= 1; ++y) {
shadow += texture(smap, vec3(coords.xy + vec2(x, y) * SHADOW_TEXEL, coords.z));
}
}
return shadow / 9.0;
}
// 4x4 Bayer dither matrix (normalized to 0..1)
float bayerDither4x4(ivec2 p) {
int idx = (p.x & 3) + (p.y & 3) * 4;
@ -126,14 +138,16 @@ void main() {
spec = pow(max(dot(norm, halfDir), 0.0), 32.0) * specularIntensity;
if (shadowParams.x > 0.5) {
vec4 lsPos = lightSpaceMatrix * vec4(FragPos, 1.0);
float normalOffset = SHADOW_TEXEL * 2.0 * (1.0 - abs(dot(norm, ldir)));
vec3 biasedPos = FragPos + norm * normalOffset;
vec4 lsPos = lightSpaceMatrix * vec4(biasedPos, 1.0);
vec3 proj = lsPos.xyz / lsPos.w;
proj.xy = proj.xy * 0.5 + 0.5;
if (proj.x >= 0.0 && proj.x <= 1.0 &&
proj.y >= 0.0 && proj.y <= 1.0 &&
proj.z >= 0.0 && proj.z <= 1.0) {
float bias = max(0.0005 * (1.0 - abs(dot(norm, ldir))), 0.00005);
shadow = texture(uShadowMap, vec3(proj.xy, proj.z - bias));
shadow = sampleShadowPCF(uShadowMap, vec3(proj.xy, proj.z - bias));
}
shadow = mix(1.0, shadow, shadowParams.y);
}

View file

@ -37,6 +37,18 @@ layout(location = 3) in vec2 LayerUV;
layout(location = 0) out vec4 outColor;
const float SHADOW_TEXEL = 1.0 / 4096.0;
float sampleShadowPCF(sampler2DShadow smap, vec3 coords) {
float shadow = 0.0;
for (int x = -1; x <= 1; ++x) {
for (int y = -1; y <= 1; ++y) {
shadow += texture(smap, vec3(coords.xy + vec2(x, y) * SHADOW_TEXEL, coords.z));
}
}
return shadow / 9.0;
}
float sampleAlpha(sampler2D tex, vec2 uv) {
vec2 edge = min(uv, 1.0 - uv);
float border = min(edge.x, edge.y);
@ -80,12 +92,15 @@ void main() {
float shadow = 1.0;
if (shadowParams.x > 0.5) {
vec4 lsPos = lightSpaceMatrix * vec4(FragPos, 1.0);
vec3 ldir = normalize(-lightDir.xyz);
float normalOffset = SHADOW_TEXEL * 2.0 * (1.0 - abs(dot(norm, ldir)));
vec3 biasedPos = FragPos + norm * normalOffset;
vec4 lsPos = lightSpaceMatrix * vec4(biasedPos, 1.0);
vec3 proj = lsPos.xyz / lsPos.w;
proj.xy = proj.xy * 0.5 + 0.5;
if (proj.x >= 0.0 && proj.x <= 1.0 && proj.y >= 0.0 && proj.y <= 1.0 && proj.z <= 1.0) {
float bias = 0.0002;
shadow = texture(uShadowMap, vec3(proj.xy, proj.z - bias));
shadow = sampleShadowPCF(uShadowMap, vec3(proj.xy, proj.z - bias));
shadow = mix(1.0, shadow, shadowParams.y);
}
}

View file

@ -43,6 +43,18 @@ layout(location = 5) in vec3 Bitangent;
layout(location = 0) out vec4 outColor;
const float SHADOW_TEXEL = 1.0 / 4096.0;
float sampleShadowPCF(sampler2DShadow smap, vec3 coords) {
float shadow = 0.0;
for (int x = -1; x <= 1; ++x) {
for (int y = -1; y <= 1; ++y) {
shadow += texture(smap, vec3(coords.xy + vec2(x, y) * SHADOW_TEXEL, coords.z));
}
}
return shadow / 9.0;
}
// LOD factor from screen-space UV derivatives
float computeLodFactor() {
vec2 dx = dFdx(TexCoord);
@ -155,14 +167,16 @@ void main() {
float shadow = 1.0;
if (shadowParams.x > 0.5) {
vec4 lsPos = lightSpaceMatrix * vec4(FragPos, 1.0);
float normalOffset = SHADOW_TEXEL * 2.0 * (1.0 - abs(dot(norm, ldir)));
vec3 biasedPos = FragPos + norm * normalOffset;
vec4 lsPos = lightSpaceMatrix * vec4(biasedPos, 1.0);
vec3 proj = lsPos.xyz / lsPos.w;
proj.xy = proj.xy * 0.5 + 0.5;
if (proj.x >= 0.0 && proj.x <= 1.0 &&
proj.y >= 0.0 && proj.y <= 1.0 &&
proj.z >= 0.0 && proj.z <= 1.0) {
float bias = max(0.0005 * (1.0 - dot(norm, ldir)), 0.00005);
shadow = texture(uShadowMap, vec3(proj.xy, proj.z - bias));
shadow = sampleShadowPCF(uShadowMap, vec3(proj.xy, proj.z - bias));
}
shadow = mix(1.0, shadow, shadowParams.y);
}