fireball/lib/renderers/shaders/ShaderChunk/cube_uv_reflection_fragment.glsl

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2018-12-25 13:59:22 +00:00
#ifdef ENVMAP_TYPE_CUBE_UV
#define cubeUV_textureSize (1024.0)
int getFaceFromDirection(vec3 direction) {
vec3 absDirection = abs(direction);
int face = -1;
if( absDirection.x > absDirection.z ) {
if(absDirection.x > absDirection.y )
face = direction.x > 0.0 ? 0 : 3;
else
face = direction.y > 0.0 ? 1 : 4;
}
else {
if(absDirection.z > absDirection.y )
face = direction.z > 0.0 ? 2 : 5;
else
face = direction.y > 0.0 ? 1 : 4;
}
return face;
}
#define cubeUV_maxLods1 (log2(cubeUV_textureSize*0.25) - 1.0)
#define cubeUV_rangeClamp (exp2((6.0 - 1.0) * 2.0))
vec2 MipLevelInfo( vec3 vec, float roughnessLevel, float roughness ) {
float scale = exp2(cubeUV_maxLods1 - roughnessLevel);
float dxRoughness = dFdx(roughness);
float dyRoughness = dFdy(roughness);
vec3 dx = dFdx( vec * scale * dxRoughness );
vec3 dy = dFdy( vec * scale * dyRoughness );
float d = max( dot( dx, dx ), dot( dy, dy ) );
// Clamp the value to the max mip level counts. hard coded to 6 mips
d = clamp(d, 1.0, cubeUV_rangeClamp);
float mipLevel = 0.5 * log2(d);
return vec2(floor(mipLevel), fract(mipLevel));
}
#define cubeUV_maxLods2 (log2(cubeUV_textureSize*0.25) - 2.0)
#define cubeUV_rcpTextureSize (1.0 / cubeUV_textureSize)
vec2 getCubeUV(vec3 direction, float roughnessLevel, float mipLevel) {
mipLevel = roughnessLevel > cubeUV_maxLods2 - 3.0 ? 0.0 : mipLevel;
float a = 16.0 * cubeUV_rcpTextureSize;
vec2 exp2_packed = exp2( vec2( roughnessLevel, mipLevel ) );
vec2 rcp_exp2_packed = vec2( 1.0 ) / exp2_packed;
// float powScale = exp2(roughnessLevel + mipLevel);
float powScale = exp2_packed.x * exp2_packed.y;
// float scale = 1.0 / exp2(roughnessLevel + 2.0 + mipLevel);
float scale = rcp_exp2_packed.x * rcp_exp2_packed.y * 0.25;
// float mipOffset = 0.75*(1.0 - 1.0/exp2(mipLevel))/exp2(roughnessLevel);
float mipOffset = 0.75*(1.0 - rcp_exp2_packed.y) * rcp_exp2_packed.x;
bool bRes = mipLevel == 0.0;
scale = bRes && (scale < a) ? a : scale;
vec3 r;
vec2 offset;
int face = getFaceFromDirection(direction);
float rcpPowScale = 1.0 / powScale;
if( face == 0) {
r = vec3(direction.x, -direction.z, direction.y);
offset = vec2(0.0+mipOffset,0.75 * rcpPowScale);
offset.y = bRes && (offset.y < 2.0*a) ? a : offset.y;
}
else if( face == 1) {
r = vec3(direction.y, direction.x, direction.z);
offset = vec2(scale+mipOffset, 0.75 * rcpPowScale);
offset.y = bRes && (offset.y < 2.0*a) ? a : offset.y;
}
else if( face == 2) {
r = vec3(direction.z, direction.x, direction.y);
offset = vec2(2.0*scale+mipOffset, 0.75 * rcpPowScale);
offset.y = bRes && (offset.y < 2.0*a) ? a : offset.y;
}
else if( face == 3) {
r = vec3(direction.x, direction.z, direction.y);
offset = vec2(0.0+mipOffset,0.5 * rcpPowScale);
offset.y = bRes && (offset.y < 2.0*a) ? 0.0 : offset.y;
}
else if( face == 4) {
r = vec3(direction.y, direction.x, -direction.z);
offset = vec2(scale+mipOffset, 0.5 * rcpPowScale);
offset.y = bRes && (offset.y < 2.0*a) ? 0.0 : offset.y;
}
else {
r = vec3(direction.z, -direction.x, direction.y);
offset = vec2(2.0*scale+mipOffset, 0.5 * rcpPowScale);
offset.y = bRes && (offset.y < 2.0*a) ? 0.0 : offset.y;
}
r = normalize(r);
float texelOffset = 0.5 * cubeUV_rcpTextureSize;
vec2 s = ( r.yz / abs( r.x ) + vec2( 1.0 ) ) * 0.5;
vec2 base = offset + vec2( texelOffset );
return base + s * ( scale - 2.0 * texelOffset );
}
#define cubeUV_maxLods3 (log2(cubeUV_textureSize*0.25) - 3.0)
vec4 textureCubeUV( sampler2D envMap, vec3 reflectedDirection, float roughness ) {
float roughnessVal = roughness* cubeUV_maxLods3;
float r1 = floor(roughnessVal);
float r2 = r1 + 1.0;
float t = fract(roughnessVal);
vec2 mipInfo = MipLevelInfo(reflectedDirection, r1, roughness);
float s = mipInfo.y;
float level0 = mipInfo.x;
float level1 = level0 + 1.0;
level1 = level1 > 5.0 ? 5.0 : level1;
// round to nearest mipmap if we are not interpolating.
level0 += min( floor( s + 0.5 ), 5.0 );
// Tri linear interpolation.
vec2 uv_10 = getCubeUV(reflectedDirection, r1, level0);
vec4 color10 = envMapTexelToLinear(texture2D(envMap, uv_10));
vec2 uv_20 = getCubeUV(reflectedDirection, r2, level0);
vec4 color20 = envMapTexelToLinear(texture2D(envMap, uv_20));
vec4 result = mix(color10, color20, t);
return vec4(result.rgb, 1.0);
}
#endif