public void prepareShadingState(ShadingState state) {
state.init();
Instance parent = state.getInstance();
int primID = state.getPrimitiveID();
float u = state.getU();
float v = state.getV();
state.getRay().getPoint(state.getPoint());
int quad = 4 * primID;
int index0 = quads[quad + 0];
int index1 = quads[quad + 1];
int index2 = quads[quad + 2];
int index3 = quads[quad + 3];
Point3 v0p = getPoint(index0);
Point3 v1p = getPoint(index1);
Point3 v2p = getPoint(index2);
Point3 v3p = getPoint(index2);
float tanux = (1 - v) * (v1p.x - v0p.x) + v * (v2p.x - v3p.x);
float tanuy = (1 - v) * (v1p.y - v0p.y) + v * (v2p.y - v3p.y);
float tanuz = (1 - v) * (v1p.z - v0p.z) + v * (v2p.z - v3p.z);
float tanvx = (1 - u) * (v3p.x - v0p.x) + u * (v2p.x - v1p.x);
float tanvy = (1 - u) * (v3p.y - v0p.y) + u * (v2p.y - v1p.y);
float tanvz = (1 - u) * (v3p.z - v0p.z) + u * (v2p.z - v1p.z);
float nx = tanuy * tanvz - tanuz * tanvy;
float ny = tanuz * tanvx - tanux * tanvz;
float nz = tanux * tanvy - tanuy * tanvx;
Vector3 ng = new Vector3(nx, ny, nz);
ng = state.transformNormalObjectToWorld(ng);
ng.normalize();
state.getGeoNormal().set(ng);
float k00 = (1 - u) * (1 - v);
float k10 = u * (1 - v);
float k01 = (1 - u) * v;
float k11 = u * v;
switch (normals.interp) {
case NONE:
case FACE:
{
state.getNormal().set(ng);
break;
}
case VERTEX:
{
int i30 = 3 * index0;
int i31 = 3 * index1;
int i32 = 3 * index2;
int i33 = 3 * index3;
float[] normals = this.normals.data;
state.getNormal().x =
k00 * normals[i30 + 0]
+ k10 * normals[i31 + 0]
+ k11 * normals[i32 + 0]
+ k01 * normals[i33 + 0];
state.getNormal().y =
k00 * normals[i30 + 1]
+ k10 * normals[i31 + 1]
+ k11 * normals[i32 + 1]
+ k01 * normals[i33 + 1];
state.getNormal().z =
k00 * normals[i30 + 2]
+ k10 * normals[i31 + 2]
+ k11 * normals[i32 + 2]
+ k01 * normals[i33 + 2];
state.getNormal().set(state.transformNormalObjectToWorld(state.getNormal()));
state.getNormal().normalize();
break;
}
case FACEVARYING:
{
int idx = 3 * quad;
float[] normals = this.normals.data;
state.getNormal().x =
k00 * normals[idx + 0]
+ k10 * normals[idx + 3]
+ k11 * normals[idx + 6]
+ k01 * normals[idx + 9];
state.getNormal().y =
k00 * normals[idx + 1]
+ k10 * normals[idx + 4]
+ k11 * normals[idx + 7]
+ k01 * normals[idx + 10];
state.getNormal().z =
k00 * normals[idx + 2]
+ k10 * normals[idx + 5]
+ k11 * normals[idx + 8]
+ k01 * normals[idx + 11];
state.getNormal().set(state.transformNormalObjectToWorld(state.getNormal()));
state.getNormal().normalize();
break;
}
}
float uv00 = 0, uv01 = 0, uv10 = 0, uv11 = 0, uv20 = 0, uv21 = 0, uv30 = 0, uv31 = 0;
switch (uvs.interp) {
case NONE:
case FACE:
{
state.getUV().x = 0;
state.getUV().y = 0;
break;
}
case VERTEX:
{
int i20 = 2 * index0;
int i21 = 2 * index1;
int i22 = 2 * index2;
int i23 = 2 * index3;
float[] uvs = this.uvs.data;
uv00 = uvs[i20 + 0];
uv01 = uvs[i20 + 1];
uv10 = uvs[i21 + 0];
uv11 = uvs[i21 + 1];
uv20 = uvs[i22 + 0];
uv21 = uvs[i22 + 1];
uv20 = uvs[i23 + 0];
uv21 = uvs[i23 + 1];
break;
}
case FACEVARYING:
{
int idx = quad << 1;
float[] uvs = this.uvs.data;
uv00 = uvs[idx + 0];
uv01 = uvs[idx + 1];
uv10 = uvs[idx + 2];
uv11 = uvs[idx + 3];
uv20 = uvs[idx + 4];
uv21 = uvs[idx + 5];
uv30 = uvs[idx + 6];
uv31 = uvs[idx + 7];
break;
}
}
if (uvs.interp != InterpolationType.NONE) {
// get exact uv coords and compute tangent vectors
state.getUV().x = k00 * uv00 + k10 * uv10 + k11 * uv20 + k01 * uv30;
state.getUV().y = k00 * uv01 + k10 * uv11 + k11 * uv21 + k01 * uv31;
float du1 = uv00 - uv20;
float du2 = uv10 - uv20;
float dv1 = uv01 - uv21;
float dv2 = uv11 - uv21;
Vector3 dp1 = Point3.sub(v0p, v2p, new Vector3()), dp2 = Point3.sub(v1p, v2p, new Vector3());
float determinant = du1 * dv2 - dv1 * du2;
if (determinant == 0.0f) {
// create basis in world space
state.setBasis(OrthoNormalBasis.makeFromW(state.getNormal()));
} else {
float invdet = 1.f / determinant;
// Vector3 dpdu = new Vector3();
// dpdu.x = (dv2 * dp1.x - dv1 * dp2.x) * invdet;
// dpdu.y = (dv2 * dp1.y - dv1 * dp2.y) * invdet;
// dpdu.z = (dv2 * dp1.z - dv1 * dp2.z) * invdet;
Vector3 dpdv = new Vector3();
dpdv.x = (-du2 * dp1.x + du1 * dp2.x) * invdet;
dpdv.y = (-du2 * dp1.y + du1 * dp2.y) * invdet;
dpdv.z = (-du2 * dp1.z + du1 * dp2.z) * invdet;
dpdv = state.transformVectorObjectToWorld(dpdv);
// create basis in world space
state.setBasis(OrthoNormalBasis.makeFromWV(state.getNormal(), dpdv));
}
} else state.setBasis(OrthoNormalBasis.makeFromW(state.getNormal()));
int shaderIndex = faceShaders == null ? 0 : (faceShaders[primID] & 0xFF);
state.setShader(parent.getShader(shaderIndex));
state.setModifier(parent.getModifier(shaderIndex));
}
