trianglemesh.java

Sunflow是一个照片级的渲染系统

        float va = nx * edge2x + ny * edge2y + nz * edge2z;
        float t = iv * va;
        if (!r.isInside(t))
            return;
        float ix = edge2y * r.dz - edge2z * r.dy;
        float iy = edge2z * r.dx - edge2x * r.dz;
        float iz = edge2x * r.dy - edge2y * r.dx;
        float v1 = ix * edge1x + iy * edge1y + iz * edge1z;
        float beta = iv * v1;
        if (beta < 0)
            return;
        float v2 = ix * edge0x + iy * edge0y + iz * edge0z;
        if ((v1 + v2) * v > v * v)
            return;
        float gamma = iv * v2;
        if (gamma < 0)
            return;
        r.setMax(t);
        state.setIntersection(primID, beta, gamma);
    }

    public void intersectPrimitive(Ray r, int primID, IntersectionState state) {
        // alternative test -- disabled for now
        // intersectPrimitiveRobust(r, primID, state);

        if (triaccel != null) {
            // optional fast intersection method
            triaccel[primID].intersect(r, primID, state);
            return;
        }
        intersectTriangleKensler(r, primID, state);
    }

    public int getNumPrimitives() {
        return triangles.length / 3;
    }

    public void prepareShadingState(ShadingState state) {
        state.init();
        Instance parent = state.getInstance();
        int primID = state.getPrimitiveID();
        float u = state.getU();
        float v = state.getV();
        float w = 1 - u - v;
        state.getRay().getPoint(state.getPoint());
        int tri = 3 * primID;
        int index0 = triangles[tri + 0];
        int index1 = triangles[tri + 1];
        int index2 = triangles[tri + 2];
        Point3 v0p = getPoint(index0);
        Point3 v1p = getPoint(index1);
        Point3 v2p = getPoint(index2);
        Vector3 ng = Point3.normal(v0p, v1p, v2p);
        ng = parent.transformNormalObjectToWorld(ng);
        ng.normalize();
        state.getGeoNormal().set(ng);
        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;
                float[] normals = this.normals.data;
                state.getNormal().x = w * normals[i30 + 0] + u * normals[i31 + 0] + v * normals[i32 + 0];
                state.getNormal().y = w * normals[i30 + 1] + u * normals[i31 + 1] + v * normals[i32 + 1];
                state.getNormal().z = w * normals[i30 + 2] + u * normals[i31 + 2] + v * normals[i32 + 2];
                state.getNormal().set(parent.transformNormalObjectToWorld(state.getNormal()));
                state.getNormal().normalize();
                break;
            }
            case FACEVARYING: {
                int idx = 3 * tri;
                float[] normals = this.normals.data;
                state.getNormal().x = w * normals[idx + 0] + u * normals[idx + 3] + v * normals[idx + 6];
                state.getNormal().y = w * normals[idx + 1] + u * normals[idx + 4] + v * normals[idx + 7];
                state.getNormal().z = w * normals[idx + 2] + u * normals[idx + 5] + v * normals[idx + 8];
                state.getNormal().set(parent.transformNormalObjectToWorld(state.getNormal()));
                state.getNormal().normalize();
                break;
            }
        }
        float uv00 = 0, uv01 = 0, uv10 = 0, uv11 = 0, uv20 = 0, uv21 = 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;
                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];
                break;
            }
            case FACEVARYING: {
                int idx = tri << 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];
                break;
            }
        }
        if (uvs.interp != InterpolationType.NONE) {
            // get exact uv coords and compute tangent vectors
            state.getUV().x = w * uv00 + u * uv10 + v * uv20;
            state.getUV().y = w * uv01 + u * uv11 + v * uv21;
            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 = parent.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));
    }

    public void init() {
        triaccel = null;
        int nt = getNumPrimitives();
        if (!smallTriangles) {
            // too many triangles? -- don't generate triaccel to save memory
            if (nt > 2000000) {
                UI.printWarning(Module.GEOM, "TRI - Too many triangles -- triaccel generation skipped");
                return;
            }
            triaccel = new WaldTriangle[nt];
            for (int i = 0; i < nt; i++)
                triaccel[i] = new WaldTriangle(this, i);
        }
    }

    protected Point3 getPoint(int i) {
        i *= 3;
        return new Point3(points[i], points[i + 1], points[i + 2]);
    }

    public void getPoint(int tri, int i, Point3 p) {
        int index = 3 * triangles[3 * tri + i];
        p.set(points[index], points[index + 1], points[index + 2]);
    }

    private static final class WaldTriangle {
        // private data for fast triangle intersection testing
        private int k;
        private float nu, nv, nd;
        private float bnu, bnv, bnd;
        private float cnu, cnv, cnd;

        private WaldTriangle(TriangleMesh mesh, int tri) {
            k = 0;
            tri *= 3;
            int index0 = mesh.triangles[tri + 0];
            int index1 = mesh.triangles[tri + 1];
            int index2 = mesh.triangles[tri + 2];
            Point3 v0p = mesh.getPoint(index0);
            Point3 v1p = mesh.getPoint(index1);
            Point3 v2p = mesh.getPoint(index2);
            Vector3 ng = Point3.normal(v0p, v1p, v2p);
            if (Math.abs(ng.x) > Math.abs(ng.y) && Math.abs(ng.x) > Math.abs(ng.z))
                k = 0;
            else if (Math.abs(ng.y) > Math.abs(ng.z))
                k = 1;
            else
                k = 2;
            float ax, ay, bx, by, cx, cy;
            switch (k) {
                case 0: {
                    nu = ng.y / ng.x;
                    nv = ng.z / ng.x;
                    nd = v0p.x + (nu * v0p.y) + (nv * v0p.z);
                    ax = v0p.y;
                    ay = v0p.z;
                    bx = v2p.y - ax;
                    by = v2p.z - ay;
                    cx = v1p.y - ax;
                    cy = v1p.z - ay;
                    break;
                }
                case 1: {
                    nu = ng.z / ng.y;
                    nv = ng.x / ng.y;
                    nd = (nv * v0p.x) + v0p.y + (nu * v0p.z);
                    ax = v0p.z;
                    ay = v0p.x;
                    bx = v2p.z - ax;
                    by = v2p.x - ay;
                    cx = v1p.z - ax;
                    cy = v1p.x - ay;
                    break;
                }
                case 2:
                default: {
                    nu = ng.x / ng.z;
                    nv = ng.y / ng.z;
                    nd = (nu * v0p.x) + (nv * v0p.y) + v0p.z;
                    ax = v0p.x;
                    ay = v0p.y;
                    bx = v2p.x - ax;
                    by = v2p.y - ay;
                    cx = v1p.x - ax;
                    cy = v1p.y - ay;
                }
            }
            float det = bx * cy - by * cx;
            bnu = -by / det;
            bnv = bx / det;
            bnd = (by * ax - bx * ay) / det;
            cnu = cy / det;
            cnv = -cx / det;
            cnd = (cx * ay - cy * ax) / det;
        }

        void intersectBox(Ray r, float hx, float hy, float hz, int primID, IntersectionState state) {
            switch (k) {
                case 0: {
                    float hu = hy;
                    float hv = hz;
                    float u = hu * bnu + hv * bnv + bnd;
                    if (u < 0.0f)
                        u = 0;
                    float v = hu * cnu + hv * cnv + cnd;
                    if (v < 0.0f)
                        v = 0;
                    state.setIntersection(primID, u, v);
                    return;
                }
                case 1: {
                    float hu = hz;
                    float hv = hx;
                    float u = hu * bnu + hv * bnv + bnd;
                    if (u < 0.0f)
                        u = 0;
                    float v = hu * cnu + hv * cnv + cnd;
                    if (v < 0.0f)
                        v = 0;
                    state.setIntersection(primID, u, v);
                    return;
                }
                case 2: {
                    float hu = hx;
                    float hv = hy;
                    float u = hu * bnu + hv * bnv + bnd;
                    if (u < 0.0f)
                        u = 0;
                    float v = hu * cnu + hv * cnv + cnd;
                    if (v < 0.0f)
                        v = 0;
                    state.setIntersection(primID, u, v);
                    return;
                }
            }
        }

        void intersect(Ray r, int primID, IntersectionState state) {
            switch (k) {
                case 0: {
                    float det = 1.0f / (r.dx + nu * r.dy + nv * r.dz);
                    float t = (nd - r.ox - nu * r.oy - nv * r.oz) * det;
                    if (!r.isInside(t))
                        return;
                    float hu = r.oy + t * r.dy;
                    float hv = r.oz + t * r.dz;
                    float u = hu * bnu + hv * bnv + bnd;
                    if (u < 0.0f)
                        return;
                    float v = hu * cnu + hv * cnv + cnd;
                    if (v < 0.0f)
                        return;
                    if (u + v > 1.0f)
                        return;
                    r.setMax(t);
                    state.setIntersection(primID, u, v);
                    return;
                }
                case 1: {
                    float det = 1.0f / (r.dy + nu * r.dz + nv * r.dx);
                    float t = (nd - r.oy - nu * r.oz - nv * r.ox) * det;
                    if (!r.isInside(t))
                        return;
                    float hu = r.oz + t * r.dz;
                    float hv = r.ox + t * r.dx;
                    float u = hu * bnu + hv * bnv + bnd;
                    if (u < 0.0f)
                        return;
                    float v = hu * cnu + hv * cnv + cnd;
                    if (v < 0.0f)
                        return;
                    if (u + v > 1.0f)
                        return;
                    r.setMax(t);
                    state.setIntersection(primID, u, v);
                    return;