Exemplo n.º 1
0
Point3 knot_fn(float s, float t)
{
    const float a = 0.5f;
    const float b = 0.3f;
    const float c = 0.5f;
    const float d = 0.1f;
    const float u = (1 - s) * 2 * PARG_TWOPI;
    const float v = t * PARG_TWOPI;
    const float r = a + b * cos(1.5f * u);
    const float x = r * cos(u);
    const float y = r * sin(u);
    const float z = c * sin(1.5f * u);

    Vector3 dv;
    dv.x =
        -1.5f * b * sin(1.5f * u) * cos(u) - (a + b * cos(1.5f * u)) * sin(u);
    dv.y =
        -1.5f * b * sin(1.5f * u) * sin(u) + (a + b * cos(1.5f * u)) * cos(u);
    dv.z = 1.5f * c * cos(1.5f * u);

    Vector3 q = V3Normalize(dv);
    Vector3 qvn = V3Normalize((Vector3){q.y, -q.x, 0});
    Vector3 ww = V3Cross(q, qvn);

    Point3 range;
    range.x = x + d * (qvn.x * cos(v) + ww.x * sin(v));
    range.y = y + d * (qvn.y * cos(v) + ww.y * sin(v));
    range.z = z + d * ww.z * sin(v);
    return range;
}
Exemplo n.º 2
0
parg_mesh* parg_mesh_knot(int slices, int stacks, float major, float minor)
{
    parg_mesh* surf = malloc(sizeof(struct parg_mesh_s));
    float ds = 1.0f / slices;
    float dt = 1.0f / stacks;
    int vertexCount = slices * stacks * 3;
    int vertexStride = sizeof(float) * 3;
    surf->coords =
        parg_buffer_alloc(vertexCount * vertexStride, PARG_GPU_ARRAY);
    surf->normals =
        parg_buffer_alloc(vertexCount * vertexStride, PARG_GPU_ARRAY);
    surf->uvs = 0;
    Point3* position = (Point3*) parg_buffer_lock(surf->coords, PARG_WRITE);
    Vector3* normal = (Vector3*) parg_buffer_lock(surf->normals, PARG_WRITE);
    for (float s = 0; s < 1 - ds / 2; s += ds) {
        for (float t = 0; t < 1 - dt / 2; t += dt) {
            const float E = 0.01f;
            Point3 p = knot_fn(s, t);
            Vector3 u = P3Sub(knot_fn(s + E, t), p);
            Vector3 v = P3Sub(knot_fn(s, t + E), p);
            Vector3 n = V3Normalize(V3Cross(u, v));
            *position++ = p;
            *normal++ = n;
        }
    }
    parg_buffer_unlock(surf->coords);
    parg_buffer_unlock(surf->normals);

    surf->ntriangles = slices * stacks * 2;
    int indexCount = surf->ntriangles * 3;
    surf->indices = parg_buffer_alloc(indexCount * 2, PARG_GPU_ELEMENTS);
    uint16_t* index = (uint16_t*) parg_buffer_lock(surf->indices, PARG_WRITE);
    int v = 0;
    for (int i = 0; i < slices - 1; i++) {
        for (int j = 0; j < stacks; j++) {
            int next = (j + 1) % stacks;
            *index++ = v + next + stacks;
            *index++ = v + next;
            *index++ = v + j;
            *index++ = v + j;
            *index++ = v + j + stacks;
            *index++ = v + next + stacks;
        }
        v += stacks;
    }
    for (int j = 0; j < stacks; j++) {
        int next = (j + 1) % stacks;
        *index++ = next;
        *index++ = v + next;
        *index++ = v + j;
        *index++ = v + j;
        *index++ = j;
        *index++ = next;
    }
    parg_buffer_unlock(surf->indices);
    return surf;
}
Exemplo n.º 3
0
Point3 *NormalToFace(Face *f, Point3 *n)
{
 Point3 t1,t2;

 V3Sub(f->v[1],f->v[0],&t1);
 V3Sub(f->v[2],f->v[0],&t2);
 V3Cross(&t1,&t2,n);

 return n;
}
Exemplo n.º 4
0
Point3 *NormalToFace(Point3 *v, Face *f, Point3 *n)
{
    Point3 t1,t2;

    V3Sub(&(v[f->v[1]]),&(v[f->v[0]]),&t1);
    V3Sub(&(v[f->v[2]]),&(v[f->v[0]]),&t2);
    V3Cross(&t1,&t2,n);

    return n;
}
void PxcLtbComputeJv(Vec3V* jv, const PxcFsData& m, const PxcSIMDSpatial* velocity)
{
	typedef PxcArticulationFnsSimd<PxcArticulationFnsSimdBase> Fns;
	const PxcLtbRow* rows = getLtbRows(m);
	const PxcFsRow* fsRows = getFsRows(m);
	const PxcFsJointVectors* jointVectors = getJointVectors(m);

	PX_UNUSED(rows);
	PX_UNUSED(fsRows);

	for(PxU32 i=1;i<m.linkCount;i++)
	{
		PxcSIMDSpatial pv = velocity[m.parent[i]], v = velocity[i];

		Vec3V parentOffset = V3Add(jointVectors[i].jointOffset, jointVectors[i].parentOffset);

		Vec3V k0v = V3Add(pv.linear, V3Cross(pv.angular, parentOffset)),
			  k1v = V3Add(v.linear,  V3Cross(v.angular,jointVectors[i].jointOffset));
		jv[i] = V3Sub(k0v, k1v);
	}
}
PX_FORCE_INLINE PxcSIMDSpatial propagateDrivenImpulse(const PxcFsRow& row, 
													  const PxcFsJointVectors& jv,
													  Vec3V& SZMinusQ, 
													  const PxcSIMDSpatial& Z,
													  const Vec3V& Q)
{
	typedef PxcArticulationFnsSimd<PxcArticulationFnsSimdBase> Fns;

	SZMinusQ = V3Sub(V3Add(Z.angular, V3Cross(Z.linear,jv.jointOffset)), Q);
	PxcSIMDSpatial result = Fns::translateForce(jv.parentOffset, Z - Fns::axisMultiply(row.DSI, SZMinusQ));

	return result;
}
Exemplo n.º 7
0
Plane *CalcPlane(Vector3 *p0, Vector3 *p1, Vector3 *p2, Plane *p )
{
 Vector3 v1,v2;
 Vector3 *N;
 N=&(p->N);


 V3Sub(p1,p0,&v1);
 V3Sub(p2,p0,&v2);
 V3Cross(&v1,&v2,N);
 if(N->x==0.0 && N->y==0.0 && N->z==0.0) return NULL;

 V3Normalize(N);

 p->off=V3Dot(N,p0);

 return p;
}
Exemplo n.º 8
0
void
Example1()
{
	Vector4	*a, *b, *c, r;
	Vector3 *a1, *b1, r1;

	a = V4New(1.0, 0.0, 0.0, 0.0);
	b = V4New(0.0, 1.0, 0.0, 0.0);
	c = V4New(0.0, 0.0, 1.0, 0.0);

	a1 = V3New(1.0, 0.0, 0.0);
	b1 = V3New(0.0, 1.0, 0.0);

	V3Cross(a1, b1, &r1);
	V4Cross(a, b, c, &r);

	printf("(%lf, %lf, %lf)\n", r1.x, r1.y, r1.z);
	printf("(%lf, %lf, %lf, %lf)\n", r.x, r.y, r.z, r.w);
}
Exemplo n.º 9
0
/*!
   \brief Define plane 

   \param p1,p2,p3 three point on plane
   \param[out] plane plane defintion

   \return 1
 */
int P3toPlane(Point3 p1, Point3 p2, Point3 p3, float *plane)
{
    Point3 v1, v2, norm;

    v1[X] = p1[X] - p3[X];
    v1[Y] = p1[Y] - p3[Y];
    v1[Z] = p1[Z] - p3[Z];

    v2[X] = p2[X] - p3[X];
    v2[Y] = p2[Y] - p3[Y];
    v2[Z] = p2[Z] - p3[Z];

    V3Cross(v1, v2, norm);

    plane[X] = norm[X];
    plane[Y] = norm[Y];
    plane[Z] = norm[Z];
    plane[W] = -p3[X] * norm[X] - p3[Y] * norm[Y] - p3[Z] * norm[Z];

    return (1);
}
Exemplo n.º 10
0
void SetupPolygon(PolygonData *ply)
{
	Vec3 V1, V2, N;
	float *pts;

	assert(ply != NULL);
	assert(ply->npts >= 3);

	pts = ply->pts;

	assert(pts != NULL);

	/* Compute plane normal. (based on first three vertices) */
	V1.x = pts[3] - pts[0];
	V2.x = pts[6] - pts[0];
	V1.y = pts[4] - pts[1];
	V2.y = pts[7] - pts[1];
	V1.z = pts[5] - pts[2];
	V2.z = pts[8] - pts[2];

	V3Cross(&N, &V1, &V2);
	V3Normalize(&N);
	ply->nx = (float)N.x;
	ply->ny = (float)N.y;
	ply->nz = (float)N.z;

	/* Determine axis of greatest projection. */
	if(fabs(N.x) > fabs(N.z))
	{
		if(fabs(N.x) > fabs(N.y))
			ply->axis = X_AXIS;
		else
			ply->axis = Y_AXIS;
	}
	else if(fabs(N.y) > fabs(N.z))
		ply->axis = Y_AXIS;
	else
		ply->axis = Z_AXIS;
}
Exemplo n.º 11
0
parg_mesh* parg_mesh_torus(int slices, int stacks, float major, float minor)
{
    parg_mesh* surf = malloc(sizeof(struct parg_mesh_s));
    float dphi = PARG_TWOPI / stacks;
    float dtheta = PARG_TWOPI / slices;
    int vertexCount = slices * stacks * 3;
    int vertexStride = sizeof(float) * 3;
    surf->coords =
        parg_buffer_alloc(vertexCount * vertexStride, PARG_GPU_ARRAY);
    surf->uvs = 0;
    Point3* position = (Point3*) parg_buffer_lock(surf->coords, PARG_WRITE);
    for (int slice = 0; slice < slices; slice++) {
        float theta = slice * dtheta;
        for (int stack = 0; stack < stacks; stack++) {
            float phi = stack * dphi;
            *position++ = torus_fn(major, minor, phi, theta);
        }
    }
    parg_buffer_unlock(surf->coords);

    surf->normals =
        parg_buffer_alloc(vertexCount * vertexStride, PARG_GPU_ARRAY);
    Vector3* normal = (Vector3*) parg_buffer_lock(surf->normals, PARG_WRITE);
    for (int slice = 0; slice < slices; slice++) {
        float theta = slice * dtheta;
        for (int stack = 0; stack < stacks; stack++) {
            float phi = stack * dphi;
            Point3 p = torus_fn(major, minor, phi, theta);
            Point3 p1 = torus_fn(major, minor, phi, theta + 0.01);
            Point3 p2 = torus_fn(major, minor, phi + 0.01, theta);
            Vector3 du = P3Sub(p2, p);
            Vector3 dv = P3Sub(p1, p);
            *normal = V3Normalize(V3Cross(du, dv));
            ++normal;
        }
    }
    parg_buffer_unlock(surf->normals);

    surf->ntriangles = slices * stacks * 2;
    int indexCount = surf->ntriangles * 3;
    surf->indices = parg_buffer_alloc(indexCount * 2, PARG_GPU_ELEMENTS);
    uint16_t* index = (uint16_t*) parg_buffer_lock(surf->indices, PARG_WRITE);
    int v = 0;
    for (int i = 0; i < slices - 1; i++) {
        for (int j = 0; j < stacks; j++) {
            int next = (j + 1) % stacks;
            *index++ = v + next + stacks;
            *index++ = v + next;
            *index++ = v + j;
            *index++ = v + j;
            *index++ = v + j + stacks;
            *index++ = v + next + stacks;
        }
        v += stacks;
    }
    for (int j = 0; j < stacks; j++) {
        int next = (j + 1) % stacks;
        *index++ = next;
        *index++ = v + next;
        *index++ = v + j;
        *index++ = v + j;
        *index++ = j;
        *index++ = next;
    }
    parg_buffer_unlock(surf->indices);
    return surf;
}
Exemplo n.º 12
0
void PxcArticulationHelper::getImpulseSelfResponse(const PxcFsData& matrix,
												   PxU32 linkID0,
												   const PxcSIMDSpatial& impulse0,
												   PxcSIMDSpatial& deltaV0,
												   PxU32 linkID1,
												   const PxcSIMDSpatial& impulse1,
												   PxcSIMDSpatial& deltaV1)
{
	PX_ASSERT(linkID0 != linkID1);

	const PxcFsRow* rows = getFsRows(matrix);
	const PxcFsRowAux* aux = getAux(matrix);
	const PxcFsJointVectors* jointVectors = getJointVectors(matrix);

	PX_UNUSED(aux);

	PxcSIMDSpatial& dV0 = deltaV0, 
				  & dV1 = deltaV1;

	// standard case: parent-child limit
	if(matrix.parent[linkID1] == linkID0)
	{
		const PxcFsRow& r = rows[linkID1];
		const PxcFsJointVectors& j = jointVectors[linkID1];

		Vec3V lZ = V3Neg(impulse1.linear),
			  aZ = V3Neg(impulse1.angular);

		Vec3V sz = V3Add(aZ, V3Cross(lZ, j.jointOffset));
		
		lZ = V3Sub(lZ, V3ScaleAdd(r.DSI[0].linear, V3GetX(sz), V3ScaleAdd(r.DSI[1].linear, V3GetY(sz), V3Scale(r.DSI[2].linear, V3GetZ(sz)))));
		aZ = V3Sub(aZ, V3ScaleAdd(r.DSI[0].angular, V3GetX(sz), V3ScaleAdd(r.DSI[1].angular, V3GetY(sz), V3Scale(r.DSI[2].angular, V3GetZ(sz)))));

		aZ = V3Add(aZ, V3Cross(j.parentOffset, lZ));

		lZ = V3Sub(impulse0.linear, lZ);
		aZ = V3Sub(impulse0.angular, aZ);

		dV0 = getImpulseResponseSimd(matrix, linkID0, lZ, aZ);

		Vec3V aV = dV0.angular;
		Vec3V lV = V3Sub(dV0.linear, V3Cross(j.parentOffset, aV));

		Vec3V n = V3Add(V3Merge(V3Dot(r.DSI[0].linear, lV),  V3Dot(r.DSI[1].linear, lV),  V3Dot(r.DSI[2].linear, lV)),
						V3Merge(V3Dot(r.DSI[0].angular, aV), V3Dot(r.DSI[1].angular, aV), V3Dot(r.DSI[2].angular, aV)));

		n = V3Add(n, M33MulV3(r.D, sz));
		lV = V3Sub(lV, V3Cross(j.jointOffset, n));
		aV = V3Sub(aV, n);

		dV1 = PxcSIMDSpatial(lV, aV);
	}
	else
		getImpulseResponseSlow(matrix, linkID0, impulse0, deltaV0, linkID1, impulse1, deltaV1);

#if PXC_ARTICULATION_DEBUG_VERIFY
	PxcSIMDSpatial dV0_, dV1_;
	PxcFsGetImpulseSelfResponse(matrix, linkID0, impulse0, dV0_, linkID1, impulse1, dV1_);

	PX_ASSERT(almostEqual(dV0_, dV0, 1e-3f));
	PX_ASSERT(almostEqual(dV1_, dV1, 1e-3f));
#endif
}
Exemplo n.º 13
0
static MeshPod CreateTrefoil()
{
    const int Slices = 256;
    const int Stacks = 32;
    const int VertexCount = Slices * Stacks;
    const int IndexCount = VertexCount * 6;

    MeshPod mesh;
    glGenVertexArrays(1, &mesh.Vao);
    glBindVertexArray(mesh.Vao);

    // Create a buffer with interleaved positions and normals
    if (true) {
        Vertex verts[VertexCount];
        Vertex* pVert = &verts[0];
        float ds = 1.0f / Slices;
        float dt = 1.0f / Stacks;

        // The upper bounds in these loops are tweaked to reduce the
        // chance of precision error causing an incorrect # of iterations.
        for (float s = 0; s < 1 - ds / 2; s += ds) {
            for (float t = 0; t < 1 - dt / 2; t += dt) {
                const float E = 0.01f;
                Vector3 p = EvaluateTrefoil(s, t);
                Vector3 u = V3Sub(EvaluateTrefoil(s + E, t), p);
                Vector3 v = V3Sub(EvaluateTrefoil(s, t + E), p);
                Vector3 n = V3Normalize(V3Cross(u, v));
                pVert->Position = p;
                pVert->Normal = n;
                ++pVert;
            }
        }

        pezCheck(pVert - &verts[0] == VertexCount, "Tessellation error.");

        GLuint vbo;
        GLsizeiptr size = sizeof(verts);
        const GLvoid* data = &verts[0].Position.x;
        GLenum usage = GL_STATIC_DRAW;
        glGenBuffers(1, &vbo);
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        glBufferData(GL_ARRAY_BUFFER, size, data, usage);
    }

    // Create a buffer of 16-bit indices
    if (true) {
        GLushort inds[IndexCount];
        GLushort* pIndex = &inds[0];
        GLushort n = 0;
        for (GLushort i = 0; i < Slices; i++) {
            for (GLushort j = 0; j < Stacks; j++) {
                *pIndex++ = (n + j + Stacks) % VertexCount;
                *pIndex++ = n + (j + 1) % Stacks;
                *pIndex++ = n + j;
                
                *pIndex++ = (n + (j + 1) % Stacks + Stacks) % VertexCount;
                *pIndex++ = (n + (j + 1) % Stacks) % VertexCount;
                *pIndex++ = (n + j + Stacks) % VertexCount;
            }
            n += Stacks;
        }

        pezCheck(n == VertexCount, "Tessellation error.");
        pezCheck(pIndex - &inds[0] == IndexCount, "Tessellation error.");

        GLuint handle;
        GLsizeiptr size = sizeof(inds);
        const GLvoid* data = &inds[0];
        GLenum usage = GL_STATIC_DRAW;
        glGenBuffers(1, &handle);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, handle);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, size, data, usage);
    }

    mesh.VertexCount = VertexCount;
    mesh.IndexCount = IndexCount;

    glVertexAttribPointer(a("Position"), 3, GL_FLOAT, GL_FALSE, 24, 0);
    glVertexAttribPointer(a("Normal"), 3, GL_FLOAT, GL_FALSE, 24, offset(12));
    glEnableVertexAttribArray(a("Position"));
    glEnableVertexAttribArray(a("Normal"));

    pezCheck(OpenGLError);
    return mesh;
}
Exemplo n.º 14
0
void SetupColorTriangle(ColorTriangleData *tri)
{
	Vec3 V1, V2, N;
	double len;
	int i;

	/* Compute plane normal. */
	V1.x = tri->pts[3] - tri->pts[0];
	V2.x = tri->pts[6] - tri->pts[0];
	V1.y = tri->pts[4] - tri->pts[1];
	V2.y = tri->pts[7] - tri->pts[1];
	V1.z = tri->pts[5] - tri->pts[2];
	V2.z = tri->pts[8] - tri->pts[2];

	V3Cross(&N, &V1, &V2);
	V3Normalize(&N);
	tri->pnorm[0] = (float)N.x;
	tri->pnorm[1] = (float)N.y;
	tri->pnorm[2] = (float)N.z;

	/* Normalize the vertex normals. */
	for(i = 0; i < 9; i += 3)
	{
		if((tri->norms[i] * N.x +
        tri->norms[i+1] * N.y +
        tri->norms[i+2] * N.z) < 0.0)
		{
			tri->norms[i] = - tri->norms[i];
			tri->norms[i+1] = - tri->norms[i+1];
			tri->norms[i+2] = - tri->norms[i+2];
		}

		len = sqrt(tri->norms[i] * tri->norms[i] +
      tri->norms[i+1] * tri->norms[i+1] +
      tri->norms[i+2] * tri->norms[i+2]);
		if(len > EPSILON)
		{
			tri->norms[i] /= (float)len;
			tri->norms[i+1] /= (float)len;
			tri->norms[i+2] /= (float)len;
		}
		else   /* Use the plane normal for bad vertex normals. */
		{
			tri->norms[i] = (float)N.x;
			tri->norms[i+1] = (float)N.y;
			tri->norms[i+2] = (float)N.z;
		}
	}

	/* Determine axis of greatest projection. */
	if(fabs(N.x) > fabs(N.z))
	{
		if(fabs(N.x) > fabs(N.y))
			tri->axis = X_AXIS;
		else if(fabs(N.y) > fabs(N.z))
			tri->axis = Y_AXIS;
		else
			tri->axis = Z_AXIS;
	}
	else if(fabs(N.y) > fabs(N.z))
		tri->axis = Y_AXIS;
	else
		tri->axis = Z_AXIS;
}
Exemplo n.º 15
0
void eval_vcross(Expr *expr)
{
	expr->l->fn(expr->l);
	expr->r->fn(expr->r);
	V3Cross(&expr->v, &expr->l->v, &expr->r->v);
}
Exemplo n.º 16
0
/*
 * LoadSlopeInfo:  Load data for sloped surface descriptions and generate
 *   runtime representation of the data describing the texture coordinates.
 *   Return pointer to new SlopeData record on success, NULL on error
 */
SlopeData *LoadSlopeInfo(file_node *f) {
    int       size;
    long      txt_angle;
    long      index;
    SlopeData *new_slope;
    Vector3D  texture_orientation;
    Vector3D  v1,v2;
    char      junk[6];

    // create a new slope record
    size = sizeof(SlopeData);
    new_slope = (SlopeData *) SafeMalloc(size);
    memset(new_slope, 0, size);

    // load coefficients of plane equation
    if (CliMappedFileRead(f, &new_slope->plane.a, 4) != 4) return (SlopeData *)NULL;
    if (CliMappedFileRead(f, &new_slope->plane.b, 4) != 4) return (SlopeData *)NULL;
    if (CliMappedFileRead(f, &new_slope->plane.c, 4) != 4) return (SlopeData *)NULL;
    if (CliMappedFileRead(f, &new_slope->plane.d, 4) != 4) return (SlopeData *)NULL;

//    dprintf("loaded equation a = %d, b = %d, c = %d, d = %d\n", new_slope->plane.a, new_slope->plane.b, new_slope->plane.c, new_slope->plane.d);
    
    if (new_slope->plane.c == 0) {
	debug(("Error: loaded plane equation equal to a vertical slope\n"));
	// punt on error and stick in non crashing values (use assert instead?)
	new_slope->plane.a = 0;
	new_slope->plane.b = 0;
	new_slope->plane.c = 1024;
	new_slope->plane.d = 0;
    }
    
    // load x & y of texture origin
    if (CliMappedFileRead(f, &new_slope->p0.x, 4) != 4) return (SlopeData *)NULL;
    if (CliMappedFileRead(f, &new_slope->p0.y, 4) != 4) return (SlopeData *)NULL;
    
    // calculate z of texture origin from x, y, and plane equation
    new_slope->p0.z = (-new_slope->plane.a*new_slope->p0.x - new_slope->plane.b*new_slope->p0.y - new_slope->plane.d)/new_slope->plane.c;

    // load in texture angle - this is planar angle between x axis of texture & x axis of world
    if (CliMappedFileRead(f, &txt_angle, 4) != 4) return (SlopeData *)NULL;

	new_slope->texRot = txt_angle;
    
    // convert angle to vector
    texture_orientation.x = (long)Cos(txt_angle) >> 6;
    texture_orientation.y = (long)Sin(txt_angle) >> 6;
    texture_orientation.z = 0;

    // generate other endpoints from plane normal, texture origin, and texture
    //  orientation which determine the orientation of the texture's u v space
    //  in the 3d world's x, y, z space
    
    // cross normal with texture orientation to get vector perpendicular to texture
    //  orientation and normal = v axis direction
    V3Cross((Vector3D *)&(new_slope->plane), &texture_orientation, &v2);
    // scale to size of texture in world space
    V3Scale(&v2, FINENESS);
    
    // cross normal with v axis direction vector to get vector perpendicular to v axis
    //  and normal = u axis direction vector
    V3Cross(&v2, (Vector3D *)&(new_slope->plane), &v1);
    // scale to size of texture in world space
    V3Scale(&v1, FINENESS);

    // add vectors to origin to get endpoints
    V3Add(&new_slope->p0, &v1, &new_slope->p1);
    V3Add(&new_slope->p0, &v2, &new_slope->p2);

    // set flags indicating properties of the slope
    new_slope->flags = 0;

    if (ABS(new_slope->plane.c) < DIRECTIONAL_THRESHOLD)
	new_slope->flags |= SLF_DIRECTIONAL;
    else if (new_slope->plane.c < 0) // ceiling, apply same lighting hack as regular ceilings (see doDrawLeaf)
	new_slope->lightscale = FINENESS-(shade_amount>>1);
    else