kernel_triangle.h

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/*
 * Copyright 2011, Blender Foundation.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

CCL_NAMESPACE_BEGIN

/* Point on triangle for Moller-Trumbore triangles */
__device_inline float3 triangle_point_MT(KernelGlobals *kg, int tri_index, float u, float v)
{
    /* load triangle vertices */
    float3 tri_vindex = float4_to_float3(kernel_tex_fetch(__tri_vindex, tri_index));

    float3 v0 = float4_to_float3(kernel_tex_fetch(__tri_verts, __float_as_int(tri_vindex.x)));
    float3 v1 = float4_to_float3(kernel_tex_fetch(__tri_verts, __float_as_int(tri_vindex.y)));
    float3 v2 = float4_to_float3(kernel_tex_fetch(__tri_verts, __float_as_int(tri_vindex.z)));

    /* compute point */
    float t = 1.0f - u - v;
    return (u*v0 + v*v1 + t*v2);
}

/* Sample point on triangle */
__device_inline float3 triangle_sample_MT(KernelGlobals *kg, int tri_index, float randu, float randv)
{
    /* compute point */
    randu = sqrtf(randu);

    float u = 1.0f - randu;
    float v = randv*randu;

    return triangle_point_MT(kg, tri_index, u, v);
}

/* Normal for Moller-Trumbore triangles */
__device_inline float3 triangle_normal_MT(KernelGlobals *kg, int tri_index, int *shader)
{
#if 0
    /* load triangle vertices */
    float3 tri_vindex = float4_to_float3(kernel_tex_fetch(__tri_vindex, tri_index));

    float3 v0 = float4_to_float3(kernel_tex_fetch(__tri_verts, __float_as_int(tri_vindex.x)));
    float3 v1 = float4_to_float3(kernel_tex_fetch(__tri_verts, __float_as_int(tri_vindex.y)));
    float3 v2 = float4_to_float3(kernel_tex_fetch(__tri_verts, __float_as_int(tri_vindex.z)));

    /* compute normal */
    return normalize(cross(v2 - v0, v1 - v0));
#else
    float4 Nm = kernel_tex_fetch(__tri_normal, tri_index);
    *shader = __float_as_int(Nm.w);
    return make_float3(Nm.x, Nm.y, Nm.z);
#endif
}

__device_inline float3 triangle_smooth_normal(KernelGlobals *kg, int tri_index, float u, float v)
{
    /* load triangle vertices */
    float3 tri_vindex = float4_to_float3(kernel_tex_fetch(__tri_vindex, tri_index));

    float3 n0 = float4_to_float3(kernel_tex_fetch(__tri_vnormal, __float_as_int(tri_vindex.x)));
    float3 n1 = float4_to_float3(kernel_tex_fetch(__tri_vnormal, __float_as_int(tri_vindex.y)));
    float3 n2 = float4_to_float3(kernel_tex_fetch(__tri_vnormal, __float_as_int(tri_vindex.z)));

    return normalize((1.0f - u - v)*n2 + u*n0 + v*n1);
}

__device_inline void triangle_dPdudv(KernelGlobals *kg, float3 *dPdu, float3 *dPdv, int tri)
{
    /* fetch triangle vertex coordinates */
    float3 tri_vindex = float4_to_float3(kernel_tex_fetch(__tri_vindex, tri));

    float3 p0 = float4_to_float3(kernel_tex_fetch(__tri_verts, __float_as_int(tri_vindex.x)));
    float3 p1 = float4_to_float3(kernel_tex_fetch(__tri_verts, __float_as_int(tri_vindex.y)));
    float3 p2 = float4_to_float3(kernel_tex_fetch(__tri_verts, __float_as_int(tri_vindex.z)));

    /* compute derivatives of P w.r.t. uv */
    *dPdu = (p0 - p2);
    *dPdv = (p1 - p2);
}

/* attributes */

__device float triangle_attribute_float(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int offset, float *dx, float *dy)
{
    if(elem == ATTR_ELEMENT_FACE) {
        if(dx) *dx = 0.0f;
        if(dy) *dy = 0.0f;

        return kernel_tex_fetch(__attributes_float, offset + sd->prim);
    }
    else if(elem == ATTR_ELEMENT_VERTEX) {
        float3 tri_vindex = float4_to_float3(kernel_tex_fetch(__tri_vindex, sd->prim));

        float f0 = kernel_tex_fetch(__attributes_float, offset + __float_as_int(tri_vindex.x));
        float f1 = kernel_tex_fetch(__attributes_float, offset + __float_as_int(tri_vindex.y));
        float f2 = kernel_tex_fetch(__attributes_float, offset + __float_as_int(tri_vindex.z));

#ifdef __RAY_DIFFERENTIALS__
        if(dx) *dx = sd->du.dx*f0 + sd->dv.dx*f1 - (sd->du.dx + sd->dv.dx)*f2;
        if(dy) *dy = sd->du.dy*f0 + sd->dv.dy*f1 - (sd->du.dy + sd->dv.dy)*f2;
#endif

        return sd->u*f0 + sd->v*f1 + (1.0f - sd->u - sd->v)*f2;
    }
    else if(elem == ATTR_ELEMENT_CORNER) {
        int tri = offset + sd->prim*3;
        float f0 = kernel_tex_fetch(__attributes_float, tri + 0);
        float f1 = kernel_tex_fetch(__attributes_float, tri + 1);
        float f2 = kernel_tex_fetch(__attributes_float, tri + 2);

#ifdef __RAY_DIFFERENTIALS__
        if(dx) *dx = sd->du.dx*f0 + sd->dv.dx*f1 - (sd->du.dx + sd->dv.dx)*f2;
        if(dy) *dy = sd->du.dy*f0 + sd->dv.dy*f1 - (sd->du.dy + sd->dv.dy)*f2;
#endif

        return sd->u*f0 + sd->v*f1 + (1.0f - sd->u - sd->v)*f2;
    }
    else {
        if(dx) *dx = 0.0f;
        if(dy) *dy = 0.0f;

        return 0.0f;
    }
}

__device float3 triangle_attribute_float3(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int offset, float3 *dx, float3 *dy)
{
    if(elem == ATTR_ELEMENT_FACE) {
        if(dx) *dx = make_float3(0.0f, 0.0f, 0.0f);
        if(dy) *dy = make_float3(0.0f, 0.0f, 0.0f);

        return float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + sd->prim));
    }
    else if(elem == ATTR_ELEMENT_VERTEX) {
        float3 tri_vindex = float4_to_float3(kernel_tex_fetch(__tri_vindex, sd->prim));

        float3 f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + __float_as_int(tri_vindex.x)));
        float3 f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + __float_as_int(tri_vindex.y)));
        float3 f2 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + __float_as_int(tri_vindex.z)));

#ifdef __RAY_DIFFERENTIALS__
        if(dx) *dx = sd->du.dx*f0 + sd->dv.dx*f1 - (sd->du.dx + sd->dv.dx)*f2;
        if(dy) *dy = sd->du.dy*f0 + sd->dv.dy*f1 - (sd->du.dy + sd->dv.dy)*f2;
#endif

        return sd->u*f0 + sd->v*f1 + (1.0f - sd->u - sd->v)*f2;
    }
    else if(elem == ATTR_ELEMENT_CORNER) {
        int tri = offset + sd->prim*3;
        float3 f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, tri + 0));
        float3 f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, tri + 1));
        float3 f2 = float4_to_float3(kernel_tex_fetch(__attributes_float3, tri + 2));

#ifdef __RAY_DIFFERENTIALS__
        if(dx) *dx = sd->du.dx*f0 + sd->dv.dx*f1 - (sd->du.dx + sd->dv.dx)*f2;
        if(dy) *dy = sd->du.dy*f0 + sd->dv.dy*f1 - (sd->du.dy + sd->dv.dy)*f2;
#endif

        return sd->u*f0 + sd->v*f1 + (1.0f - sd->u - sd->v)*f2;
    }
    else {
        if(dx) *dx = make_float3(0.0f, 0.0f, 0.0f);
        if(dy) *dy = make_float3(0.0f, 0.0f, 0.0f);

        return make_float3(0.0f, 0.0f, 0.0f);
    }
}

CCL_NAMESPACE_END