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Cycles microdisplacement: Improved automatic bump mapping

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Object coordinates can now be used in the displacement shader and will give
correct results, where as before bump mapping was calculated from the displace
positions and resulted in incorrect shading.

This works by evaluating the shader in two parts, first bump then surface, and
setting the shader state to match what it would be if the surface was
undisplaced for the bump shader evaluation. Currently only `P` is set as if
undisplaced, but other shader variables could be set as well, such as `I` or
`time`. Since these aren't set to anything meaningful for displacement I left
them out of this patch, we can decide what to do with them separately.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D2156
This commit is contained in:
Mai Lavelle
2016-08-14 11:44:25 -04:00
parent 62aecbdac1
commit e7ea1ae78c
14 changed files with 181 additions and 52 deletions
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41
intern/cycles/kernel/osl/osl_shader.cpp
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@@ -184,6 +184,47 @@ void OSLShader::eval_surface(KernelGlobals *kg, ShaderData *sd, PathState *state
OSL::ShadingContext *octx = tdata->context[(int)ctx];
int shader = sd->shader & SHADER_MASK;
/* automatic bump shader */
if(kg->osl->bump_state[shader]) {
/* save state */
float3 P = sd->P;
float3 dPdx = sd->dP.dx;
float3 dPdy = sd->dP.dy;
/* set state as if undisplaced */
if(sd->flag & SD_HAS_DISPLACEMENT) {
float data[9];
bool found = kg->osl->services->get_attribute(sd, true, OSLRenderServices::u_empty, TypeDesc::TypeVector,
OSLRenderServices::u_geom_undisplaced, data);
assert(found);
memcpy(&sd->P, data, sizeof(float)*3);
memcpy(&sd->dP.dx, data+3, sizeof(float)*3);
memcpy(&sd->dP.dy, data+6, sizeof(float)*3);
object_position_transform(kg, sd, &sd->P);
object_dir_transform(kg, sd, &sd->dP.dx);
object_dir_transform(kg, sd, &sd->dP.dy);
globals->P = TO_VEC3(sd->P);
globals->dPdx = TO_VEC3(sd->dP.dx);
globals->dPdy = TO_VEC3(sd->dP.dy);
}
/* execute bump shader */
ss->execute(octx, *(kg->osl->bump_state[shader]), *globals);
/* reset state */
sd->P = P;
sd->dP.dx = dPdx;
sd->dP.dy = dPdy;
globals->P = TO_VEC3(P);
globals->dPdx = TO_VEC3(dPdx);
globals->dPdy = TO_VEC3(dPdy);
}
/* surface shader */
if(kg->osl->surface_state[shader]) {
ss->execute(octx, *(kg->osl->surface_state[shader]), *globals);
}