Hello,

How can one get light's direction vector L in shader when computing shadowmap?

Trying to read this from illuminance loop, this doesn not work for me.
illuminance(P)
{
if( isshadowray() ){
printf(“L is: %d\n”, L);
}
}
This prints nothing.

Tried to make sort of custom illuminance loop, yet no luck.
lights = getlights(\“lightmask\”,_lightmask_,\“categories\”,_categories_);
if (setcurrentlight(lights)) {
if( isshadowray() ){
printf(“lights: %d\n”, lights);
}
}

The ‘lights’ array is empty in this case.

How can I read light's direction while computing shadow?

sergey_sh
Hello,

How can one get light's direction vector L in shader when computing shadowmap?

Shadow map is computed by a light acting as a camera. So light's direction is just -I.

Afaik in this mode mantra evaluates only opacity part of a surface shader, so it doesn't evaluate illuminance loop at all.

As to ray traced shadow “L” is the answer, but I think isshadowray() inside illuminance() evaluates always to 0, as shadow rays (see above) don't touch this loop.

thanks!

May I have a stupid question.

How can one get actual camera direction - the direction of camera from which final image is computed while shader is being called for deep shadows creation?

sergey_sh
How can one get actual camera direction - the direction of camera from which final image is computed while shader is being called for deep shadows creation?

…while shader is being called for deep shadow map creation? I don't think there is a way other than providing it by an user parameter to a shader. Mantra doesn't know the camera other than a light casting shadow during that stage. Divide and conquer.

Perhaps if you tell what is your goal, it will be easier to find a way.

SYmek, thanks for your reply.

Just need an angle between camera and light when mantra is creating deep shadow map. Looks like user parameter is the only solution.