alpha channel set problem in PrPro plugin

Report · Apr 09, 2021

Dear AE fellows,

I use cairo to draw a animated shape on the sequence.

The converting function works corrrectly in AE giving correct color and transparent background.

Used as is for PrPro it gives black background instead.

Could you explain why this is happening?

Here is my code:

struct cairoRefcon
{
PF_EffectWorld output;
unsigned char* data;
int stride;
};


PF_Pixel* sampleIntegral8(PF_EffectWorld& def, int x, int y) {
return (PF_Pixel*)((char*)def.data +
(y * def.rowbytes) +
(x * sizeof(PF_Pixel)));
}


PF_Err cairoCopy8(void* refcon, A_long threadInd, A_long iterNum, A_long iterTotal)
{
cairoRefcon* data = (cairoRefcon*)refcon;

int i = iterNum;

PF_Err err = PF_Err_NONE;

uint32_t* rowP;

PF_Pixel8* worldPtr = sampleIntegral8(data->output, 0, i);

rowP = (uint32_t*)(data->data + i * data->stride);

for (int x = 0; x < data->output.width; x++)// column
{



worldPtr->alpha = rowP[x] >> 24;
if (worldPtr->alpha)
{
float rf = A_u_char(rowP[x] >> 16) / (float)worldPtr->alpha;
float gf = A_u_char(rowP[x] >> 8) / (float)worldPtr->alpha;
float bf = A_u_char(rowP[x] >> 0) / (float)worldPtr->alpha;
worldPtr->red = A_u_char(rf * PF_MAX_CHAN8);
worldPtr->green = A_u_char(gf * PF_MAX_CHAN8);
worldPtr->blue = A_u_char(bf * PF_MAX_CHAN8);
}
else {
worldPtr->alpha = A_u_char(0. * PF_MAX_CHAN8);
float rf = A_u_char(rowP[x] >> 16);
float gf = A_u_char(rowP[x] >> 8);
float bf = A_u_char(rowP[x] >> 0);
worldPtr->red = A_u_char(1. * PF_MAX_CHAN8);
worldPtr->green = A_u_char(1. * PF_MAX_CHAN8);
worldPtr->blue = A_u_char(1. * PF_MAX_CHAN8);

}


worldPtr++;
}

return err;
}

Report · Apr 09, 2021

How do you mean used in ppro? If it's ok in Ae why don't you render it with transparency then import to premiere? If in Premiere you don't see transparent checkerboard just set it in the wrench menu in the program monitot

Report · Apr 13, 2021

Dear Roei, thanks for the answer.

Eventually, I imported the canvas on which I draw with

PF_EffectWorld *inputP = &(params[MYPLUGIN_INPUT]->u.ld);

And then I blended it with my plugin animated shape.

Y.