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Possible Adreno bug with uniform array
COR3 NDrive
Join Date: 1 Oct 10
Posts: 7
Posted: Tue, 2018-01-09 03:47
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I have the following uniform:

#define POLYLINE_SIZE 16

uniform highp vec2 u_polyline[POLYLINE_SIZE];

In the vertex shader I'm doing the following to interpolate a position between two points of the polyline:

vec2 pt1 = u_polyline[int(idx)];

vec2 pt2 = u_polyline[int(idx)+1];

vec2 pos = pt1 + (pt2 - pt1) * idx_diff;

On a Nexus 7 2nd Gen (Adreno 320), "pos" is incorrect, and is being calculated as if I was using pt2 instead of pt1 (but the direction is still correctly calculated between pt1 and pt2). So, for some reason the output is equivalent to:

vec2 pos = pt2 + (pt2 - pt1) * idx_diff;

Interestingly, if I change to the following, the "pos" is correct:

vec2 pos = u_polyline[int(idx)] + (pt2 - pt1) * idx_diff;

Is this a bug of the Adreno GPU?

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