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Fix clipping errors when multiple strips submitted

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This commit is contained in:
Luke Benstead 2018-07-31 09:32:55 +01:00
parent a113722d82
commit 02b4b2d438
1 changed files with 20 additions and 4 deletions
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24
GL/clip.c
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@ -78,19 +78,27 @@ void clipTriangleStrip(AlignedVector* vertices, AlignedVector* outBuffer) {
*/
uint32_t i;
uint32_t stripCount = 2; /* The number of vertices in the source strip so far */
for(i = 2; i < vertices->size; ++i) {
if(stripCount < 2) {
stripCount++;
continue;
}
ClipVertex* thisVertex = aligned_vector_at(vertices, i);
ClipVertex* sourceTriangle[3] = {
aligned_vector_at(vertices, i - 2),
aligned_vector_at(vertices, i - 1),
aligned_vector_at(vertices, i)
thisVertex
};
/* If we're on an odd vertex, we need to swap the order of the first two vertices, as that's what
* triangle strips do */
uint8_t even = i % 2 == 0;
ClipVertex* v1 = even ? sourceTriangle[0] : sourceTriangle[1];
ClipVertex* v2 = even ? sourceTriangle[1] : sourceTriangle[0];
uint8_t swap = stripCount > 2 && (stripCount % 2 != 0);
ClipVertex* v1 = swap ? sourceTriangle[1] : sourceTriangle[0];
ClipVertex* v2 = swap ? sourceTriangle[0] : sourceTriangle[1];
ClipVertex* v3 = sourceTriangle[2];
uint8_t visible = ((v1->w > 0) ? 4 : 0) | ((v2->w > 0) ? 2 : 0) | ((v3->w > 0) ? 1 : 0);
@ -297,5 +305,13 @@ void clipTriangleStrip(AlignedVector* vertices, AlignedVector* outBuffer) {
aligned_vector_push_back(outBuffer, output, 4);
}
/* If this vertex was the last in the list, reset the stripCount */
if(thisVertex->flags == VERTEX_CMD_EOL) {
stripCount = 0;
} else {
stripCount++;
}
}
}