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DS GX: Add culling

This commit is contained in:
Vicki Pfau 2017-03-13 11:54:22 -07:00
parent 0e9e1a8dc4
commit 507a1c78e9
2 changed files with 50 additions and 0 deletions
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1
include/mgba/internal/ds/gx.h
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@ -177,6 +177,7 @@ struct DSGX {
struct DSGXPolygon* polygonBuffer[2];
struct DSGXVertex pendingVertices[8];
int pendingVertexIds[8];
bool reverseWinding;
uint16_t* tex[4];
uint16_t* texPal[6];

49
src/ds/gx.c
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@ -284,6 +284,48 @@ static bool _clipPolygon(struct DSGX* gx, struct DSGXPolygon* poly) {
int offscreenVerts[8] = { 0, 0, 0, 0 };
unsigned oldVerts[4];
int v;
if (!DSGXPolygonAttrsIsBackFace(poly->polyParams) || !DSGXPolygonAttrsIsFrontFace(poly->polyParams)) {
// Calculate normal direction
int nz = 0;
for (v = 0; v < poly->verts; ++v) {
struct DSGXVertex* v0 = &gx->pendingVertices[poly->vertIds[v]];
struct DSGXVertex* v1;
struct DSGXVertex* v2;
if (v < poly->verts - 2) {
v1 = &gx->pendingVertices[poly->vertIds[v + 1]];
v2 = &gx->pendingVertices[poly->vertIds[v + 2]];
} else if (v < poly->verts - 1) {
v1 = &gx->pendingVertices[poly->vertIds[v + 1]];
v2 = &gx->pendingVertices[poly->vertIds[v + 2 - poly->verts]];
} else {
v1 = &gx->pendingVertices[poly->vertIds[v + 1 - poly->verts]];
v2 = &gx->pendingVertices[poly->vertIds[v + 2 - poly->verts]];
}
int64_t vx1 = v0->vx - v1->vx;
int64_t vx2 = v2->vx - v1->vx;
int64_t vy1 = v0->vy - v1->vy;
int64_t vy2 = v2->vy - v1->vy;
int32_t vm1 = sqrt(vx1 * vx1 + vy1 * vy1);
int32_t vm2 = sqrt(vx2 * vx2 + vy2 * vy2);
if (vm1) {
vx1 = (vx1 << 8) / vm1;
vy1 = (vy1 << 8) / vm1;
}
if (vm2) {
vx2 = (vx2 << 8) / vm2;
vy2 = (vy2 << 8) / vm2;
}
nz += vx1 * vy2 - vy1 * vx2;
}
if (!DSGXPolygonAttrsIsBackFace(poly->polyParams) && nz < 0) {
return false;
}
if (!DSGXPolygonAttrsIsFrontFace(poly->polyParams) && nz > 0) {
return false;
}
}
// Collect offscreen vertices
for (v = 0; v < poly->verts; ++v) {
offscreenVerts[v] = _cohenSutherlandCode(gx, &gx->pendingVertices[poly->vertIds[v]]);
@ -638,6 +680,12 @@ static void _emitVertex(struct DSGX* gx, uint16_t x, uint16_t y, uint16_t z) {
gx->currentPoly.verts = 0;
break;
case 2:
// Reverse winding if needed
if (gx->reverseWinding) {
pbuf[gx->polygonIndex].vertIds[1] = gx->currentPoly.vertIds[2];
pbuf[gx->polygonIndex].vertIds[2] = gx->currentPoly.vertIds[1];
}
gx->reverseWinding = !gx->reverseWinding;
gx->currentPoly.vertIds[0] = gx->currentPoly.vertIds[1];
gx->currentPoly.vertIds[1] = gx->currentPoly.vertIds[2];
gx->currentPoly.verts = 2;
@ -1225,6 +1273,7 @@ static void _fifoRun(struct mTiming* timing, void* context, uint32_t cyclesLate)
case DS_GX_CMD_BEGIN_VTXS:
gx->vertexMode = entry.params[0] & 3;
gx->currentPoly = gx->nextPoly;
gx->reverseWinding = false;
memset(gx->pendingVertexIds, -1, sizeof(gx->pendingVertexIds));
break;
case DS_GX_CMD_END_VTXS: