Revert "sw_engine: replaced texture mapping AA with 4x sampling interp"

This reverts commit 174fae9089.

Will revisit this since the quality is too poor...

src/renderer/sw_engine/tvgSwRasterTexmap.h

@@ -33,7 +33,9 @@ struct Polygon
 
 struct AALine
 {
-   uint16_t x[2];
+   int32_t x[2];
+   int32_t coverage[2];
+   int32_t length[2];
 };
 
 struct AASpans
@@ -88,8 +90,8 @@ static void _rasterBlendingPolygonImageSegment(SwSurface* surface, const SwImage
         //Anti-Aliasing frames
         if (aaSpans) {
             ay = y - aaSpans->yStart;
-            if (aaSpans->lines[ay].x[0] > x1) aaSpans->lines[ay].x[0] = static_cast<uint16_t>(x1);
+            if (aaSpans->lines[ay].x[0] > x1) aaSpans->lines[ay].x[0] = x1;
-            if (aaSpans->lines[ay].x[1] < x2) aaSpans->lines[ay].x[1] = static_cast<uint16_t>(x2);
+            if (aaSpans->lines[ay].x[1] < x2) aaSpans->lines[ay].x[1] = x2;
         }
 
         //Range allowed
@@ -190,8 +192,8 @@ static void _rasterPolygonImageSegment(SwSurface* surface, const SwImage& image,
         //Anti-Aliasing frames
         if (aaSpans) {
             ay = y - aaSpans->yStart;
-            if (aaSpans->lines[ay].x[0] > x1) aaSpans->lines[ay].x[0] = static_cast<uint16_t>(x1);
+            if (aaSpans->lines[ay].x[0] > x1) aaSpans->lines[ay].x[0] = x1;
-            if (aaSpans->lines[ay].x[1] < x2) aaSpans->lines[ay].x[1] = static_cast<uint16_t>(x2);
+            if (aaSpans->lines[ay].x[1] < x2) aaSpans->lines[ay].x[1] = x2;
         }
 
         //Range allowed
@@ -217,7 +219,6 @@ static void _rasterPolygonImageSegment(SwSurface* surface, const SwImage& image,
 
                 ar = _modf(u);
                 ab = _modf(v);
-
                 iru = uu + 1;
                 irv = vv + 1;
 
@@ -463,40 +464,243 @@ static AASpans* _AASpans(int yStart, int yEnd)
     aaSpans->lines = tvg::malloc<AALine*>(height * sizeof(AALine));
 
     for (int32_t i = 0; i < height; i++) {
-        aaSpans->lines[i].x[0] = UINT16_MAX;
+        aaSpans->lines[i].x[0] = INT32_MAX;
         aaSpans->lines[i].x[1] = 0;
+        aaSpans->lines[i].length[0] = 0;
+        aaSpans->lines[i].length[1] = 0;
     }
     return aaSpans;
 }
 
 
+static void _calcIrregularCoverage(AALine* lines, int32_t eidx, int32_t y, int32_t diagonal, int32_t edgeDist, bool reverse)
+{
+    if (eidx == 1) reverse = !reverse;
+    int32_t coverage = (255 / (diagonal + 2));
+    int32_t tmp;
+    for (int32_t ry = 0; ry < (diagonal + 2); ry++) {
+        tmp = y - ry - edgeDist;
+        if (tmp < 0) return;
+        lines[tmp].length[eidx] = 1;
+        if (reverse) lines[tmp].coverage[eidx] = 255 - (coverage * ry);
+        else lines[tmp].coverage[eidx] = (coverage * ry);
+    }
+}
+
+
+static void _calcVertCoverage(AALine *lines, int32_t eidx, int32_t y, int32_t rewind, bool reverse)
+{
+    if (eidx == 1) reverse = !reverse;
+    int32_t coverage = (255 / (rewind + 1));
+    int32_t tmp;
+    for (int ry = 1; ry < (rewind + 1); ry++) {
+        tmp = y - ry;
+        if (tmp < 0) return;
+        lines[tmp].length[eidx] = 1;
+        if (reverse) lines[tmp].coverage[eidx] = (255 - (coverage * ry));
+        else lines[tmp].coverage[eidx] = (coverage * ry);
+    }
+}
+
+
+static void _calcHorizCoverage(AALine *lines, int32_t eidx, int32_t y, int32_t x, int32_t x2)
+{
+    lines[y].length[eidx] = abs(x - x2);
+    lines[y].coverage[eidx] = (255 / (lines[y].length[eidx] + 1));
+}
+
+
+/*
+ * This Anti-Aliasing mechanism is originated from Hermet Park's idea.
+ * To understand this AA logic, you can refer this page:
+ * https://uigraphics.tistory.com/1
+*/
+static void _calcAAEdge(AASpans *aaSpans, int32_t eidx)
+{
+//Previous edge direction:
+#define DirOutHor 0x0011
+#define DirOutVer 0x0001
+#define DirInHor  0x0010
+#define DirInVer  0x0000
+#define DirNone   0x1000
+
+#define PUSH_VERTEX() \
+    do { \
+        pEdge.x = lines[y].x[eidx]; \
+        pEdge.y = y; \
+        ptx[0] = tx[0]; \
+        ptx[1] = tx[1]; \
+    } while (0)
+
+    int32_t y = 0;
+    SwPoint pEdge = {-1, -1};       //previous edge point
+    SwPoint edgeDiff = {0, 0};      //temporary used for point distance
+
+    /* store bigger to tx[0] between prev and current edge's x positions. */
+    int32_t tx[2] = {0, 0};
+    /* back up prev tx values */
+    int32_t ptx[2] = {0, 0};
+    int32_t diagonal = 0;           //straight diagonal pixels count
+
+    auto yStart = aaSpans->yStart;
+    auto yEnd = aaSpans->yEnd;
+    auto lines = aaSpans->lines;
+
+    int32_t prevDir = DirNone;
+    int32_t curDir = DirNone;
+
+    yEnd -= yStart;
+
+    //Start Edge
+    if (y < yEnd) {
+        pEdge.x = lines[y].x[eidx];
+        pEdge.y = y;
+    }
+
+    //Calculates AA Edges
+    for (y++; y < yEnd; y++) {
+
+        if (lines[y].x[0] == INT32_MAX) continue;
+
+        //Ready tx
+        if (eidx == 0) {
+            tx[0] = pEdge.x;
+            tx[1] = lines[y].x[0];
+        } else {
+            tx[0] = lines[y].x[1];
+            tx[1] = pEdge.x;
+        }
+        edgeDiff.x = (tx[0] - tx[1]);
+        edgeDiff.y = (y - pEdge.y);
+
+        //Confirm current edge direction
+        if (edgeDiff.x > 0) {
+            if (edgeDiff.y == 1) curDir = DirOutHor;
+            else curDir = DirOutVer;
+        } else if (edgeDiff.x < 0) {
+            if (edgeDiff.y == 1) curDir = DirInHor;
+            else curDir = DirInVer;
+        } else curDir = DirNone;
+
+        //straight diagonal increase
+        if ((curDir == prevDir) && (y < yEnd)) {
+            if ((abs(edgeDiff.x) == 1) && (edgeDiff.y == 1)) {
+                ++diagonal;
+                PUSH_VERTEX();
+                continue;
+            }
+        }
+
+        switch (curDir) {
+            case DirOutHor: {
+                _calcHorizCoverage(lines, eidx, y, tx[0], tx[1]);
+                if (diagonal > 0) {
+                    _calcIrregularCoverage(lines, eidx, y, diagonal, 0, true);
+                    diagonal = 0;
+                }
+               /* Increment direction is changed: Outside Vertical -> Outside Horizontal */
+               if (prevDir == DirOutVer) _calcHorizCoverage(lines, eidx, pEdge.y, ptx[0], ptx[1]);
+
+               //Trick, but fine-tunning!
+               if (y == 1) _calcHorizCoverage(lines, eidx, pEdge.y, tx[0], tx[1]);
+               PUSH_VERTEX();
+            }
+            break;
+            case DirOutVer: {
+                _calcVertCoverage(lines, eidx, y, edgeDiff.y, true);
+                if (diagonal > 0) {
+                    _calcIrregularCoverage(lines, eidx, y, diagonal, edgeDiff.y, false);
+                    diagonal = 0;
+                }
+               /* Increment direction is changed: Outside Horizontal -> Outside Vertical */
+               if (prevDir == DirOutHor) _calcHorizCoverage(lines, eidx, pEdge.y, ptx[0], ptx[1]);
+               PUSH_VERTEX();
+            }
+            break;
+            case DirInHor: {
+                _calcHorizCoverage(lines, eidx, (y - 1), tx[0], tx[1]);
+                if (diagonal > 0) {
+                    _calcIrregularCoverage(lines, eidx, y, diagonal, 0, false);
+                    diagonal = 0;
+                }
+                /* Increment direction is changed: Outside Horizontal -> Inside Horizontal */
+               if (prevDir == DirOutHor) _calcHorizCoverage(lines, eidx, pEdge.y, ptx[0], ptx[1]);
+               PUSH_VERTEX();
+            }
+            break;
+            case DirInVer: {
+                _calcVertCoverage(lines, eidx, y, edgeDiff.y, false);
+                if (prevDir == DirOutHor) edgeDiff.y -= 1;      //Weird, fine tuning?????????????????????
+                if (diagonal > 0) {
+                    _calcIrregularCoverage(lines, eidx, y, diagonal, edgeDiff.y, true);
+                    diagonal = 0;
+                }
+                /* Increment direction is changed: Outside Horizontal -> Inside Vertical */
+                if (prevDir == DirOutHor) _calcHorizCoverage(lines, eidx, pEdge.y, ptx[0], ptx[1]);
+                PUSH_VERTEX();
+            }
+            break;
+        }
+        if (curDir != DirNone) prevDir = curDir;
+    }
+
+    //leftovers...?
+    if ((edgeDiff.y == 1) && (edgeDiff.x != 0)) {
+        if (y >= yEnd) y = (yEnd - 1);
+        _calcHorizCoverage(lines, eidx, y - 1, ptx[0], ptx[1]);
+        _calcHorizCoverage(lines, eidx, y, tx[0], tx[1]);
+    } else {
+        ++y;
+        if (y > yEnd) y = yEnd;
+        _calcVertCoverage(lines, eidx, y, (edgeDiff.y + 1), (prevDir & 0x00000001));
+    }
+}
+
+
 static void _apply(SwSurface* surface, AASpans* aaSpans)
 {
+    auto end = surface->buf32 + surface->h * surface->stride;
     auto buf = surface->buf32 + surface->stride * aaSpans->yStart;
-    auto w = int32_t(surface->w - 1);
-    auto h = int32_t(surface->h - 1);
     auto y = aaSpans->yStart;
     auto line = aaSpans->lines;
+    uint32_t pix;
+    uint32_t* dst;
+    int32_t pos;
 
-    constexpr int WEIGHT = 190;
+   _calcAAEdge(aaSpans, 0);    //left side
-
+   _calcAAEdge(aaSpans, 1);    //right side
-    auto feathering = [&](pixel_t* dst, int32_t x) {
-        if (y > 0) {
-            auto top = dst - surface->stride;
-            if (x < w) *dst = INTERPOLATE(*dst, *(top + 1), WEIGHT);
-            if (x > 0) *dst = INTERPOLATE(*dst, *(top - 1), WEIGHT);
-        }
-        if (y < h) {
-            auto bottom = dst + surface->stride;
-            if (x < w) *dst = INTERPOLATE(*dst, *(bottom + 1), WEIGHT);
-            if (x > 0) *dst = INTERPOLATE(*dst, *(bottom - 1), WEIGHT);
-        }
-    };
 
     while (y < aaSpans->yEnd) {
         if (line->x[1] - line->x[0] > 0) {
-            feathering(buf + line->x[0], line->x[0]);  //left
+            //Left edge
-            feathering(buf + line->x[1] - 1, line->x[1] - 1);  //right
+            dst = buf + line->x[0];
+            pix = *(dst - ((line->x[0] > 1) ? 1 : 0));
+            pos = 1;
+
+            //exceptional handling. out of memory bound.
+            if (dst + line->length[0] >= end) {
+                pos += (dst + line->length[0] - end);
+            }
+
+            while (pos <= line->length[0]) {
+                *dst = INTERPOLATE(*dst, pix, line->coverage[0] * pos);
+                ++dst;
+                ++pos;
+            }
+
+            //Right edge
+            dst = buf + line->x[1] - 1;
+            pix = *(dst + (line->x[1] < (int32_t)(surface->w - 1) ? 1 : 0));
+            pos = line->length[1];
+
+            //exceptional handling. out of memory bound.
+            if (dst - pos < surface->buf32) --pos;
+
+            while (pos > 0) {
+                *dst = INTERPOLATE(*dst, pix, 255 - (line->coverage[1] * pos));
+                --dst;
+                --pos;
+            }
         }
         buf += surface->stride;
         ++line;