Increase the subpixel precision to 8 bits. This requires
changing some of the code to 64 bits to avoid overflows.
Signed-off-by: Zack Rusin <za...@vmware.com>
---
tests/general/triangle-rasterization.cpp | 82 ++++++++++++++++----------------
1 file changed, 41 insertions(+), 41 deletions(-)
diff --git a/tests/general/triangle-rasterization.cpp
b/tests/general/triangle-rasterization.cpp
index 98fa959..2e4143f 100644
--- a/tests/general/triangle-rasterization.cpp
+++ b/tests/general/triangle-rasterization.cpp
@@ -103,7 +103,7 @@ static enum filling_convention_t {
} filling_convention;
/* Fixed point format */
-const int FIXED_SHIFT = 4;
+const int FIXED_SHIFT = 8;
const int FIXED_ONE = 1 << FIXED_SHIFT;
/* Default test size */
@@ -144,13 +144,13 @@ namespace std {
}
/* Proper rounding of float to integer */
-int iround(float v)
+int64_t iround(float v)
{
if (v > 0.0f)
v += 0.5f;
if (v < 0.0f)
v -= 0.5f;
- return (int)v;
+ return (int64_t)v;
}
/* Calculate log2 for integers */
@@ -169,56 +169,56 @@ void rast_triangle(uint8_t* buffer, uint32_t stride,
const Triangle& tri)
float center_offset = -0.5f;
/* 28.4 fixed point coordinates */
- int x1 = iround(FIXED_ONE * (tri[0].x + center_offset));
- int x2 = iround(FIXED_ONE * (tri[1].x + center_offset));
- int x3 = iround(FIXED_ONE * (tri[2].x + center_offset));
+ int64_t x1 = iround(FIXED_ONE * (tri[0].x + center_offset));
+ int64_t x2 = iround(FIXED_ONE * (tri[1].x + center_offset));
+ int64_t x3 = iround(FIXED_ONE * (tri[2].x + center_offset));
- int y1 = iround(FIXED_ONE * (tri[0].y + center_offset));
- int y2 = iround(FIXED_ONE * (tri[1].y + center_offset));
- int y3 = iround(FIXED_ONE * (tri[2].y + center_offset));
+ int64_t y1 = iround(FIXED_ONE * (tri[0].y + center_offset));
+ int64_t y2 = iround(FIXED_ONE * (tri[1].y + center_offset));
+ int64_t y3 = iround(FIXED_ONE * (tri[2].y + center_offset));
/* Force correct vertex order */
- const int cross = (x2 - x1) * (y3 - y2) - (y2 - y1) * (x3 - x2);
+ const int64_t cross = (x2 - x1) * (y3 - y2) - (y2 - y1) * (x3 - x2);
if (cross > 0) {
std::swap(x1, x3);
std::swap(y1, y3);
}
/* Deltas */
- const int dx12 = x1 - x2;
- const int dx23 = x2 - x3;
- const int dx31 = x3 - x1;
+ const int64_t dx12 = x1 - x2;
+ const int64_t dx23 = x2 - x3;
+ const int64_t dx31 = x3 - x1;
- const int dy12 = y1 - y2;
- const int dy23 = y2 - y3;
- const int dy31 = y3 - y1;
+ const int64_t dy12 = y1 - y2;
+ const int64_t dy23 = y2 - y3;
+ const int64_t dy31 = y3 - y1;
/* Fixed-point deltas */
- const int fdx12 = dx12 << FIXED_SHIFT;
- const int fdx23 = dx23 << FIXED_SHIFT;
- const int fdx31 = dx31 << FIXED_SHIFT;
+ const int64_t fdx12 = dx12 << FIXED_SHIFT;
+ const int64_t fdx23 = dx23 << FIXED_SHIFT;
+ const int64_t fdx31 = dx31 << FIXED_SHIFT;
- const int fdy12 = dy12 << FIXED_SHIFT;
- const int fdy23 = dy23 << FIXED_SHIFT;
- const int fdy31 = dy31 << FIXED_SHIFT;
+ const int64_t fdy12 = dy12 << FIXED_SHIFT;
+ const int64_t fdy23 = dy23 << FIXED_SHIFT;
+ const int64_t fdy31 = dy31 << FIXED_SHIFT;
/* Bounding rectangle */
- int minx = std::min(x1, x2, x3) >> FIXED_SHIFT;
- int maxx = (std::max(x1, x2, x3)) >> FIXED_SHIFT;
+ int64_t minx = std::min(x1, x2, x3) >> FIXED_SHIFT;
+ int64_t maxx = (std::max(x1, x2, x3)) >> FIXED_SHIFT;
- int miny = (std::min(y1, y2, y3)) >> FIXED_SHIFT;
- int maxy = std::max(y1, y2, y3) >> FIXED_SHIFT;
+ int64_t miny = (std::min(y1, y2, y3)) >> FIXED_SHIFT;
+ int64_t maxy = std::max(y1, y2, y3) >> FIXED_SHIFT;
- minx = std::max(minx, 0);
- maxx = std::min(maxx, fbo_width - 1);
+ minx = std::max(minx, (int64_t)0);
+ maxx = std::min(maxx, (int64_t)fbo_width - 1);
- miny = std::max(miny, 0);
- maxy = std::min(maxy, fbo_height - 1);
+ miny = std::max(miny, (int64_t)0);
+ maxy = std::min(maxy, (int64_t)fbo_height - 1);
/* Half-edge constants */
- int c1 = dy12 * x1 - dx12 * y1;
- int c2 = dy23 * x2 - dx23 * y2;
- int c3 = dy31 * x3 - dx31 * y3;
+ int64_t c1 = dy12 * x1 - dx12 * y1;
+ int64_t c2 = dy23 * x2 - dx23 * y2;
+ int64_t c3 = dy31 * x3 - dx31 * y3;
/* Correct for filling convention */
switch (filling_convention) {
@@ -264,18 +264,18 @@ void rast_triangle(uint8_t* buffer, uint32_t stride,
const Triangle& tri)
break;
}
- int cy1 = c1 + dx12 * (miny << FIXED_SHIFT) - dy12 * (minx <<
FIXED_SHIFT);
- int cy2 = c2 + dx23 * (miny << FIXED_SHIFT) - dy23 * (minx <<
FIXED_SHIFT);
- int cy3 = c3 + dx31 * (miny << FIXED_SHIFT) - dy31 * (minx <<
FIXED_SHIFT);
+ int64_t cy1 = c1 + dx12 * (miny << FIXED_SHIFT) - dy12 * (minx <<
FIXED_SHIFT);
+ int64_t cy2 = c2 + dx23 * (miny << FIXED_SHIFT) - dy23 * (minx <<
FIXED_SHIFT);
+ int64_t cy3 = c3 + dx31 * (miny << FIXED_SHIFT) - dy31 * (minx <<
FIXED_SHIFT);
/* Perform rasterization */
buffer += miny * stride;
- for (int y = miny; y <= maxy; y++) {
- int cx1 = cy1;
- int cx2 = cy2;
- int cx3 = cy3;
+ for (int64_t y = miny; y <= maxy; y++) {
+ int64_t cx1 = cy1;
+ int64_t cx2 = cy2;
+ int64_t cx3 = cy3;
- for (int x = minx; x <= maxx; x++) {
+ for (int64_t x = minx; x <= maxx; x++) {
if (cx1 > 0 && cx2 > 0 && cx3 > 0) {
((uint32_t*)buffer)[x] = 0x00FF00FF;
}
--
1.8.3.2
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