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Add flat mode

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This commit is contained in:
Miloslav Číž 2019-06-01 23:21:44 +02:00
parent 40739dbb5e
commit 7c2e469516
2 changed files with 42 additions and 12 deletions
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41
small3dlib.h
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@ -171,6 +171,22 @@
#define S3L_COMPUTE_DEPTH 1 // PC inevitably computes depth, so enable it
#endif
#ifndef S3L_FLAT
#define S3L_FLAT 0 /**< If on, disables computation of per-pixel
values such as barycentric coordinates and
depth -- these will still be available but
will be the same for the whole triangle. This
can be used to create flat-shaded renders and
will be a lot faster. With this option on you
will probably want to use sorting instead of
z-buffer. */
#endif
#if S3L_FLAT
#define S3L_COMPUTE_DEPTH 0
#define S3L_PERSPECTIVE_CORRECTION 0
#endif
typedef int32_t S3L_Unit; /**< Units of measurement in 3D space. There is
S3L_FRACTIONS_PER_UNIT in one spatial unit.
By dividing the unit into fractions we
@ -1205,6 +1221,8 @@ void S3L_drawTriangle(
S3L_Vec4 *tPointPP, *lPointPP, *rPointPP; /* points in projction plane space
(in Units, normalized by
S3L_FRACTIONS_PER_UNIT) */
S3L_ScreenCoord x0, y0, x1, y1, x2, y2; /* points in screen space (pixel
coordinates) */
@ -1268,6 +1286,13 @@ void S3L_drawTriangle(
#undef assignPoints
#if S3L_FLAT
p.depth = (point0.z + point1.z + point2.z) / 3;
*barycentric0 = S3L_FRACTIONS_PER_UNIT / 3;
*barycentric1 = S3L_FRACTIONS_PER_UNIT / 3;
*barycentric2 = S3L_FRACTIONS_PER_UNIT - 2 * (S3L_FRACTIONS_PER_UNIT / 3);
#endif
p.triangleSize[0] = rPointSx - lPointSx;
p.triangleSize[1] = (rPointSy > lPointSy ? rPointSy : lPointSy) - tPointSy;
@ -1456,9 +1481,10 @@ void S3L_drawTriangle(
// draw the horizontal line
#if !S3L_FLAT
S3L_Unit rowLength = S3L_nonZero(rX - lX - 1); // prevent zero div
#if S3L_PERSPECTIVE_CORRECTION == 1
#if S3L_PERSPECTIVE_CORRECTION == 1
S3L_Unit lOverZ, lRecipZ, rOverZ, rRecipZ, lT, rT;
lT = S3L_getFastLerpValue(lSideFLS);
@ -1469,7 +1495,7 @@ void S3L_drawTriangle(
rOverZ = S3L_interpolateByUnitFrom0(rRecip1,rT);
rRecipZ = S3L_interpolateByUnit(rRecip0,rRecip1,rT);
#else
#else
S3L_FastLerpState b0FLS, b1FLS;
#if S3L_COMPUTE_LERP_DEPTH
@ -1485,6 +1511,7 @@ void S3L_drawTriangle(
b0FLS.stepScaled = rSideFLS.valueScaled / rowLength;
b1FLS.stepScaled = -1 * lSideFLS.valueScaled / rowLength;
#endif
#endif
// clip to the screen in x dimension:
@ -1496,7 +1523,7 @@ void S3L_drawTriangle(
{
lXClipped = 0;
#if S3L_PERSPECTIVE_CORRECTION != 1
#if S3L_PERSPECTIVE_CORRECTION != 1 && !S3L_FLAT
b0FLS.valueScaled -= lX * b0FLS.stepScaled;
b1FLS.valueScaled -= lX * b1FLS.stepScaled;
@ -1547,7 +1574,8 @@ void S3L_drawTriangle(
continue;
#endif
#if S3L_PERSPECTIVE_CORRECTION == 1
#if !S3L_FLAT
#if S3L_PERSPECTIVE_CORRECTION == 1
*barycentric0 =
(
S3L_interpolateFrom0(rOverZ,i,rowLength)
@ -1559,15 +1587,16 @@ void S3L_drawTriangle(
(lOverZ - S3L_interpolateFrom0(lOverZ,i,rowLength))
* p.depth
) / S3L_FRACTIONS_PER_UNIT;
#else
#else
*barycentric0 = S3L_getFastLerpValue(b0FLS);
*barycentric1 = S3L_getFastLerpValue(b1FLS);
S3L_stepFastLerp(b0FLS);
S3L_stepFastLerp(b1FLS);
#endif
#endif
*barycentric2 = S3L_FRACTIONS_PER_UNIT - *barycentric0 - *barycentric1;
#endif
S3L_PIXEL_FUNCTION(&p);
}

9
testSDL.c
View file

@ -10,10 +10,11 @@
//#define S3L_PRESET_HIGHEST_QUALITY
#define S3L_STRICT_NEAR_CULLING 0
#define S3L_PERSPECTIVE_CORRECTION 0
#define S3L_SORT 1
#define S3L_Z_BUFFER 0
#define S3L_FLAT 0
#define S3L_STRICT_NEAR_CULLING 1
#define S3L_PERSPECTIVE_CORRECTION 1
#define S3L_SORT 0
#define S3L_Z_BUFFER 1
#define S3L_PIXEL_FUNCTION drawPixel