mirror of
https://git.coom.tech/drummyfish/small3dlib.git
synced 2024-11-21 20:39:57 +01:00
Implement approximate PC (ugly)
This commit is contained in:
Miloslav Číž
parent
d1b20675d3
commit
15d17a9c02
2 changed files with 88 additions and 14 deletions
|
|
@ -11,7 +11,7 @@
|
|||
|
||||
#define S3L_FLAT 0
|
||||
#define S3L_STRICT_NEAR_CULLING 0
|
||||
#define S3L_PERSPECTIVE_CORRECTION 1
|
||||
#define S3L_PERSPECTIVE_CORRECTION 2
|
||||
#define S3L_SORT 2
|
||||
#define S3L_STENCIL_BUFFER 1
|
||||
#define S3L_Z_BUFFER 0
|
||||
|
|
|
|||
100
small3dlib.h
100
small3dlib.h
|
|
@ -177,11 +177,16 @@ typedef uint16_t S3L_Index;
|
|||
is an expensive operation! Possible values:
|
||||
|
||||
- 0: No perspective correction. Fastest, ugly.
|
||||
- 1: Per-pixel perspective correction, nice but very expensive.*/
|
||||
- 1: Per-pixel perspective correction, nice but very expensive.
|
||||
- 2: Approximation (computing only at every S3L_PC_APPROX_LENGTHth pixel). */
|
||||
|
||||
#define S3L_PERSPECTIVE_CORRECTION 0
|
||||
#endif
|
||||
|
||||
#ifndef S3L_PC_APPROX_LENGTH
|
||||
#define S3L_PC_APPROX_LENGTH 32
|
||||
#endif
|
||||
|
||||
#if S3L_PERSPECTIVE_CORRECTION
|
||||
#define S3L_COMPUTE_DEPTH 1 // PC inevitably computes depth, so enable it
|
||||
#endif
|
||||
|
|
@ -695,7 +700,7 @@ static inline int8_t S3L_stencilTest(
|
|||
#endif
|
||||
|
||||
#define S3L_COMPUTE_LERP_DEPTH\
|
||||
(S3L_COMPUTE_DEPTH && (S3L_PERSPECTIVE_CORRECTION != 1))
|
||||
(S3L_COMPUTE_DEPTH && (S3L_PERSPECTIVE_CORRECTION == 0))
|
||||
|
||||
#define S3L_SIN_TABLE_LENGTH 128
|
||||
|
||||
|
|
@ -1758,7 +1763,7 @@ void S3L_drawTriangle(
|
|||
initSide(r,t,r,1)
|
||||
initSide(l,t,l,1)
|
||||
|
||||
#if S3L_PERSPECTIVE_CORRECTION == 1
|
||||
#if S3L_PERSPECTIVE_CORRECTION != 0
|
||||
/* PC is done by linearly interpolating reciprocals from which the corrected
|
||||
velues can be computed. See
|
||||
http://www.lysator.liu.se/~mikaelk/doc/perspectivetexture/ */
|
||||
|
|
@ -1842,7 +1847,7 @@ void S3L_drawTriangle(
|
|||
#if !S3L_FLAT
|
||||
S3L_Unit rowLength = S3L_nonZero(rX - lX - 1); // prevent zero div
|
||||
|
||||
#if S3L_PERSPECTIVE_CORRECTION == 1
|
||||
#if S3L_PERSPECTIVE_CORRECTION != 0
|
||||
S3L_Unit lOverZ, lRecipZ, rOverZ, rRecipZ, lT, rT;
|
||||
|
||||
lT = S3L_getFastLerpValue(lSideFLS);
|
||||
|
|
@ -1869,6 +1874,7 @@ void S3L_drawTriangle(
|
|||
|
||||
b0FLS.stepScaled = rSideFLS.valueScaled / rowLength;
|
||||
b1FLS.stepScaled = -1 * lSideFLS.valueScaled / rowLength;
|
||||
|
||||
#endif
|
||||
#endif
|
||||
|
||||
|
|
@ -1881,7 +1887,7 @@ void S3L_drawTriangle(
|
|||
{
|
||||
lXClipped = 0;
|
||||
|
||||
#if S3L_PERSPECTIVE_CORRECTION != 1 && !S3L_FLAT
|
||||
#if S3L_PERSPECTIVE_CORRECTION == 0 && !S3L_FLAT
|
||||
b0FLS.valueScaled -= lX * b0FLS.stepScaled;
|
||||
b1FLS.valueScaled -= lX * b1FLS.stepScaled;
|
||||
|
||||
|
|
@ -1891,7 +1897,7 @@ void S3L_drawTriangle(
|
|||
#endif
|
||||
}
|
||||
|
||||
#if S3L_PERSPECTIVE_CORRECTION == 1
|
||||
#if S3L_PERSPECTIVE_CORRECTION != 0
|
||||
S3L_ScreenCoord i = lXClipped - lX; /* helper var to save one
|
||||
substraction in the inner
|
||||
loop */
|
||||
|
|
@ -1912,6 +1918,29 @@ void S3L_drawTriangle(
|
|||
|
||||
// draw the row -- inner loop:
|
||||
|
||||
#if S3L_PERSPECTIVE_CORRECTION == 2
|
||||
S3L_FastLerpState depthPC, b0PC, b1PC;
|
||||
|
||||
depthPC.valueScaled =
|
||||
((S3L_FRACTIONS_PER_UNIT * S3L_FRACTIONS_PER_UNIT) /
|
||||
S3L_nonZero(S3L_interpolate(lRecipZ,rRecipZ,i,rowLength)))
|
||||
<< S3L_FAST_LERP_QUALITY;
|
||||
|
||||
b0PC.valueScaled =
|
||||
(
|
||||
S3L_interpolateFrom0(rOverZ,i,rowLength)
|
||||
* depthPC.valueScaled
|
||||
) / S3L_FRACTIONS_PER_UNIT;
|
||||
|
||||
b1PC.valueScaled =
|
||||
(
|
||||
(lOverZ - S3L_interpolateFrom0(lOverZ,i,rowLength))
|
||||
* depthPC.valueScaled
|
||||
) / S3L_FRACTIONS_PER_UNIT;
|
||||
|
||||
int8_t rowCount = S3L_PC_APPROX_LENGTH;
|
||||
#endif
|
||||
|
||||
for (S3L_ScreenCoord x = lXClipped; x < rXClipped; ++x)
|
||||
{
|
||||
int8_t testsPassed = 1;
|
||||
|
|
@ -1926,6 +1955,42 @@ void S3L_drawTriangle(
|
|||
#if S3L_PERSPECTIVE_CORRECTION == 1
|
||||
p.depth = (S3L_FRACTIONS_PER_UNIT * S3L_FRACTIONS_PER_UNIT) /
|
||||
S3L_nonZero(S3L_interpolate(lRecipZ,rRecipZ,i,rowLength));
|
||||
#elif S3L_PERSPECTIVE_CORRECTION == 2
|
||||
if (rowCount >= S3L_PC_APPROX_LENGTH)
|
||||
{
|
||||
rowCount = 0;
|
||||
|
||||
S3L_Unit nextI = i + S3L_PC_APPROX_LENGTH;
|
||||
|
||||
S3L_Unit nextDepth =
|
||||
(
|
||||
(S3L_FRACTIONS_PER_UNIT * S3L_FRACTIONS_PER_UNIT) /
|
||||
S3L_nonZero(S3L_interpolate(lRecipZ,rRecipZ,nextI,rowLength))
|
||||
) << S3L_FAST_LERP_QUALITY;
|
||||
|
||||
depthPC.stepScaled =
|
||||
(nextDepth - depthPC.valueScaled) / S3L_PC_APPROX_LENGTH;
|
||||
|
||||
S3L_Unit nextValue =
|
||||
(
|
||||
S3L_interpolateFrom0(rOverZ,nextI,rowLength)
|
||||
* nextDepth
|
||||
) / S3L_FRACTIONS_PER_UNIT;
|
||||
|
||||
b0PC.stepScaled =
|
||||
(nextValue - b0PC.valueScaled) / S3L_PC_APPROX_LENGTH;
|
||||
|
||||
nextValue =
|
||||
(
|
||||
(lOverZ - S3L_interpolateFrom0(lOverZ,nextI,rowLength))
|
||||
* nextDepth
|
||||
) / S3L_FRACTIONS_PER_UNIT;
|
||||
|
||||
b1PC.stepScaled =
|
||||
(nextValue - b1PC.valueScaled) / S3L_PC_APPROX_LENGTH;
|
||||
}
|
||||
|
||||
p.depth = S3L_getFastLerpValue(depthPC);
|
||||
#else
|
||||
p.depth = S3L_getFastLerpValue(depthFLS);
|
||||
S3L_stepFastLerp(depthFLS);
|
||||
|
|
@ -1942,7 +2007,10 @@ void S3L_drawTriangle(
|
|||
if (testsPassed)
|
||||
{
|
||||
#if !S3L_FLAT
|
||||
#if S3L_PERSPECTIVE_CORRECTION == 1
|
||||
#if S3L_PERSPECTIVE_CORRECTION == 0
|
||||
*barycentric0 = S3L_getFastLerpValue(b0FLS);
|
||||
*barycentric1 = S3L_getFastLerpValue(b1FLS);
|
||||
#elif S3L_PERSPECTIVE_CORRECTION == 1
|
||||
*barycentric0 =
|
||||
(
|
||||
S3L_interpolateFrom0(rOverZ,i,rowLength)
|
||||
|
|
@ -1954,21 +2022,27 @@ void S3L_drawTriangle(
|
|||
(lOverZ - S3L_interpolateFrom0(lOverZ,i,rowLength))
|
||||
* p.depth
|
||||
) / S3L_FRACTIONS_PER_UNIT;
|
||||
#else
|
||||
*barycentric0 = S3L_getFastLerpValue(b0FLS);
|
||||
*barycentric1 = S3L_getFastLerpValue(b1FLS);
|
||||
#elif S3L_PERSPECTIVE_CORRECTION == 2
|
||||
*barycentric0 = S3L_getFastLerpValue(b0PC);
|
||||
*barycentric1 = S3L_getFastLerpValue(b1PC);
|
||||
#endif
|
||||
|
||||
*barycentric2 =
|
||||
S3L_FRACTIONS_PER_UNIT - *barycentric0 - *barycentric1;
|
||||
#endif
|
||||
|
||||
S3L_PIXEL_FUNCTION(&p);
|
||||
}
|
||||
|
||||
#if !S3L_FLAT
|
||||
#if S3L_PERSPECTIVE_CORRECTION == 1
|
||||
i++;
|
||||
#if S3L_PERSPECTIVE_CORRECTION != 0
|
||||
i++;
|
||||
#if S3L_PERSPECTIVE_CORRECTION == 2
|
||||
rowCount++;
|
||||
|
||||
S3L_stepFastLerp(depthPC);
|
||||
S3L_stepFastLerp(b0PC);
|
||||
S3L_stepFastLerp(b1PC);
|
||||
#endif
|
||||
#else
|
||||
S3L_stepFastLerp(b0FLS);
|
||||
S3L_stepFastLerp(b1FLS);
|
||||
|
|
|
|||
Loading…
Reference in a new issue