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Add doom style column clipping to triangle drawer

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This commit is contained in:
Magnus Norddahl 2016-10-19 15:43:10 +02:00
parent 6a7bb43ce1
commit ea72152c31
1 changed files with 36 additions and 9 deletions
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45
src/r_draw_rgba.cpp
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@ -1281,7 +1281,7 @@ float grady(float x0, float y0, float x1, float y1, float x2, float y2, float c0
return top / bottom;
}
void triangle(uint32_t *dest, int pitch, const TriVertex &v1, const TriVertex &v2, const TriVertex &v3)
void triangle(uint32_t *dest, int pitch, const TriVertex &v1, const TriVertex &v2, const TriVertex &v3, int clipleft, int clipright, const short *cliptop, const short *clipbottom)
{
// 28.4 fixed-point coordinates
const int Y1 = (int)round(16.0f * v1.y);
@ -1311,10 +1311,17 @@ void triangle(uint32_t *dest, int pitch, const TriVertex &v1, const TriVertex &v
const int FDY31 = DY31 << 4;
// Bounding rectangle
int minx = MAX((MIN(MIN(X1, X2), X3) + 0xF) >> 4, 0);
int maxx = MIN((MAX(MAX(X1, X2), X3) + 0xF) >> 4, viewwidth);
int miny = MAX((MIN(MIN(Y1, Y2), Y3) + 0xF) >> 4, 0);
int maxy = MIN((MAX(MAX(Y1, Y2), Y3) + 0xF) >> 4, viewheight);
int clipymin = cliptop[clipleft];
int clipymax = clipbottom[clipleft];
for (int i = clipleft + 1; i <= clipright; i++)
{
clipymin = MIN(clipymin, (int)cliptop[i]);
clipymax = MAX(clipymax, (int)clipbottom[i]);
}
int minx = MAX((MIN(MIN(X1, X2), X3) + 0xF) >> 4, clipleft);
int maxx = MIN((MAX(MAX(X1, X2), X3) + 0xF) >> 4, clipright);
int miny = MAX((MIN(MIN(Y1, Y2), Y3) + 0xF) >> 4, clipymin);
int maxy = MIN((MAX(MAX(Y1, Y2), Y3) + 0xF) >> 4, clipymax);
if (minx >= maxx || miny >= maxy)
return;
@ -1382,6 +1389,13 @@ void triangle(uint32_t *dest, int pitch, const TriVertex &v1, const TriVertex &v
// Skip block when outside an edge
if (a == 0x0 || b == 0x0 || c == 0x0) continue;
// Check if block needs clipping
int clipcount = 0;
for (int ix = 0; ix < q; ix++)
{
clipcount += (cliptop[x + ix] > y) || (clipbottom[x + ix] < y + q - 1);
}
// Calculate varying variables for affine block
float offx0 = (x - minx) + 0.5f;
float offy0 = (y - miny) + 0.5f;
@ -1406,7 +1420,7 @@ void triangle(uint32_t *dest, int pitch, const TriVertex &v1, const TriVertex &v
uint32_t *buffer = dest;
// Accept whole block when totally covered
if (a == 0xF && b == 0xF && c == 0xF)
if (a == 0xF && b == 0xF && c == 0xF && clipcount == 0)
{
for (int iy = 0; iy < q; iy++)
{
@ -1453,7 +1467,9 @@ void triangle(uint32_t *dest, int pitch, const TriVertex &v1, const TriVertex &v
for (int ix = x; ix < x + q; ix++)
{
if (CX1 > 0 && CX2 > 0 && CX3 > 0)
bool visible = (cliptop[ix] <= y + iy) && (clipbottom[ix] >= y + iy);
if (CX1 > 0 && CX2 > 0 && CX3 > 0 && visible)
{
uint32_t red = (uint32_t)clamp(varying[0] * 255.0f + 0.5f, 0.0f, 255.0f);
uint32_t green = (uint32_t)clamp(varying[1] * 255.0f + 0.5f, 0.0f, 255.0f);
@ -1544,6 +1560,16 @@ void clipedge(const TriVertex &v1, const TriVertex &v2, TriVertex *clippedvert,
void R_DrawTriangle()
{
int clipleft = 0;
int clipright = viewwidth - 1;
short cliptop[MAXWIDTH];
short clipbottom[MAXWIDTH];
for (int i = clipleft; i < clipright; i++)
{
cliptop[i] = (i - clipleft) / 4;
clipbottom[i] = viewheight - 1 - (i - clipleft) / 4;
}
TriVertex cube[6 * 6] =
{
{-1.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f },
@ -1615,8 +1641,9 @@ void R_DrawTriangle()
static float angle = 0.0f;
angle = fmod(angle + 0.5f, 360.0f);
VSMatrix objectToWorld(0);
objectToWorld.translate((float)ViewPos.X, (float)ViewPos.Y + 5.0f, (float)ViewPos.Z);
objectToWorld.translate((float)ViewPos.X, (float)ViewPos.Y + 50.0f, (float)ViewPos.Z);
objectToWorld.rotate(angle, 0.57735f, 0.57735f, 0.57735f);
objectToWorld.scale(10.0f, 10.0f, 10.0f);
TriVertex *vinput = cube;
for (int i = 0; i < 6 * 6 / 3; i++)
@ -1679,7 +1706,7 @@ void R_DrawTriangle()
for (int i = numclipvert; i > 1; i--)
{
triangle((uint32_t*)dc_destorg, dc_pitch, clippedvert[numclipvert - 1], clippedvert[i - 1], clippedvert[i - 2]);
triangle((uint32_t*)dc_destorg, dc_pitch, clippedvert[numclipvert - 1], clippedvert[i - 1], clippedvert[i - 2], clipleft, clipright, cliptop, clipbottom);
}
}
}