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Snap triangle x,y vertices to 1/16 subpixel positions.

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Disabled tiny triangle threshold test.
This commit is contained in:
Brian Paul 2001-06-12 14:18:58 +00:00
parent 57b46ee6ea
commit a2162e4228
1 changed files with 55 additions and 34 deletions
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89
src/mesa/swrast/s_tritemp.h
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@ -1,4 +1,4 @@
/* $Id: s_tritemp.h,v 1.17 2001/05/16 20:27:12 brianp Exp $ */
/* $Id: s_tritemp.h,v 1.18 2001/06/12 14:18:58 brianp Exp $ */
/*
* Mesa 3-D graphics library
@ -95,6 +95,8 @@
const SWvertex *vMin, *vMid, *vMax; /* Y(vMin)<=Y(vMid)<=Y(vMax) */
float bf = SWRAST_CONTEXT(ctx)->_backface_sign;
GLboolean tiny;
const GLint snapMask = ~((FIXED_ONE / 16) - 1); /* for x/y coord snapping */
GLfixed vMin_fx, vMin_fy, vMid_fx, vMid_fy, vMax_fx, vMax_fy;
struct triangle_span span;
@ -102,34 +104,56 @@
(void) fixedToDepthShift;
#endif
/* find the order of the 3 vertices along the Y axis */
/* Compute fixed point x,y coords w/ half-pixel offsets and snapping.
* And find the order of the 3 vertices along the Y axis.
*/
{
GLfloat y0 = v0->win[1];
GLfloat y1 = v1->win[1];
GLfloat y2 = v2->win[1];
const GLfixed fy0 = FloatToFixed(v0->win[1] + 0.5F) & snapMask;
const GLfixed fy1 = FloatToFixed(v1->win[1] + 0.5F) & snapMask;
const GLfixed fy2 = FloatToFixed(v2->win[1] + 0.5F) & snapMask;
if (y0<=y1) {
if (y1<=y2) {
vMin = v0; vMid = v1; vMax = v2; /* y0<=y1<=y2 */
if (fy0 <= fy1) {
if (fy1 <= fy2) {
/* y0 <= y1 <= y2 */
vMin = v0; vMid = v1; vMax = v2;
vMin_fy = fy0; vMid_fy = fy1; vMax_fy = fy2;
}
else if (y2<=y0) {
vMin = v2; vMid = v0; vMax = v1; /* y2<=y0<=y1 */
else if (fy2 <= fy0) {
/* y2 <= y0 <= y1 */
vMin = v2; vMid = v0; vMax = v1;
vMin_fy = fy2; vMid_fy = fy0; vMax_fy = fy1;
}
else {
vMin = v0; vMid = v2; vMax = v1; bf = -bf; /* y0<=y2<=y1 */
/* y0 <= y2 <= y1 */
vMin = v0; vMid = v2; vMax = v1;
vMin_fy = fy0; vMid_fy = fy2; vMax_fy = fy1;
bf = -bf;
}
}
else {
if (y0<=y2) {
vMin = v1; vMid = v0; vMax = v2; bf = -bf; /* y1<=y0<=y2 */
if (fy0 <= fy2) {
/* y1 <= y0 <= y2 */
vMin = v1; vMid = v0; vMax = v2;
vMin_fy = fy1; vMid_fy = fy0; vMax_fy = fy2;
bf = -bf;
}
else if (y2<=y1) {
vMin = v2; vMid = v1; vMax = v0; bf = -bf; /* y2<=y1<=y0 */
else if (fy2 <= fy1) {
/* y2 <= y1 <= y0 */
vMin = v2; vMid = v1; vMax = v0;
vMin_fy = fy2; vMid_fy = fy1; vMax_fy = fy0;
bf = -bf;
}
else {
vMin = v1; vMid = v2; vMax = v0; /* y1<=y2<=y0 */
/* y1 <= y2 <= y0 */
vMin = v1; vMid = v2; vMax = v0;
vMin_fy = fy1; vMid_fy = fy2; vMax_fy = fy0;
}
}
/* fixed point X coords */
vMin_fx = FloatToFixed(vMin->win[0] + 0.5F) & snapMask;
vMid_fx = FloatToFixed(vMid->win[0] + 0.5F) & snapMask;
vMax_fx = FloatToFixed(vMax->win[0] + 0.5F) & snapMask;
}
/* vertex/edge relationship */
@ -137,15 +161,15 @@
eTop.v0 = vMid; eTop.v1 = vMax;
eBot.v0 = vMin; eBot.v1 = vMid;
/* compute deltas for each edge: vertex[v1] - vertex[v0] */
eMaj.dx = vMax->win[0] - vMin->win[0];
eMaj.dy = vMax->win[1] - vMin->win[1];
eTop.dx = vMax->win[0] - vMid->win[0];
eTop.dy = vMax->win[1] - vMid->win[1];
eBot.dx = vMid->win[0] - vMin->win[0];
eBot.dy = vMid->win[1] - vMin->win[1];
/* compute deltas for each edge: vertex[upper] - vertex[lower] */
eMaj.dx = FixedToFloat(vMax_fx - vMin_fx);
eMaj.dy = FixedToFloat(vMax_fy - vMin_fy);
eTop.dx = FixedToFloat(vMax_fx - vMid_fx);
eTop.dy = FixedToFloat(vMax_fy - vMid_fy);
eBot.dx = FixedToFloat(vMid_fx - vMin_fx);
eBot.dy = FixedToFloat(vMid_fy - vMin_fy);
/* compute oneOverArea */
/* compute area, oneOverArea and perform backface culling */
{
const GLfloat area = eMaj.dx * eBot.dy - eBot.dx * eMaj.dy;
@ -156,12 +180,16 @@
if (area == 0.0F)
return;
/* This may not be needed anymore. Let's see if anyone reports a problem. */
#if 0
/* check for very tiny triangle */
if (area * area < (0.05F * 0.05F)) { /* square to ensure positive value */
oneOverArea = 1.0F / 0.05F; /* a close-enough value */
if (area * area < (0.001F * 0.001F)) { /* square to ensure positive value */
oneOverArea = 1.0F / 0.001F; /* a close-enough value */
tiny = GL_TRUE;
}
else {
else
#endif
{
oneOverArea = 1.0F / area;
tiny = GL_FALSE;
}
@ -173,13 +201,6 @@
/* Edge setup. For a triangle strip these could be reused... */
{
/* fixed point Y coordinates */
GLfixed vMin_fx = FloatToFixed(vMin->win[0] + 0.5F);
GLfixed vMin_fy = FloatToFixed(vMin->win[1] - 0.5F);
GLfixed vMid_fx = FloatToFixed(vMid->win[0] + 0.5F);
GLfixed vMid_fy = FloatToFixed(vMid->win[1] - 0.5F);
GLfixed vMax_fy = FloatToFixed(vMax->win[1] - 0.5F);
eMaj.fsy = FixedCeil(vMin_fy);
eMaj.lines = FixedToInt(FixedCeil(vMax_fy - eMaj.fsy));
if (eMaj.lines > 0) {