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EVALCOLR.C
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1992-01-02
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531 lines
/*****************************************************************************
* Routines to evaluate vertices colors for all polygons in data. It is *
* assumed the parser has updated plane equations for all polygons at this *
* stage (if from reading it in, or by regenerating it), and they were mapped *
* correctly using the global transformation applied to them. *
* The vertices are updated for both Flat or Gouraud shading, and color is *
* evaluated for them, as a color index into the color table. Because of the *
* way the table is constructed and because two vertices in same polygon can *
* have two levels of same color, it is o.k. to interplated the color *
* indices (We assume no specular affects)! *
* As side affect, we use this pass to hash the polygon into global hash *
* table PolyHasTable, sorted by their Ymin values. *
* *
* Written by: Gershon Elber Ver 2.0, Mar. 1990 *
*****************************************************************************/
#ifdef __MSDOS__
#include <stdlib.h>
#endif /* __MSDOS__ */
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include "program.h"
#include "iritprsr.h"
#define MIN_VERTEX_HASH_SIZE 1000 /* Minimum number of entries in table. */
typedef struct VertexHashStruct { /* Used to hash an object vertices. */
int Entry;
RealType Normal[3];
IPVertexStruct *PVertex;
} VertexHashStruct;
static RealType MinNormalDotProd; /* Min. normal dot prod to accept as same. */
static int VertexHashSize = 0; /* Size of vertex hash table size allocated. */
static int PolyCount = 0; /* Number of polygons processed in this module: */
static void PrepareAllObjects(IPObjectStruct *PObject);
static void PrepareOneObject(IPObjectStruct *PObject);
static void AverageVrtxNormals(IPObjectStruct *PObject);
static void InsertVerticesToHashTable(VertexHashStruct *VerticesHashTable,
IPObjectStruct *PObject);
static void UpdateVerticesFromHashTable(VertexHashStruct *VerticesHashTable,
IPObjectStruct *PObject);
static int SameVertexAndNormals(IPVertexStruct *PVertex1, RealType *Normal1,
VertexHashStruct *PHVertex2);
static RealType EvalNormalsAngle(IPVertexStruct *PVertex1, RealType *Normal1,
VertexHashStruct *PHVertex2);
static int EvalVertexKey(IPVertexStruct *PVertex);
static void EvalOnePolygon(IPPolygonStruct *PPolygon, int ColorIndex);
static int CosineShading(RealType *Normal, int ColorIndex);
/*****************************************************************************
* Routine to evaluate the vertices colors for both Flat/Gouraud shading, as *
* indices for the color table. *
*****************************************************************************/
void EvalVrtxColors(IPObjectStruct *PObjects)
{
int i;
long
SaveTime = time(NULL);
PolyHashTable = (IPPolygonStruct **)
MyMalloc(sizeof(IPPolygonStruct *) * GlblShadeInfo.ScrnYSize *
GlblShadeInfo.SubSamplePixel);
for (i = 0;
i < GlblShadeInfo.ScrnYSize * GlblShadeInfo.SubSamplePixel;
i++)
PolyHashTable[i] = NULL;
fprintf(stderr, "\nPass 3, Polys [%4d] = ", GlblNumOfPolys);
PrepareAllObjects(PObjects);
fprintf(stderr, ", %ld seconds.", time(NULL) - SaveTime);
}
/*****************************************************************************
* Scan all objects. *
*****************************************************************************/
static void PrepareAllObjects(IPObjectStruct *PObjects)
{
while (PObjects) {
PrepareOneObject(PObjects);
PObjects = PObjects -> Pnext;
}
}
/*****************************************************************************
* Routine to prepare one object Object. *
*****************************************************************************/
static void PrepareOneObject(IPObjectStruct *PObject)
{
static int
WasPolyline = FALSE;
int Level,
ColorIndex = PObject -> Color;
IPPolygonStruct *Ptemp,
*PList = PObject -> U.PPolygon;
if (GlblShadeInfo.Gouraud) {
/* Need to average all vertices normals from adjacent polygons, */
/* so we can interpolate them, and select color for them directly. */
AverageVrtxNormals(PObject);
}
while (PList) {
Ptemp = PList -> Pnext;
EvalOnePolygon(PList, ColorIndex);
/* And add polygon into polygon hash table sorted by Ymin: */
switch (PList -> Type) {
case IP_POLYGON:
/* If BackFacing is TRUE, and this polygon has plane */
/* suggesting it is back facing - dont insert to hash table. */
if (!(GlblShadeInfo.BackFacing && PList -> Plane[2] > 0.0)) {
Level = PList -> Ymin;
Level = BOUND(Level, 0, GlblShadeInfo.ScrnYSize *
GlblShadeInfo.SubSamplePixel); /* Be 100% safe. */
if (Level < GlblShadeInfo.ScrnYSize *
GlblShadeInfo.SubSamplePixel) {
/* Concat to hash table at level Level: */
PList -> Pnext = PolyHashTable[Level];
PolyHashTable[Level] = PList;
}
}
else {
if (!GlblShadeInfo.Gouraud) PolyCount--;/* One less poly.*/
}
break;
case IP_POLYLINE:
if (!WasPolyline) {
WasPolyline = TRUE;
if (GlblMore)
fprintf(stderr,
"\nPolylines are not supported, ignored.\n");
}
break;
}
PList = Ptemp;
}
}
/*****************************************************************************
* Routine to update average normals of adjacent polygons at common vertices *
* so gouraud shading can be applied. Does 2 passes on all object vertices: *
* 1. Combine (and average) common vertices - vertices with normal no differ *
* more than GlblShadeInfo.NrmlAvgDegree degrees. *
* 2. For each vertex find its closest averaged normal as evaluated at 1, and *
* calculate color for it. *
*****************************************************************************/
static void AverageVrtxNormals(IPObjectStruct *PObject)
{
int i;
VertexHashStruct *VerticesHashTable;
/* Prepare maximum degree allowed to merge two normals in cosine form: */
MinNormalDotProd = cos(GlblShadeInfo.NrmlAvgDegree * M_PI / 180.0);
/* Allocate hash table twice as big as number of possible entries to */
/* reduce the average hit ratio, with minimum of MIN_VERTEX_HASH_SIZE. */
VertexHashSize = MAX(GlblNumOfVerts * 2, MIN_VERTEX_HASH_SIZE);
VerticesHashTable = (VertexHashStruct *)
MyMalloc(VertexHashSize * sizeof(VertexHashStruct));
for (i = 0; i < VertexHashSize; i++) VerticesHashTable[i].Entry = 0;
InsertVerticesToHashTable(VerticesHashTable, PObject);
UpdateVerticesFromHashTable(VerticesHashTable, PObject);
free((char *) VerticesHashTable);
}
/*****************************************************************************
* Routine to insert all vertices in object into the hash table. Each vertex *
* is entered at place (key) as select via EvalVertexKey routine. If no place *
* the next ones are scaned until free (NULL) is found (no double key fansy *
* hashing techniques...). Note however that while scanning the non NULL *
* entries the vertex position is compared for equality, and its normal for *
* equality upto AvgNormalDegree, and if both hold, the two are merged into *
* one vertex in that position but with averaged normal. *
*****************************************************************************/
static void InsertVerticesToHashTable(VertexHashStruct *VerticesHashTable,
IPObjectStruct *PObject)
{
int i, Key;
RealType EntryRatio, *Normal, *OldNormal;
IPPolygonStruct *PPolygon;
IPVertexStruct *PVertex;
for (PPolygon = PObject -> U.PPolygon;
PPolygon != NULL;
PPolygon = PPolygon -> Pnext) {
Normal = PPolygon -> Plane;
/* If BackFacing is TRUE, and this polygon has plane */
/* suggesting it is back facing - dont count it. */
if (!(GlblShadeInfo.BackFacing && PPolygon -> Plane[2] < 0.0))
PolyCount++;
fprintf(stderr, "\b\b\b\b\b%5d", PolyCount);
for (PVertex = PPolygon -> PVertex;
PVertex != NULL;
PVertex = PVertex -> Pnext) {
Key = EvalVertexKey(PVertex);
while (VerticesHashTable[Key].Entry != 0) {
/* Test if should be combined with old vertex: */
if (SameVertexAndNormals(PVertex, Normal,
&VerticesHashTable[Key])) {
/* Megre the normals: */
EntryRatio = 1.0 / ++VerticesHashTable[Key].Entry;
OldNormal = VerticesHashTable[Key].Normal;
for (i = 0; i < 3; i++) OldNormal[i] =
OldNormal[i] * (1.0 - EntryRatio) +
Normal[i] * EntryRatio;
break;
}
Key = ++Key % VertexHashSize;
}
if (VerticesHashTable[Key].Entry == 0) {
/* Could not merge the vertex with old one - do it now: */
VerticesHashTable[Key].PVertex = PVertex;
GEN_COPY(VerticesHashTable[Key].Normal, Normal,
3 * sizeof(RealType));
++VerticesHashTable[Key].Entry;
}
}
}
}
/*****************************************************************************
* Routine to scan all vertices in object and update their normals to the *
* close one at that point as found in the hash table. *
*****************************************************************************/
static void UpdateVerticesFromHashTable(VertexHashStruct *VerticesHashTable,
IPObjectStruct *PObject)
{
static int
Flip = FALSE;
int Key;
RealType *Normal, MaxCosAngle, CosAngle;
IPPolygonStruct *PPolygon;
IPVertexStruct *PVertex;
VertexHashStruct *PHVertex;
for (PPolygon = PObject -> U.PPolygon;
PPolygon != NULL;
PPolygon = PPolygon -> Pnext) {
Normal = PPolygon -> Plane;
if (Flip) {
Flip = FALSE;
fprintf(stderr, "a\b");
}
else {
Flip = TRUE;
fprintf(stderr, "A\b");
}
PVertex = PPolygon -> PVertex;
for (PVertex = PPolygon -> PVertex;
PVertex != NULL;
PVertex = PVertex -> Pnext) {
PHVertex = NULL;
MaxCosAngle = -INFINITY;
Key = EvalVertexKey(PVertex);
while (VerticesHashTable[Key].Entry != 0) {
/* Search for the closest Normal at this vertex point: */
if ((CosAngle = (EvalNormalsAngle(PVertex, Normal,
&VerticesHashTable[Key]))) > MaxCosAngle) {
PHVertex = &VerticesHashTable[Key];
MaxCosAngle = CosAngle;
}
Key = ++Key % VertexHashSize;
}
if (IP_HAS_VRTX_NORMAL(PVertex)) {
/* Use defined normal for this vertex, if has one. */
PVertex -> Color = CosineShading(PVertex -> Normal,
PObject -> Color);
}
else if (PHVertex) {
/* Should always be non NULL but who knows... */
PVertex -> Color = CosineShading(PHVertex -> Normal,
PObject -> Color);
}
else {
PVertex -> Color = CosineShading(PPolygon -> Plane,
PObject -> Color);
}
}
}
}
/*****************************************************************************
* Routine to compare two vertices to be exactly equal in their position and *
* to have same normal up to GlblShadeInfo.NrmlAvgDegree. *
*****************************************************************************/
static int SameVertexAndNormals(IPVertexStruct *PVertex1, RealType *Normal1,
VertexHashStruct *PHVertex2)
{
RealType *Normal2,
*Coord1 = PVertex1 -> Coord,
*Coord2 = PHVertex2 -> PVertex -> Coord;
if (!APX_EQ(Coord1[0], Coord2[0]) ||
!APX_EQ(Coord1[1], Coord2[1]) ||
!APX_EQ(Coord1[2], Coord2[2])) return FALSE;
Normal2 = PHVertex2 -> Normal;
return (Normal1[0] * Normal2[0] +
Normal1[1] * Normal2[1] +
Normal1[2] * Normal2[2] > MinNormalDotProd);
}
/*****************************************************************************
* Routine to evaluate the angle between the given two vertices if they are *
* the same, and return the angle cosine value. (-INFINITY is returned if *
* not same point...). *
*****************************************************************************/
static RealType EvalNormalsAngle(IPVertexStruct *PVertex1, RealType *Normal1,
VertexHashStruct *PHVertex2)
{
RealType *Normal2,
*Coord1 = PVertex1 -> Coord,
*Coord2 = PHVertex2 -> PVertex -> Coord;
if (!APX_EQ(Coord1[0], Coord2[0]) ||
!APX_EQ(Coord1[1], Coord2[1]) ||
!APX_EQ(Coord1[2], Coord2[2])) return -INFINITY;
Normal2 = PHVertex2 -> Normal;
return Normal1[0] * Normal2[0] +
Normal1[1] * Normal2[1] +
Normal1[2] * Normal2[2];
}
/*****************************************************************************
* Routine to evaluate integer key in the range 0 .. VertexHashSize - 1 *
* for the given vertex PVertex. *
*****************************************************************************/
static int EvalVertexKey(IPVertexStruct *PVertex)
{
int Key;
RealType
*Coord = PVertex -> Coord;
Key = ((int) (((long) (Coord[0] * 239 + Coord[1] * 677 + Coord[2] * 109)) %
VertexHashSize));
return Key;
}
/*****************************************************************************
* Routine to update the vertices colors, which are indices tp the ColorMap *
* as save in global GlblShadeInfo structure. Given Object color (as index *
* into table), the exact level is evaluationed using each polygon normal. *
*****************************************************************************/
static void EvalOnePolygon(IPPolygonStruct *PPolygon, int ColorIndex)
{
int Color;
IPVertexStruct
*V = PPolygon -> PVertex;
if (GlblShadeInfo.Gouraud) {
/* Vertices were already updated by the Object averaging of normals */
/* routine (see AverageVrtxNormals routine). */
}
else {
fprintf(stderr, "\b\b\b\b\b%5d", ++PolyCount);
/* This is much easier - set all vertices color to same Color. */
Color = CosineShading(PPolygon -> Plane, ColorIndex);
for (; V != NULL; V = V -> Pnext) V -> Color = Color;
}
}
/*****************************************************************************
* Routine to evaluate cosine shading given a normal vector. Uses the global *
* shading structure GlblShadeInfo to evaluate it. Returns a color from the *
* color map defined for the current scene. *
* It is assumed the given normal is normalized to size 1.0, and that the *
* intensity levels of the Object Color are saved in indices PObject -> Color *
* to PObject -> Color + GlblShadeInfo.LevelsPerColor - 1. These colors are *
* interpolated to begin from the ambient level, so we dont have to consider *
* ambient light here - just the cosine factor. *
*****************************************************************************/
static int CosineShading(RealType *Normal, int ColorIndex)
{
int NewColorIndex;
RealType Intensity;
if (GlblShadeInfo.TwoSources) {
/* Take the absolute value of the dot product as intensity: */
Intensity = Normal[0] * GlblShadeInfo.LightSource[0] +
Normal[1] * GlblShadeInfo.LightSource[1] +
Normal[2] * GlblShadeInfo.LightSource[2];
Intensity = ABS(Intensity);
}
else {
/* Dot product of two normals is in [-1..1] range. Make it [0..1]: */
Intensity = (Normal[0] * GlblShadeInfo.LightSource[0] +
Normal[1] * GlblShadeInfo.LightSource[1] +
Normal[2] * GlblShadeInfo.LightSource[2] + 1.0) * 0.5;
}
NewColorIndex = ColorIndex +
((int) ((GlblShadeInfo.LevelsPerColor - 1) * (1.0 - Intensity)));
/* This should never happen, but if it does, the error is so fatal */
/* (generate different color tone instead...) we double check this one. */
return BOUND(NewColorIndex, ColorIndex,
ColorIndex + GlblShadeInfo.LevelsPerColor - 1);
}
/*****************************************************************************
* Routine to update plane equation of the given polygon: *
* It is assumed that at list 3 points in polygon do exists, and pick the *
* tuple that has biggest length for maximum accuracy. *
* Note the polygon must be convex. *
* Returns FALSE if failed to evaluate the PLANE equation. *
*****************************************************************************/
int UpdateEqnPolygon(IPPolygonStruct *PPolygon, int SetFlipDir)
{
int i, FlipPlaneDir;
RealType Len, V1[3], V2[3], *Coord, *CoordNext, *CoordNextNext, Plane[3],
MaxPlane[3],
MaxLen = 0.0;
IPVertexStruct
*VList = PPolygon -> PVertex;
/* Search for 3 consequtive non-colinear point from polygon: */
for (; VList -> Pnext -> Pnext != NULL; VList = VList -> Pnext) {
Coord = VList -> Coord;
CoordNext = VList -> Pnext -> Coord;
CoordNextNext = VList -> Pnext -> Pnext -> Coord;
if (!PT_EQ(Coord, CoordNext) &&
!PT_EQ(CoordNext, CoordNextNext)) {
for (i = 0; i < 3; i++) {/* Prepare two vectors on polygon plane.*/
V1[i] = Coord[i] - CoordNext[i];
V2[i] = CoordNext[i] - CoordNextNext[i];
}
/* Find plane normal by a cross product of two vectors on plane: */
Plane[0] = V1[1] * V2[2] - V1[2] * V2[1];
Plane[1] = V1[2] * V2[0] - V1[0] * V2[2];
Plane[2] = V1[0] * V2[1] - V1[1] * V2[0];
/* Find vector Len. - we are looking for the biggest: */
Len = sqrt(SQR(Plane[0]) + SQR(Plane[1]) + SQR(Plane[2]));
if (Len > MaxLen) {
for (i = 0; i < 3; i++) MaxPlane[i] = Plane[i];
MaxLen = Len;
}
}
}
if (ABS(MaxLen) < SQR(EPSILON)) { /* Fail to find 3 non-colinear points. */
if (GlblMore) {
fprintf(stderr,
"\nError: Invalid polygon (%d) found in file (zero edge length/colinear vertices):\n",
PolyCount);
PrintPolyContent(PPolygon);
}
PPolygon -> Plane[0] = PPolygon -> Plane[1] = 0.0; /* Pick Z = 1.0. */
PPolygon -> Plane[2] = PPolygon -> Plane[2] = 1.0;
return FALSE;
}
if (SetFlipDir) {
FlipPlaneDir =
PPolygon -> Plane[0] * MaxPlane[0] +
PPolygon -> Plane[1] * MaxPlane[1] +
PPolygon -> Plane[2] * MaxPlane[2] < 0.0;
}
else
FlipPlaneDir = 1;
for (i = 0; i < 3; i++)
PPolygon -> Plane[i] = (FlipPlaneDir ? -1 : 1)
* MaxPlane[i] / MaxLen;
PPolygon -> Plane[3] =
(- Coord[0] * PPolygon -> Plane[0]
- Coord[1] * PPolygon -> Plane[1]
- Coord[2] * PPolygon -> Plane[2]);
return TRUE;
}
/*****************************************************************************
* Routine to evaluate the cross product of 3 points projected to Z = 0 plane *
* and return the sign of the result (Only Z component). *
*****************************************************************************/
int CrossProd(RealType Pt1[3], RealType Pt2[3], RealType Pt3[3])
{
RealType Zout;
/* U = Pt2 - Pt1, V = Pt3 - Pt2, Zoutput = Ux * Vy - Uy * Vx. */
Zout = (Pt2[0] - Pt1[0]) /* Ux */ * (Pt3[1] - Pt2[1]) /* Vy */ -
(Pt2[1] - Pt1[1]) /* Uy */ * (Pt3[0] - Pt2[0]) /* Vx */;
if (APX_EQ(Zout, 0.0)) return 0;
if (Zout < 0.0)
return -1;
else
return 1;
}
/*****************************************************************************
* Routine to print the content of a given edge: *
*****************************************************************************/
void PrintPolyContent(IPPolygonStruct *PPoly)
{
IPVertexStruct
*VList = PPoly -> PVertex;
for (; VList != NULL; VList = VList -> Pnext) {
fprintf(stderr, " %12f %12f %12f\n",
VList -> Coord[0],
VList -> Coord[1],
VList -> Coord[2]);
}
}