GENSTRIP.C
/******************************Module*Header*******************************\
* Module Name: genstrip.c
*
* The Ribbon and 2 Ribbon styles of the 3D Flying Objects screen saver.
*
* Animation of 1 or 2 quad strips floating about.
*
* Copyright (c) 1994 Microsoft Corporation
*
\**************************************************************************/
#include <windows.h>
#include <GL\gl.h>
#include <string.h>
#include <math.h>
#include "ss3dfo.h"
#include "mesh.h"
static MESH stripMesh;
static int iPrec = 40;
void genStrip()
{
static int counter = 0;
int i;
int facecount;
// Use Hermite basis, pg 488, FVD
static float M[4][4] = {{2.0f, -2.0f, 1.0f, 1.0f},
{-3.0f, 3.0f, -2.0f, -1.0f},
{0.0f, 0.0f, 1.0f, 0.0f},
{1.0f, 0.0f, 0.0f, 0.0f}};
float xx[4], yy[4], zz[4];
float cx[4], cy[4], cz[4];
float d = 1.0f / (float) iPrec;
float t = 0.0f;
float t2, t3;
POINT3D p1 = {-0.5f, 0.0f, 0.0f};
POINT3D p2 = {0.5f, 0.0f, 0.0f};
POINT3D v1 = {1.5f, 1.5f, 0.0f};
POINT3D v2 = {0.0f, 3.0f, 0.0f};
POINT3D norm;
float sinVal;
float angle;
float angleStep = (float) (PI / iPrec);
static float rotA = 0.0f;
static float rotB = (float) (PI / 2.0);
static float sideSin = 0.0f;
float rotStepA = (float) (PI / (2.0 * iPrec));
float rotStepB = (float) (PI / (4.0 * iPrec));
MESH *mesh = &stripMesh;
#define NORMS(x, y) stripMesh.norms[((x) * iPrec) + y]
#define GRID(x, y) stripMesh.pts[((x) * iPrec) + y]
v1.x = (float) (4.0 * cos(rotA));
v1.y = (float) (4.0 * sin(rotA));
p2.x = (float) (0.5 * sin(rotB));
// p2.y = (float) (0.5 * sin(rotB));
rotA += rotStepA;
rotB += rotStepB;
counter++;
if (counter >= (2 * iPrec)) {
rotStepA = -rotStepA;
counter = 0;
}
angle = sideSin;
sideSin += (float) (PI / 80.0);
xx[0] = p1.x;
xx[1] = p2.x;
xx[2] = v1.x;
xx[3] = v2.x;
yy[0] = p1.y;
yy[1] = p2.y;
yy[2] = v1.y;
yy[3] = v2.y;
zz[0] = p1.z;
zz[1] = p2.z;
zz[2] = v1.z;
zz[3] = v2.z;
for (i = 0; i < 4; i++) {
cx[i] = xx[0] * M[i][0] + xx[1] * M[i][1] +
xx[2] * M[i][2] + xx[3] * M[i][3];
cy[i] = yy[0] * M[i][0] + yy[1] * M[i][1] +
yy[2] * M[i][2] + yy[3] * M[i][3];
cz[i] = zz[0] * M[i][0] + zz[1] * M[i][1] +
zz[2] * M[i][2] + zz[3] * M[i][3];
}
for (i = 0; i < iPrec; i++) {
float x, y;
t += d;
t2 = t * t;
t3 = t2 * t;
x = cx[0] * t3 + cx[1] * t2 + cx[2] * t + cx[3];
y = cy[0] * t3 + cy[1] * t2 + cy[2] * t + cy[3];
sinVal = (float) (sin(angle) / 5.0);
if (sinVal < 0.0)
sinVal = -sinVal;
angle += angleStep;
GRID(0, i).x = x;
GRID(0, i).z = y;
GRID(0, i).y = 0.25f; // extrusion // + sinVal;
GRID(1, i).x = x;
GRID(1, i).z = y;
GRID(1, i).y = -0.25f; // - sinVal;
}
stripMesh.numFaces = 0;
for (i = 0; i < 2 * iPrec; i++)
mesh->norms[i] = ss_ptZero;
for (facecount = 0, i = 0; i < (iPrec - 1); i++) {
ss_calcNorm(&norm, &GRID(0, i + 1), &GRID(0, i), &GRID(1, i));
stripMesh.faces[facecount].material = 0;
stripMesh.faces[facecount].norm = norm;
NORMS(0, i).x += norm.x;
NORMS(0, i).y += norm.y;
NORMS(0, i).z += norm.z;
NORMS(1, i).x += norm.x;
NORMS(1, i).y += norm.y;
NORMS(1, i).z += norm.z;
if (i != (iPrec - 1)) {
NORMS(0, i+1).x += norm.x;
NORMS(0, i+1).y += norm.y;
NORMS(0, i+1).z += norm.z;
NORMS(1, i+1).x += norm.x;
NORMS(1, i+1).y += norm.y;
NORMS(1, i+1).z += norm.z;
}
stripMesh.faces[facecount].p[0] = i;
stripMesh.faces[facecount].p[1] = iPrec + i;
stripMesh.faces[facecount].p[2] = i + 1;
stripMesh.faces[facecount].p[3] = iPrec + i + 1;
stripMesh.numFaces++;
facecount++;
}
stripMesh.numPoints = 2 * iPrec;
ss_normalizeNorms(stripMesh.norms, stripMesh.numPoints);
}
void initStripScene()
{
iPrec = (int)(fTesselFact * 40.5);
if (iPrec < 4)
iPrec = 4;
newMesh(&stripMesh, iPrec, 2 * iPrec);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.1, 1.1, -1.1, 1.1, 0.0, 3.0);
glTranslatef(0.0f, 0.0f, -1.5f);
glRotatef(50.0f, 1.0f, 0.0f, 0.0f);
glRotatef(50.0f, 0.0f, 1.0f, 0.0f);
glRotatef(12.0f, 0.0f, 0.0f, 1.0f);
glMatrixMode(GL_MODELVIEW);
}
void delStripScene()
{
delMesh(&stripMesh);
}
void updateStripScene(int flags)
{
static double mxrot = 0.0;
static double myrot = 0.0;
static double mzrot = 0.0;
static double mxrotInc = 0.0;
static double myrotInc = 0.1;
static double mzrotInc = 0.0;
static int h = 0;
RGBA color;
if( gbBounce ) {
// floating window bounced off an edge
if (mxrotInc) {
mxrotInc = 0.0;
myrotInc = 0.1;
} else if (myrotInc) {
myrotInc = 0.0;
mzrotInc = 0.1;
} else if (mzrotInc) {
mzrotInc = 0.0;
mxrotInc = 0.1;
}
gbBounce = FALSE;
}
glLoadIdentity();
glRotatef((GLfloat) (mxrot * (180.0 / PI)), 1.0f, 0.0f, 0.0f);
glRotatef((GLfloat) (myrot * (180.0 / PI)), 0.0f, 1.0f, 0.0f);
glRotatef((GLfloat) (mzrot * (180.0 / PI)), 0.0f, 0.0f, 1.0f);
genStrip();
if (bColorCycle) {
ss_HsvToRgb((float)h, 1.0f, 1.0f, &color );
glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE,
(GLfloat *) &color);
h++;
h %= 360;
} else {
glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE,
(GLfloat *) &Material[1].kd);
}
updateObject(&stripMesh, bSmoothShading);
if (flags & 0x4) {
glLoadIdentity();
glTranslatef(0.05f, 0.0f, 0.0f);
glRotatef((GLfloat) (myrot * (180.0 / PI)), 1.0f, 0.0f, 0.0f);
glRotatef((GLfloat) (mxrot * (180.0 / PI)), 0.0f, 1.0f, 0.0f);
glRotatef((GLfloat) (mzrot * (180.0 / PI)), 0.0f, 0.0f, 1.0f);
if (bColorCycle) {
color.r = 1.0f - color.r;
color.g = 1.0f - color.g;
color.b = 1.0f - color.b;
glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE,
(GLfloat *) &color);
} else {
glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE,
(GLfloat *) &Material[2].kd);
}
updateObject(&stripMesh, bSmoothShading);
}
mxrot += mxrotInc;
myrot += myrotInc;
mzrot += mzrotInc;
}