/* 08_vertex_transform.c - OpenGL-based vertex transform example
using Cg program from Chapter 4 of "The Cg Tutorial" (Addison-Wesley,
ISBN 0321194969). */
/* Requires the OpenGL Utility Toolkit (GLUT) and Cg runtime (version
1.5 or higher). */
#include <stdio.h> /* for printf and NULL */
#include <stdlib.h> /* for exit */
#include <math.h> /* for sqrt, sin, and cos */
#include <assert.h> /* for assert */
#include <GL/glew.h>
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
#ifdef _WIN32
#include <GL/wglew.h>
#else
#ifdef __APPLE__
#include <OpenGL/OpenGL.h>
#else
#include <GL/glxew.h>
#endif
#endif
#include <Cg/cg.h> /* Can't include this? Is Cg Toolkit installed! */
#include <Cg/cgGL.h>
static CGcontext myCgContext;
static CGprofile myCgVertexProfile,
myCgFragmentProfile;
static CGprogram myCgVertexProgram,
myCgFragmentProgram;
static CGparameter myCgVertexParam_modelViewProj,
myCgFragmentParam_c;
static const char *myProgramName = "08_vertex_transform",
*myVertexProgramFileName = "C4E1v_transform.cg",
/* Page 97 */ *myVertexProgramName = "C4E1v_transform";
static float myEyeAngle = 0; /* Angle eye rotates around scene. */
static float myProjectionMatrix[16];
static void checkForCgError(const char *situation)
{
CGerror error;
const char *string = cgGetLastErrorString(&error);
if (error != CG_NO_ERROR) {
printf("%s: %s: %s\n",
myProgramName, situation, string);
if (error == CG_COMPILER_ERROR) {
printf("%s\n", cgGetLastListing(myCgContext));
}
exit(1);
}
}
/* Forward declared GLUT callbacks registered by main. */
static void reshape(int width, int height);
static void display(void);
static void keyboard(unsigned char c, int x, int y);
static void menu(int item);
static void requestSynchronizedSwapBuffers(void);
int main(int argc, char **argv)
{
glutInitWindowSize(400, 400);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
glutInit(&argc, argv);
glutCreateWindow(myProgramName);
glutDisplayFunc(display);
glutKeyboardFunc(keyboard);
glutReshapeFunc(reshape);
/* Initialize OpenGL entry points. */
if (glewInit()!=GLEW_OK || !GLEW_VERSION_1_1) {
fprintf(stderr, "%s: failed to initialize GLEW, OpenGL 1.1 required.\n", myProgramName);
exit(1);
}
requestSynchronizedSwapBuffers();
glClearColor(0.1, 0.1, 0.1, 0); /* Gray background. */
glEnable(GL_DEPTH_TEST); /* Hidden surface removal. */
myCgContext = cgCreateContext();
checkForCgError("creating context");
cgGLSetDebugMode(CG_FALSE);
cgSetParameterSettingMode(myCgContext, CG_DEFERRED_PARAMETER_SETTING);
myCgVertexProfile = cgGLGetLatestProfile(CG_GL_VERTEX);
cgGLSetOptimalOptions(myCgVertexProfile);
checkForCgError("selecting vertex profile");
myCgVertexProgram =
cgCreateProgramFromFile(
myCgContext, /* Cg runtime context */
CG_SOURCE, /* Program in human-readable form */
myVertexProgramFileName, /* Name of file containing program */
myCgVertexProfile, /* Profile: OpenGL ARB vertex program */
myVertexProgramName, /* Entry function name */
NULL); /* No extra compiler options */
checkForCgError("creating vertex program from file");
cgGLLoadProgram(myCgVertexProgram);
checkForCgError("loading vertex program");
myCgVertexParam_modelViewProj =
cgGetNamedParameter(myCgVertexProgram, "modelViewProj");
checkForCgError("could not get modelViewProj parameter");
myCgFragmentProfile = cgGLGetLatestProfile(CG_GL_FRAGMENT);
cgGLSetOptimalOptions(myCgFragmentProfile);
checkForCgError("selecting fragment profile");
/* Specify fragment program with a string. */
myCgFragmentProgram =
cgCreateProgram(
myCgContext, /* Cg runtime context */
CG_SOURCE, /* Program in human-readable form */
"float4 main(uniform float4 c) : COLOR { return c; }",
myCgFragmentProfile, /* Profile: latest fragment profile */
"main", /* Entry function name */
NULL); /* No extra compiler options */
checkForCgError("creating fragment program from string");
cgGLLoadProgram(myCgFragmentProgram);
checkForCgError("loading fragment program");
myCgFragmentParam_c =
cgGetNamedParameter(myCgFragmentProgram, "c");
checkForCgError("could not get c parameter");
glutCreateMenu(menu);
glutAddMenuEntry("[ ] Animate", ' ');
glutAttachMenu(GLUT_RIGHT_BUTTON);
glutMainLoop();
return 0;
}
/* Forward declared routine used by reshape callback. */
static void buildPerspectiveMatrix(double, double,
double, double, float m[16]);
static void reshape(int width, int height)
{
double aspectRatio = (float) width / (float) height;
double fieldOfView = 40.0; /* Degrees */
/* Build projection matrix once. */
buildPerspectiveMatrix(fieldOfView, aspectRatio,
1.0, 20.0, /* Znear and Zfar */
myProjectionMatrix);
glViewport(0, 0, width, height);
}
static const double myPi = 3.14159265358979323846;
static void buildPerspectiveMatrix(double fieldOfView,
double aspectRatio,
double zNear, double zFar,
float m[16])
{
double sine, cotangent, deltaZ;
double radians = fieldOfView / 2.0 * myPi / 180.0;
deltaZ = zFar - zNear;
sine = sin(radians);
/* Should be non-zero to avoid division by zero. */
assert(deltaZ);
assert(sine);
assert(aspectRatio);
cotangent = cos(radians) / sine;
m[0*4+0] = cotangent / aspectRatio;
m[0*4+1] = 0.0;
m[0*4+2] = 0.0;
m[0*4+3] = 0.0;
m[1*4+0] = 0.0;
m[1*4+1] = cotangent;
m[1*4+2] = 0.0;
m[1*4+3] = 0.0;
m[2*4+0] = 0.0;
m[2*4+1] = 0.0;
m[2*4+2] = -(zFar + zNear) / deltaZ;
m[2*4+3] = -2 * zNear * zFar / deltaZ;
m[3*4+0] = 0.0;
m[3*4+1] = 0.0;
m[3*4+2] = -1;
m[3*4+3] = 0;
}
/* Build a row-major (C-style) 4x4 matrix transform based on the
parameters for gluLookAt. */
static void buildLookAtMatrix(double eyex, double eyey, double eyez,
double centerx, double centery, double centerz,
double upx, double upy, double upz,
float m[16])
{
double x[3], y[3], z[3], mag;
/* Difference eye and center vectors to make Z vector. */
z[0] = eyex - centerx;
z[1] = eyey - centery;
z[2] = eyez - centerz;
/* Normalize Z. */
mag = sqrt(z[0]*z[0] + z[1]*z[1] + z[2]*z[2]);
if (mag) {
z[0] /= mag;
z[1] /= mag;
z[2] /= mag;
}
/* Up vector makes Y vector. */
y[0] = upx;
y[1] = upy;
y[2] = upz;
/* X vector = Y cross Z. */
x[0] = y[1]*z[2] - y[2]*z[1];
x[1] = -y[0]*z[2] + y[2]*z[0];
x[2] = y[0]*z[1] - y[1]*z[0];
/* Recompute Y = Z cross X. */
y[0] = z[1]*x[2] - z[2]*x[1];
y[1] = -z[0]*x[2] + z[2]*x[0];
y[2] = z[0]*x[1] - z[1]*x[0];
/* Normalize X. */
mag = sqrt(x[0]*x[0] + x[1]*x[1] + x[2]*x[2]);
if (mag) {
x[0] /= mag;
x[1] /= mag;
x[2] /= mag;
}
/* Normalize Y. */
mag = sqrt(y[0]*y[0] + y[1]*y[1] + y[2]*y[2]);
if (mag) {
y[0] /= mag;
y[1] /= mag;
y[2] /= mag;
}
/* Build resulting view matrix. */
m[0*4+0] = x[0]; m[0*4+1] = x[1];
m[0*4+2] = x[2]; m[0*4+3] = -x[0]*eyex + -x[1]*eyey + -x[2]*eyez;
m[1*4+0] = y[0]; m[1*4+1] = y[1];
m[1*4+2] = y[2]; m[1*4+3] = -y[0]*eyex + -y[1]*eyey + -y[2]*eyez;
m[2*4+0] = z[0]; m[2*4+1] = z[1];
m[2*4+2] = z[2]; m[2*4+3] = -z[0]*eyex + -z[1]*eyey + -z[2]*eyez;
m[3*4+0] = 0.0; m[3*4+1] = 0.0; m[3*4+2] = 0.0; m[3*4+3] = 1.0;
}
static void makeRotateMatrix(float angle,
float ax, float ay, float az,
float m[16])
{
float radians, sine, cosine, ab, bc, ca, tx, ty, tz;
float axis[3];
float mag;
axis[0] = ax;
axis[1] = ay;
axis[2] = az;
mag = sqrt(axis[0]*axis[0] + axis[1]*axis[1] + axis[2]*axis[2]);
if (mag) {
axis[0] /= mag;
axis[1] /= mag;
axis[2] /= mag;
}
radians = angle * myPi / 180.0;
sine = sin(radians);
cosine = cos(radians);
ab = axis[0] * axis[1] * (1 - cosine);
bc = axis[1] * axis[2] * (1 - cosine);
ca = axis[2] * axis[0] * (1 - cosine);
tx = axis[0] * axis[0];
ty = axis[1] * axis[1];
tz = axis[2] * axis[2];
m[0] = tx + cosine * (1 - tx);
m[1] = ab + axis[2] * sine;
m[2] = ca - axis[1] * sine;
m[3] = 0.0f;
m[4] = ab - axis[2] * sine;
m[5] = ty + cosine * (1 - ty);
m[6] = bc + axis[0] * sine;
m[7] = 0.0f;
m[8] = ca + axis[1] * sine;
m[9] = bc - axis[0] * sine;
m[10] = tz + cosine * (1 - tz);
m[11] = 0;
m[12] = 0;
m[13] = 0;
m[14] = 0;
m[15] = 1;
}
static void makeTranslateMatrix(float x, float y, float z, float m[16])
{
m[0] = 1; m[1] = 0; m[2] = 0; m[3] = x;
m[4] = 0; m[5] = 1; m[6] = 0; m[7] = y;
m[8] = 0; m[9] = 0; m[10] = 1; m[11] = z;
m[12] = 0; m[13] = 0; m[14] = 0; m[15] = 1;
}
/* Simple 4x4 matrix by 4x4 matrix multiply. */
static void multMatrix(float dst[16],
const float src1[16], const float src2[16])
{
float tmp[16];
int i, j;
for (i=0; i<4; i++) {
for (j=0; j<4; j++) {
tmp[i*4+j] = src1[i*4+0] * src2[0*4+j] +
src1[i*4+1] * src2[1*4+j] +
src1[i*4+2] * src2[2*4+j] +
src1[i*4+3] * src2[3*4+j];
}
}
/* Copy result to dst (so dst can also be src1 or src2). */
for (i=0; i<16; i++)
dst[i] = tmp[i];
}
static void display(void)
{
float translateMatrix[16], rotateMatrix[16],
modelMatrix[16], viewMatrix[16],
modelViewMatrix[16], modelViewProjMatrix[16];
buildLookAtMatrix(13*sin(myEyeAngle), 0, 13*cos(myEyeAngle), /* eye position */
0, 0, 0, /* view center */
0, 1, 0, /* up vector */
viewMatrix);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
cgGLBindProgram(myCgVertexProgram);
checkForCgError("binding vertex program");
cgGLEnableProfile(myCgVertexProfile);
checkForCgError("enabling vertex profile");
cgGLBindProgram(myCgFragmentProgram);
checkForCgError("binding fragment program");
cgGLEnableProfile(myCgFragmentProfile);
checkForCgError("enabling fragment profile");
/*** Render green wireframe sphere ***/
/* modelView = rotateMatrix * translateMatrix */
makeRotateMatrix(70, 1, 1, 1, rotateMatrix);
makeTranslateMatrix(2, 0, 0, translateMatrix);
multMatrix(modelMatrix, translateMatrix, rotateMatrix);
/* modelViewMatrix = viewMatrix * modelMatrix */
multMatrix(modelViewMatrix, viewMatrix, modelMatrix);
/* modelViewProj = projectionMatrix * modelViewMatrix */
multMatrix(modelViewProjMatrix, myProjectionMatrix, modelViewMatrix);
/* Set matrix parameter with row-major matrix. */
cgSetMatrixParameterfr(myCgVertexParam_modelViewProj, modelViewProjMatrix);
cgSetParameter4f(myCgFragmentParam_c, 0.1,0.7,0.1,1); /* Green */
cgUpdateProgramParameters(myCgVertexProgram);
cgUpdateProgramParameters(myCgFragmentProgram);
glutWireSphere(2.0, 30, 30);
/*** Render red wireframe cone ***/
/* modelView = viewMatrix * translateMatrix */
makeTranslateMatrix(-2, -1.5, 0, translateMatrix);
makeRotateMatrix(90, 1, 0, 0, rotateMatrix);
multMatrix(modelMatrix, translateMatrix, rotateMatrix);
/* modelViewMatrix = viewMatrix * modelMatrix */
multMatrix(modelViewMatrix, viewMatrix, modelMatrix);
/* modelViewProj = projectionMatrix * modelViewMatrix */
multMatrix(modelViewProjMatrix, myProjectionMatrix, modelViewMatrix);
/* Set matrix parameter with row-major matrix. */
cgSetMatrixParameterfr(myCgVertexParam_modelViewProj, modelViewProjMatrix);
cgSetParameter4f(myCgFragmentParam_c, 0.8,0.1,0.1,1); /* Red */
cgUpdateProgramParameters(myCgVertexProgram);
cgUpdateProgramParameters(myCgFragmentProgram);
glutWireCone(1.5, 3.5, 20, 20);
cgGLDisableProfile(myCgVertexProfile);
checkForCgError("disabling vertex profile");
cgGLDisableProfile(myCgFragmentProfile);
checkForCgError("disabling fragment profile");
glutSwapBuffers();
}
static void idle(void)
{
myEyeAngle += 0.008; /* Add a small angle (in radians). */
if (myEyeAngle > 2*myPi) {
myEyeAngle -= 2*myPi;
}
glutPostRedisplay();
}
static void keyboard(unsigned char c, int x, int y)
{
static int animating = 0;
switch (c) {
case ' ':
animating = !animating; /* Toggle */
if (animating) {
glutIdleFunc(idle);
} else {
glutIdleFunc(NULL);
}
break;
case 27: /* Esc key */
/* Demonstrate proper deallocation of Cg runtime data structures.
Not strictly necessary if we are simply going to exit. */
cgDestroyProgram(myCgVertexProgram);
cgDestroyContext(myCgContext);
exit(0);
break;
}
}
static void menu(int item)
{
/* Pass menu item character code to keyboard callback. */
keyboard((unsigned char)item, 0, 0);
}
/* Platform-specific code to request synchronized buffer swaps. */
static void requestSynchronizedSwapBuffers(void)
{
#if defined(__APPLE__)
#ifdef CGL_VERSION_1_2
const GLint sync = 1;
#else
const long sync = 1;
#endif
CGLSetParameter(CGLGetCurrentContext(), kCGLCPSwapInterval, &sync);
#elif defined(_WIN32)
if (wglSwapIntervalEXT) {
wglSwapIntervalEXT(1);
}
#else
if (glXSwapIntervalSGI) {
glXSwapIntervalSGI(1);
}
#endif
}
