Code: 3d_underwater_world/fish.cpp

This is an example OpenGL SDL application which creates an animated 3D underwater world (screenshot), with "Thunderbird 4" with headlights moving on a spline path, a randomly generated sand terrain, sunken ship/submarine/treasure chest models, and swaying fish and seaweed. It is designed to demonstrate basic OpenGL features, and the structure is as follows:

#include "worldobjects.h"
#include "vectors.h"

#define MIN_X 0.0
#define MIN_Y 3.0
#define MIN_Z 0.0
#define MAX_X 100.0
#define MAX_Y 30.0
#define MAX_Z 100.0

#define TEX_COUNT 4

// calculate a random float between
// 0.0 and ran.
inline GLfloat randf(GLfloat min, GLfloat max) {
    // calculate between 0 and 1
    int ir = rand() % 1000;
    GLfloat v = ((float)(ir) / 1000.0f);
    // change to range
    return (v * (max - min)) + min;
}

// init textures
Texture** FishObject::textures;
void FishObject::initTextures()
{
    FishObject::textures = new Texture*[TEX_COUNT];
    for (int i = 0; i < TEX_COUNT; i++) {
        char txt[] = "fish0.jpg";
        sprintf(txt, "fish%i.jpg", i);
        FishObject::textures[i] = new Texture(txt);
    }
}

// constructor
FishObject::FishObject()
{
    // random location on map
    loc.x = randf(MIN_X, MAX_X);
    loc.y = randf(MIN_Y, MAX_Y);
    loc.z = randf(MIN_Z, MAX_Z);
    pos.x = loc.x;
    pos.y = loc.y;
    pos.z = loc.z;
    // random bearing
    bearing = randf(0, 360);
    // random texture
    tex = rand() % TEX_COUNT;
    if (tex == 4 && rand()%4 != 0) tex = rand() % TEX_COUNT;
    // random size
    if (tex == 4) {
        // shark
        w = randf(3.5,4);
        h = randf(1,1.5);
        s = randf(1, 3);
        moving = true;
        v = randf(0.2, 10);
    } else {
        // other fish
        w = randf(2, 3);
        h = randf(0.5, 1);
        s = randf(0.1, 0.8);
        // moving?
        if (randf(0, 1) < 0.5) moving = true;
        else moving = false;
        v = randf(0.05, 10);
    }
}

// draw
void FishObject::drawMesh()
{
     glColor3f(1, 1, 1);
     glDisable(GL_LIGHTING);
    Texture* t = FishObject::textures[tex];
    t->Begin();
    //GLfloat cl[] = {1.0, 0, 0, 0, 0};
    //glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND);
    //glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, cl);
    //glColor3f(0.2, 0.2, 1);
    glPushMatrix();
    glRotatef(bearing, 0, 1, 0);
    glScalef(1, h, w);
    glScalef(s, s, s);
    //Primitives::drawSphere();
    
    glBegin(GL_QUADS);
    glTexCoord2f(t->minX(), t->maxY());
    glVertex3f(0, 0, 0);
    glTexCoord2f(t->maxX(), t->maxY());
    glVertex3f(0, 0, 1);
        glTexCoord2f(t->maxX(), t->minY());
    glVertex3f(0, 1, 1);
    glTexCoord2f(t->minX(), t->minY());
    glVertex3f(0, 1, 0);
    glEnd();
    
    glPopMatrix();
    //glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    t->End();
    glEnable(GL_LIGHTING);
}

// simulate
void FishObject::simulate(GLfloat dT)
{
     time += dT;
     // wave in the current
     pos.x = loc.x + sin(time);
     // move along vector
     if (moving) {
         Vec3 dir;
         dir.z += v * dT;
         Mat4 m;
         m.rotate(bearing + 90, 0, 1, 0);
         m.transform(&dir);
         pos.add(&dir);
     }
     // check if out of bounds
     if (pos.x > MAX_X) pos.x = MIN_X;
     else if (pos.x < MIN_X) pos.x = MAX_X;
     if (pos.y > MAX_Y) pos.y = MIN_Y;
     else if (pos.y < MIN_Y) pos.y = MAX_Y;
     if (pos.z > MAX_Z) pos.z = MIN_Z;
     else if (pos.z < MIN_Z) pos.z = MAX_Z;
}

3D Underwater World (using OpenGL and SDL)

fish.cpp