world_of_cow/mmn_17.c

#include <GL/freeglut.h>
#include <GL/freeglut_std.h>
#include <GL/gl.h>
#include <GL/glext.h>
#include <GL/glu.h>
#include <stdio.h>
#include <math.h>
#include "ui.h"
#include "grass_texture_color.h"
// close enough
#define PI 3.14


// Camera rotation and stuff
float camRadius = 10.0;
vec3 camCenter = { 0.0, 0.0, 0.0 };
vec3 camRot = { -PI * 0.125, 0.0, 0.0 };
struct { 
    unsigned char lockYMovement: 1;
    GLenum textureFilter;
} settings = {
    0, GL_NEAREST, 
};

vec3 rotateByCameraRotation(vec3 v) {
    vec3 r;
    // rotate along the x axis(yz plane)
    r.z = cosf(camRot.x) * v.z + sinf(camRot.x) * v.y;
    r.y = -sinf(camRot.x) * v.z + cosf(camRot.x) * v.y;
    v = r;
    // rotate along the y axis(xy plane)
    r.z = cosf(camRot.y) * v.z + sinf(camRot.y) * v.x;
    r.x = -sinf(camRot.y) * v.z + cosf(camRot.y) * v.x;
    return r;
}

// Ui stuff
int lastMouseButton = GLUT_LEFT_BUTTON;
int lastMouseX = 0, lastMouseY = 0;
ui_slider* draggedSlider = NULL;
void changeFilterButton();
void lockYButton();
ui_button buttons[] = {
    { 
            /* pos */ { { 0.9, 0.5, 0.0 }, { -65.0, -20.0, 0.0 } },
            /* size */ { 130.0, 40.0, 0.0 },
            /* onclick */ changeFilterButton,
            /* text */ "Cycle filter",
            0
        },
        {
            { { 0.9, 0.5, 0.0 }, { -50.0, 25.0, 0.0 } },
            { 100.0, 40.0, 0.0 },
            lockYButton,
            "Lock Y"
        }
};
ui_slider sliders[] = {
    {
        /* pos */ { { 0.9, 0.7, 0.0 }, { -50.0, -5.0, 0.0 } },
        /* size */ { 100.0, 10.0, 10.0 },
        0.1
    }
};

void changeFilterButton() {
    static int current = 0;
    GLenum filters[] = { GL_NEAREST, GL_LINEAR };
    current = (current + 1) % (sizeof(filters) / sizeof(GLenum));
    settings.textureFilter = filters[current];
    glutPostRedisplay();
}
void lockYButton() {
    settings.lockYMovement ^= 1;
    buttons[1].text = settings.lockYMovement ? "Unlock Y" : "Lock Y";
}

void drawUi(void) {
    glDisable(GL_LIGHTING);
    glDisable(GL_DEPTH_TEST);
    
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    // set ui camera
    int wWidth = glutGet(GLUT_WINDOW_WIDTH);
    int wHeight = glutGet(GLUT_WINDOW_HEIGHT);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0.0, wWidth, 0.0, wHeight);
    
    // Draw buttons
    for(ui_button* b = buttons; b < buttons + sizeof buttons / sizeof(ui_button); b += 1) {
        ui_button_draw(b);
    }
    for(ui_slider* s = sliders; s < sliders + sizeof sliders / sizeof(ui_slider); s += 1) {
        ui_slider_draw(s);
    }
    
    int err = glGetError();
    if(err != 0) {
        printf("opengl error %d: %s\n", err, gluErrorString(err));
    }
}

void drawWorld(void) {
    glEnable(GL_DEPTH_TEST);
    
    // set perspective camera
    GLdouble wWidth = (GLdouble) glutGet(GLUT_WINDOW_WIDTH);
    GLdouble wHeight = (GLdouble) glutGet(GLUT_WINDOW_HEIGHT);
    // Calculate current camera position from rotation
    vec3 cp = vec3_new(0.0, 0.0, camRadius);
    cp = rotateByCameraRotation(cp);
    cp = vec3_add(cp, camCenter);
    vec3 up = rotateByCameraRotation(vec3_new(0.0, 1.0, 0.0));
    
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(cp.x, cp.y, cp.z, camCenter.x, camCenter.y, camCenter.z, up.x, up.y, up.z);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(90, wWidth / wHeight  , 1.0, 500.0);
    // Lights
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    // Directional light - aka light
    GLfloat light1[] = { 0.0, 1.0, 0.0, 0.0 };
    glLightfv(GL_LIGHT0, GL_POSITION, light1);
    // World
    // Ground
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, settings.textureFilter);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, settings.textureFilter);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 128, 128, 0, GL_RGBA, GL_UNSIGNED_BYTE, grass_color_128);
    glEnable(GL_TEXTURE_2D);
    glBegin(GL_QUADS);
        glColor3f(1.0, 1.0, 0.0);
        glNormal3f(0.0, 5.0, 0.0);
        glTexCoord2f(0.0, 0.0); glVertex3f(-50.0, 0.0, -50.0);
        glTexCoord2f(0.0, 1.0); glVertex3f(-50.0, 0.0, 50.0);
        glTexCoord2f(1.0, 1.0); glVertex3f(50.0, 0.0, 50.0);
        glTexCoord2f(1.0, 0.0); glVertex3f(50.0, 0.0, -50.0);
    glEnd();
    glDisable(GL_TEXTURE_2D);
    
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glTranslatef(0.0, 5.0, 0.0);
    glScalef(3.0, 3.0, 3.0);
    glColor3f(1.0, 1.0, 1.0);
    glutSolidDodecahedron();
    glPopMatrix();
}

void display(void) {
    // Clear screen
    glClearColor(0.0, 0.0, 0.0, 1.0); // Dark theme :)
    glClear(GL_COLOR_BUFFER_BIT);
    glClear(GL_DEPTH_BUFFER_BIT);

    drawWorld();
    drawUi();

    glutSwapBuffers();
    glFlush();
}

void mouseEvent(int button, int state, int x, int y) {
    lastMouseX = x; lastMouseY = y;
    if(state == 0) lastMouseButton = button;
    if(state == 0 && button == GLUT_LEFT_BUTTON) {
        for(ui_button* b = buttons; b < buttons + sizeof buttons / sizeof(ui_button); b += 1) {
            if(ui_button_mouse_over(b, x, y) && b->onClick != NULL) {
                b->clicked = 1;
            }
        }
        for(ui_slider* s = sliders; s < sliders + sizeof sliders / sizeof(ui_slider); s += 1) {
            if(ui_slider_mouse_over(s, x, y)) {
                ui_slider_onclick(s, x, y);
                draggedSlider = s;
            }
        }
    }
    else if(state == 1 && button == GLUT_LEFT_BUTTON) {
        draggedSlider = NULL;
        for(ui_button* b = buttons; b < buttons + sizeof buttons / sizeof(ui_button); b += 1) {
            b->clicked = 0;
            if(ui_button_mouse_over(b, x, y) && b->onClick != NULL) {
                b->onClick();
            }
        }
    }
    glutPostRedisplay();
}

void mouseMotionEvent(int x, int y) {
    if(lastMouseButton == GLUT_LEFT_BUTTON) {
        if(draggedSlider != NULL) {
            if(ui_slider_mouse_over(draggedSlider, x, y)) {
                ui_slider_onclick(draggedSlider, x, y);
            }
        }
    }
    else if(lastMouseButton == GLUT_MIDDLE_BUTTON) {
        vec3 moveX = rotateByCameraRotation(vec3_new(1.0, 0.0, 0.0));
        vec3 moveY = rotateByCameraRotation(vec3_new(0.0, 1.0, 0.0));
        
        if(settings.lockYMovement) {
            moveX.y = 0;
            moveY.y = 0;
        }
        
        camCenter = vec3_add(camCenter, vec3_mult(moveX, (lastMouseX - x)));
        camCenter = vec3_add(camCenter, vec3_mult(moveY, (y - lastMouseY)));
    }
    else if(lastMouseButton == GLUT_RIGHT_BUTTON) {
        // rotate the camera
        camRot.y -= (x - lastMouseX) * PI * 0.01;
        if(camRot.y > 2 * PI) camRot.y -= 2 * PI;
        else if(camRot.y < 0.0) camRot.y += 2 * PI;
        
        camRot.x = fmin(PI * 0.5, fmax(-PI * 0.5, camRot.x - (y - lastMouseY) * 0.01 * PI));
    }
    lastMouseX = x; lastMouseY = y;
    glutPostRedisplay();
}

void mouseWheelEvent(int wheel, int dir, int x, int y) {
    char slided = 0;
    for(ui_slider* s = sliders; s < sliders + sizeof sliders / sizeof(ui_slider); s += 1) {
        if(ui_slider_mouse_over(s, x, y)) {
            s->value += dir * 0.05;
            if(s->value < 0.0) s->value = 0.0;
            if(s->value > 1.0) s->value = 1.0;
            slided = 1;
        }
    }
    if(!slided) {
        camRadius *= 1.0 - (dir * 0.1);
    }
    glutPostRedisplay();
}

void keyboardEvent(unsigned char c, int x, int y) {
    if(c == '\e') {
        glutLeaveMainLoop();
        exit(0);
    }
    if(c == 'a') {
        glutPostRedisplay();
    }
}

int main(int argc, char** argv) {
    /* initialize glut and window */
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(800, 500);
    glutInitWindowPosition(450, 450);
    /* create window and set callbacks */
    glutCreateWindow("World of Cow");
    glutDisplayFunc(display);
    glutMouseFunc(mouseEvent);
    glutKeyboardFunc(keyboardEvent);
    glutMouseWheelFunc(mouseWheelEvent);
    glutMotionFunc(mouseMotionEvent);
    // set up some rendering related stuff
    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);

    glutMainLoop();

    return 0;
}