world_of_cow/ui.c

#include "ui.h"
#include "vec.h"
#include <GL/freeglut_std.h>
#include <GL/freeglut_ext.h>
#include <GL/glut.h>
#include <GL/gl.h>
#include <stdio.h>

#define BACK_COLOR 0.3, 0.35, 0.35

void ui_slider_draw(ui_slider* s) {
    int wWidth = glutGet(GLUT_WINDOW_WIDTH);
    int wHeight = glutGet(GLUT_WINDOW_HEIGHT);
    
    vec3 pos = vec3_add(s->position.absolute, vec3_new(s->position.relative.x * wWidth, s->position.relative.y * wHeight, 0.0));
    vec3 ext = s->size;
    
    vec3 slider = vec3_add(pos, vec3_new(ext.x * s->value, ext.y * 0.5, 0.0));
    glBegin(GL_QUADS);
        // draw background line
        glColor3f(BACK_COLOR);
        glVertexVec(pos);
        glVertex3f(pos.x + ext.x, pos.y, pos.z);
        glVertex3f(pos.x + ext.x, pos.y + ext.y, pos.z);
        glVertex3f(pos.x, pos.y + ext.y, pos.z);
        // Draw slider button thing
        glColor3f(1.0, 1.0, 1.0);
        glVertex3f(slider.x - ext.z, slider.y - ext.z, 0.0);
        glVertex3f(slider.x + ext.z, slider.y - ext.z, 0.0);
        glVertex3f(slider.x + ext.z, slider.y + ext.z, 0.0);
        glVertex3f(slider.x - ext.z, slider.y + ext.z, 0.0);
    glEnd();
}

char ui_slider_mouse_over(ui_slider* s, int mouseX, int mouseY) {
    int wWidth = glutGet(GLUT_WINDOW_WIDTH);
    int wHeight = glutGet(GLUT_WINDOW_HEIGHT);
    
    vec3 pos = vec3_add(s->position.absolute, vec3_new(s->position.relative.x * wWidth, s->position.relative.y * wHeight, 0.0));
    vec3 ext = s->size;
    vec3 m = vec3_sub(vec3_new(mouseX, wHeight - mouseY - 0.5 * ext.y, 0.0), pos);
    return m.x > 0.0 && m.x < ext.x && m.y > -ext.z && m.y < ext.z;
}

void ui_slider_onclick(ui_slider* s, int mouseX, int mouseY) {
    // we assume mouse  is already hovering
    int wWidth = glutGet(GLUT_WINDOW_WIDTH);
    int wHeight = glutGet(GLUT_WINDOW_HEIGHT);
    
    vec3 pos = vec3_add(s->position.absolute, vec3_new(s->position.relative.x * wWidth, s->position.relative.y * wHeight, 0.0));
    s->value = ((float)mouseX - pos.x) / s->size.x;
}