gistfile1.c

#include <string>
#include <cstdio>
#include <cmath>

#include "GL/glfw.h"
#include "SOIL.h"

// function declarations
void drawscene();
void updatedisplay();

class Texture {
public:
    Texture() :
        texture(0),
        width(0), height(0),
        channels(0) {
    
    }

    Texture(const char *filename) {
        load_filename(filename);
    }
    
    void load_filename(const char *filename) {
        unsigned char *data = SOIL_load_image(filename, &width, &height, &channels, SOIL_LOAD_AUTO);
        
        texture = SOIL_create_OGL_texture(data, width, height, channels, 0, SOIL_FLAG_POWER_OF_TWO | SOIL_FLAG_MULTIPLY_ALPHA);
        
        SOIL_free_image_data(data);
    }
    
public:
    GLuint texture;
    int width;
    int height;
    int channels;
};

class Sprite {
public:
    Sprite() :
        x(0), y(0),
        anchor_x(0), anchor_y(0),
        rotation(0.0), scale(0.0),
        texture(0) {
        
    }
    
    Sprite(GLuint tex) :
        x(0), y(0),
        anchor_x(0), anchor_y(0),
        rotation(0.0), scale(0.0),
        texture(tex) {
        
    }
    
    Sprite(const Sprite& sprite) :
        x(sprite.x), y(sprite.y),
        anchor_x(sprite.anchor_x), anchor_y(sprite.anchor_y),
        rotation(sprite.rotation), scale(sprite.rotation),
        texture(sprite.texture) {
    
    }
    
    void draw() {
        if (!texture) return;
        
        glBindTexture(GL_TEXTURE_2D, texture);
        
        glPushMatrix();
            glTranslatef((GLfloat) x, (GLfloat) y, 0);
            glTranslatef((GLfloat) anchor_x, (GLfloat) anchor_y, 0);
            glRotatef((GLfloat) rotation, 0.0f, 0.0f, 1.0f);
            glScalef(scale, scale, 1.0f);
            glTranslatef((GLfloat) -anchor_x, (GLfloat) -anchor_y, 0);
            
            glBegin(GL_QUADS);
                glTexCoord2f(0.0f, 0.0f);
                glVertex2f(0.0f, 0.0f);
                glTexCoord2f(0.0f, 1.0f);
                glVertex2f(0.0f, 128.0f);
                glTexCoord2f(1.0f, 1.0f);
                glVertex2f(128.0f, 128.0f);
                glTexCoord2f(1.0f, 0.0f);
                glVertex2f(128.0f, 0.0f);
            glEnd();
        glPopMatrix();
    }
    
    int x;
    int y;
    int anchor_x;
    int anchor_y;
    float rotation;
    float scale;

private:
    GLuint texture;
};

Texture tex;

int main(int argc, char **argv) {
    if (!glfwInit()) {
        fprintf(stderr, "Failed to initialize GLFW\n");
        return 1;
    }
    
    if (!glfwOpenWindow(640, 480, 0, 0, 0, 0, 16, 0, GLFW_WINDOW)) {
        fprintf(stderr, "Failed to open GLFW window\n");
        return 1;
    }
    
    // enable vsync (if available)
    glfwSwapInterval(1);
    
    // load textures
    tex.load_filename("tex.png");
    
    //texture = SOIL_load_OGL_texture(
    //    "tex.png",
    //    SOIL_LOAD_AUTO,
    //    SOIL_CREATE_NEW_ID,
    //    SOIL_FLAG_POWER_OF_TWO | SOIL_FLAG_MIPMAPS | SOIL_FLAG_DDS_LOAD_DIRECT
	//);
	
    // check for an error during the texture loading
    //if (!texture) {
    //    printf("SOIL loading error: '%s'\n", SOIL_last_result());
    //}

    while (glfwGetWindowParam(GLFW_OPENED)) {
        updatedisplay();
        drawscene();
    }

    // if we get here something went wrong
    return 0;
}

// set up te display
void updatedisplay() {
    int screen_width, screen_height;
    glfwGetWindowSize(&screen_width, &screen_height);

    if (screen_height <= 0) screen_height = 1;
    if (screen_width <= 0) screen_width = 1;

    glViewport(0, 0, screen_width, screen_height);
    
    glClearColor(1, 1, 1, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    
    glEnable(GL_TEXTURE_2D);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glEnable(GL_BLEND);
    glDisable(GL_DEPTH_TEST);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, screen_width, screen_height, 0.0, 0.0, 1.0);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    // displacement trick for exact pixelization
    glTranslatef(0.375f, 0.375f, 0.0f);
}

// draw the scene in this function
void drawscene() {
    static float delta = 0.0;
    delta += 0.1;
    
    Sprite sprite(tex.texture);
    sprite.x = 150;
    sprite.y = 150;
    sprite.anchor_x = 64;
    sprite.anchor_y = 64;
    sprite.rotation = delta * 2;
    sprite.scale = fmod(delta / 20, 2.0);
    sprite.draw();

    glfwSwapBuffers();
}