gltest.c

#include <GLFW/glfw3.h>
#include <stdlib.h>
#include <stdio.h>


static void error_callback(int error, const char* description)
{
	fputs(description, stderr);
}
static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
		glfwSetWindowShouldClose(window, GL_TRUE);
}
int main(void)
{
	GLFWwindow* window;
	glfwSetErrorCallback(error_callback);
	if (!glfwInit())
		exit(EXIT_FAILURE);
	window = glfwCreateWindow(512, 512, "Simple example", NULL, NULL);
	if (!window)
	{
		glfwTerminate();
		exit(EXIT_FAILURE);
	}
	glfwMakeContextCurrent(window);
	glfwSetKeyCallback(window, key_callback);

	int width, height;
	glfwGetFramebufferSize(window, &width, &height);

	glEnable(GL_TEXTURE_2D);
	int texture[1];

	glGenTextures(1, &texture[0]);
    glBindTexture(GL_TEXTURE_2D, texture[0]);   // 2d texture (x and y size)

    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); // scale linearly when image bigger than texture
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); // scale linearly when image smalled than texture

    // 2d texture, level of detail 0 (normal), 3 components (red, green, blue), x size from image, y size from image, 
    // border 0 (normal), rgb color data, unsigned byte data, and finally the data itself.
    glTexImage2D(GL_TEXTURE_2D, 0, 3, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);


	while (!glfwWindowShouldClose(window))
	{
		float ratio;
		ratio = width / (float) height;
		glViewport(0, 0, width, height);
		glClear(GL_COLOR_BUFFER_BIT);
		glMatrixMode(GL_PROJECTION);
		glLoadIdentity();
		glOrtho(-ratio, ratio, -1.f, 1.f, 1.f, -1.f);
		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity();
		glRotatef(0.f, 0.f, 0.f, 1.f);
		glBindTexture(GL_TEXTURE_2D, texture[0]);
		glBegin(GL_QUADS);
			glColor3f(1.f, 0.f, 0.f);
			glVertex3f(-1.f, -1.f, 0.f);
			glColor3f(0.f, 1.f, 0.f);
			glVertex3f(-1.f, 1.f, 0.f);
			glColor3f(0.f, 0.f, 1.f);
			glVertex3f(1.f, 1.f, 0.f);
			glColor3f(0.f, 0.f, 1.f);
			glVertex3f(1.f, -1.f, 0.f);
		glEnd();
		glfwSwapBuffers(window);
		glfwPollEvents();
	}
	glfwDestroyWindow(window);
	glfwTerminate();
	exit(EXIT_SUCCESS);
}