shader_triangle.cpp

#include <SFML/Window.hpp>
#include <glload/gl_3_3.h>
#include <glload/gll.h>

#include <vector>

#include "util.h"

GLuint theProgram;

const float vertexPositions[] = {
	0.75f, 0.75f, 0.0f, 1.0f,
	0.75f, -0.75f, 0.0f, 1.0f,
	-0.75f, -0.75f, 0.0f, 1.0f,
};

GLuint positionBufferObject;
GLuint vao;

const std::string strVertexShader(
	"#version 330\n"
	"layout(location = 0) in vec4 position;\n"
	"void main()\n"
	"{\n"
	"    gl_Position = position;\n"
	"}\n"
);

const std::string strFragmentShader(
	"#version 330\n"
	"out vec4 outputColor;\n"
	"void main()\n"
	"{\n"
	"    outputColor = vec4(1.0f, 1.0f, 1.0f, 1.0f);\n"
	"}\n"
);

void initialize()
{
	// Initialize Shader Program
	std::vector<GLuint> shaderList;
	shaderList.push_back(CreateShader(GL_VERTEX_SHADER, strVertexShader));
	shaderList.push_back(CreateShader(GL_FRAGMENT_SHADER, strFragmentShader));
	theProgram = CreateProgram(shaderList);
	std::for_each(shaderList.begin(), shaderList.end(), glDeleteShader);

	// Initialize Vertex Buffer
	glGenBuffers(1, &positionBufferObject);
	glBindBuffer(GL_ARRAY_BUFFER, positionBufferObject);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertexPositions), vertexPositions, GL_STATIC_DRAW);
	glBindBuffer(GL_ARRAY_BUFFER, 0);

	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);
}

void render()
{
	glClearColor(0, 0, 0, 0);
	glClear(GL_COLOR_BUFFER_BIT);

	glUseProgram(theProgram);

	glBindBuffer(GL_ARRAY_BUFFER, positionBufferObject);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);

	glDrawArrays(GL_TRIANGLES, 0, 3);

	glDisableVertexAttribArray(0);
	glUseProgram(0);
}

void reshape(int w, int h)
{
	glViewport(0, 0, w, h);
}

int main(int argc, char *argv[])
{
	sf::Window window(sf::VideoMode(800, 600, 32), "OpenGL Template");
	sf::Clock timer;

	if (LoadFunctions() == LS_LOAD_FAILED)
		return 1;

	initialize();

	int now = timer.getElapsedTime().asMilliseconds();
	int last = now;
	
	reshape(window.getSize().x, window.getSize().y);

	while (window.isOpen()) {
		sf::Event event;
		while (window.pollEvent(event)) {
			switch (event.type) {
			case sf::Event::Closed:
				window.close();
				break;
			case sf::Event::Resized:
				reshape(window.getSize().x, window.getSize().y);
				break;
			}
		}

		render();

		window.display();
	}

	return 0;
}