Messages

1

General / Re: OpenGL basic program triangle isn't visible

« on: September 08, 2017, 04:14:04 pm »

`sudo lspci -vnn | grep VGA -A 12` (GPU)

Output:

00:02.0 VGA compatible controller [0300]: Intel Corporation Broadwell-U Integrated Graphics [8086:1616] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Acer Incorporated [ALI] Device [1025:0899]
   Flags: bus master, fast devsel, latency 0, IRQ 48
   Memory at c0000000 (64-bit, non-prefetchable) [size=16M]
   Memory at b0000000 (64-bit, prefetchable) [size=256M]
   I/O ports at 4000 [size=64]
   [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
   Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
   Capabilities: [d0] Power Management version 2
   Capabilities: [a4] PCI Advanced Features
   Kernel driver in use: i915

00:03.0 Audio device [0403]: Intel Corporation Broadwell-U Audio Controller [8086:160c] (rev 09)

---

glew.cpp (117) glCheckError();
glew.cpp (123) glCheckError();

jamesL's code defined a macro so glCheckError() calls glCheckError_(const char* file, int line)

2

General / Re: OpenGL basic program triangle isn't visible

« on: September 08, 2017, 11:38:46 am »

I ran the code (had to comment out the two lines relating to attribute flags since I have SFML 2.1). The result is the same (black screen) and the output is this:

version: 3.0
depth bits: 24
stencil bits: 8
antialiasing level: 0
INVALID OPERATION | glew.cpp (117)
INVALID OPERATION | glew.cpp (123)

3

General / Re: OpenGL basic program triangle isn't visible

« on: September 07, 2017, 03:34:24 pm »

I tried that, but I still get a black screen. Is there a complete example (code) for drawing a triangle with SFML and OpenGL 3.0 (no immediate mode)? I'm starting to think the problem is with my laptop/OS.

4

General / Re: OpenGL basic program triangle isn't visible

« on: September 06, 2017, 11:37:55 am »

So I installed glew `sudo aptitude install libglew-dev`and copy/pasted the code. When I run it the same thing happens (black screen, no triangle). Any ideas?

5

General / Re: OpenGL basic program triangle isn't visible

« on: September 06, 2017, 01:21:48 am »

I don't have glew but I will install it and try to run the original code.

6

General / OpenGL basic program triangle isn't visible

« on: September 05, 2017, 05:06:57 pm »

Following this tutorial https://open.gl/ (specifically this one: https://open.gl/drawing) I tried to compile my first OpenGL program. The program is supposed to show a triangle on the screen. I'm not sure if this is a problem about SFML or OpenGL. When I run the code nothing is shown (just a black screen). What needs to be changed to display the triangle correctly?

SFML version: 2.1
OpenGL version used (checked in windows.getSettings()): 3.0
OS: Linux (Debian Jessie 8.7) 64-bit

#include <SFML/Window.hpp>
#include <SFML/OpenGL.hpp>
#include <vector>

int main()
{
    sf::ContextSettings settings;
    settings.depthBits = 24;
    settings.stencilBits = 8;
    settings.antialiasingLevel = 2;
    settings.majorVersion = 3;
    settings.minorVersion = 2;
    sf::Window window{sf::VideoMode{800, 600}, "opengl", sf::Style::Default, settings};
    window.setActive();

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

    std::vector<float> vertices
    {
        0.0f, 0.5f,
        0.5f, -0.5f,
        -0.5f, -0.5f
    };
    GLuint vbo;
    glGenBuffers(1, &vbo);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, vertices.size(), &vertices[0], GL_STATIC_DRAW);

    const char* vertexSource
    {
        R"glsl(
            #version 150 core
            in vec2 position;
            void main()
            {
                gl_Position = vec4(position, 0.0, 1.0);
            }
        )glsl"
    };
    GLuint vertexShader{glCreateShader(GL_VERTEX_SHADER)};
    glShaderSource(vertexShader, 1, &vertexSource, nullptr);
    glCompileShader(vertexShader);

    const char* fragmentSource
    {
        R"glsl(
            #version 150 core
            out vec4 outColor;
            void main()
            {
                outColor = vec4(1.0, 1.0, 1.0, 1.0);
            }
        )glsl"
    };
    GLuint fragmentShader{glCreateShader(GL_FRAGMENT_SHADER)};
    glShaderSource(fragmentShader, 1, &fragmentSource, nullptr);
    glCompileShader(fragmentShader);

    GLuint shaderProgram{glCreateProgram()};
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glBindFragDataLocation(shaderProgram, 0, "outColor");
    glLinkProgram(shaderProgram);
    glUseProgram(shaderProgram);

    GLint posAttrib{glGetAttribLocation(shaderProgram, "position")};
    glEnableVertexAttribArray(posAttrib);
    glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);

    bool running{true};
    while (running)
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                running = false;
            else if (event.type == sf::Event::KeyPressed)
                if (event.key.code == sf::Keyboard::Return)
                    running = false;
        }
        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glDrawArrays(GL_TRIANGLES, 0, 3);
        window.display();
    }

    glDeleteProgram(shaderProgram);
    glDeleteShader(fragmentShader);
    glDeleteShader(vertexShader);
    glDeleteBuffers(1, &vbo);
    glDeleteVertexArrays(1, &vao);
    window.close();
}
 

7

Graphics / Re: Boundaries of X, Y coordinates in window

« on: August 15, 2017, 04:15:09 pm »

Thanks a lot!

8

Graphics / Boundaries of X, Y coordinates in window

« on: August 15, 2017, 03:36:01 pm »

In this code:

#include <SFML/Graphics.hpp>

int main()
{
    sf::RenderWindow window{sf::VideoMode{300, 300}, "Window Title"};

    sf::VertexArray points{sf::Points, 4};

    // which two of these are the top left and bottom right corner

    points[0].position = sf::Vector2f{0, 0};
    points[1].position = sf::Vector2f{1, 1};
    points[2].position = sf::Vector2f{299,  299};
    points[3].position = sf::Vector2f{300, 300};

    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
            if (event.type == sf::Event::Closed)
                window.close();
        window.clear(); window.draw(points); window.display();
    }
}

What are the boundaries? 0-299 or 1-300 (width or height)? Also, the question in the comment.