i am a beginner to opengl following an online guide, I am trying to make a simple translation to my triangle. The triangle did render correctly when i made a float uniform to translate it, but when i multiply a mat4 to translate it, i get a black screen. Opengl outputs no error, i can't tell where is the problem. Here is the code: https://pastebin.com/en2zpPTh

Here's my drawing loop:

//Loop until window close
while (!glfwWindowShouldClose(mainWindow))
    //Get + Handle user input events

    if (direction)
        triOffset += triIncrement;
        triOffset -= triIncrement;

    if (abs(triOffset >= triMaxOffset))
        direction = !direction;

    //Clear window
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);


    glm::mat4 model;
    model = glm::translate(model, glm::vec3(triOffset, 0.0f, 0.0f));

    glUniformMatrix4fv(uniformModel, 1, GL_FALSE, glm::value_ptr(model));

    glDrawArrays(GL_TRIANGLES, 0, 3);



    return 0;

and here's my vertex shader:

// Vertex Shader
static const char* vShader = " \n"
"#version 330                  \n"
"layout (location = 0) in vec3 pos;\n"
"uniform mat4 model;                        \n"
"void main()\n"
"   gl_Position = model * vec4(pos, 1.0);\n"

And fragment shader:

//Fragment shader
static const char* fShader =  " \n"
"#version 330                  \n"
"out vec4 color;               \n"
"void main()\n"
"   color = vec4(1.0, 1.0, 0.5, 1.0);\n"
  • $\begingroup$ uniformModel = glGetUniformLocation(shader, "model"); << Do you call glUseProgram(..) before this call ? High up on my checklist would be to see if the uniform was bound correctly. $\endgroup$ – PaulHK Jun 26 '18 at 3:48
  • $\begingroup$ There is definitly a problem with the matrix, because it is not set to an identity matrix, even when i call glm::mat4 model = glm::mat4(); , so the translation isn't happening, and the triangle is not drawn. $\endgroup$ – Nathan Lenas Jun 26 '18 at 9:48
  • $\begingroup$ Yes i added the glUseProgram(shader); before ;uniformModel = glGetUniformLocation(shader, "model"); but i think now the problem is on the cpu side because when i breakpoint the render loop the matrix is always [0,0,0,0] instead of identity matrix $\endgroup$ – Nathan Lenas Jun 26 '18 at 9:57

We fixed it ! it was glm::mat4(); no initializing to a identity matrix, glm::mat4(1.0f); works fine, thank you for helping me !


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