Sign in to follow this  

OpenGL Model turns all black in shader

Recommended Posts

In both Rendermonkey and Shaderdesigner programs used for testing glsl shading, I get a complete black model while I'm trying to learn and test different shaders. Image: This image shows the black model in Shaderdesigner, with the following vertex and fragment files:

out vec4 color; void main(void)


  color = gl_Color;

  vec4 v = vec4(gl_Vertex); 

  v.z = sin(5.0*v.x )*0.25;


  gl_Position = gl_ModelViewProjectionMatrix * v;




in vec4 color;

void main()


gl_FragColor = color;



What I think is happening, is the shaderdesigner is send the gl_Color from the opengl application to the shader with a black value, and I have no clue how to change that value. I have tried messing around with ALL the menus, options, anything relates to changing color and nothing is working. Why is my model black and how can I fix it?

Share this post

Link to post
Share on other sites

If its for testing purpose only, why don't you just hard-code the value for gl_Color (or give it some initial value other than 0.0f)? Having one single color supplied to a mesh is not such a huge feature in game developement (as far as I'm concerned) that you do not necessary need to know how to change that. If setting gl_Color in the shader doesn't help, you at least know there is a problem somewhere else.


EDIT: not that there is anything wrong with you wanting to know that, just so you don't have to wait for hours until someone answers but can go on in the meanwhile ^^

Edited by Juliean

Share this post

Link to post
Share on other sites


Yeah, using a constant color works fine, but I would still like to know how to change gl_Color's default value of black.

Share this post

Link to post
Share on other sites

I don't know that you can change the default color from black.. maybe using glColor call in your app.. but why not just make a uniform in your fragment shader to set the color how you want.. you can use the format like this in your fragment shader...



uniform vec4 customColor;




and then in your code set the uniform with gl calls...



Vec4Df colorVec = (1.0f,0.0f,0.0f,1.0f); // red
GLuint varIndex = glGetUniformLocation( progID, customColor);  // where progID is the GLuint program ID given to your shader when you compiled it
glUniform4fv(varIndex, 1, colorVec);

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Partner Spotlight

  • Forum Statistics

    • Total Topics
    • Total Posts
  • Similar Content

    • By xhcao
      Before using void glBindImageTexture(    GLuint unit, GLuint texture, GLint level, GLboolean layered, GLint layer, GLenum access, GLenum format), does need to make sure that texture is completeness. 
    • By cebugdev
      hi guys, 
      are there any books, link online or any other resources that discusses on how to build special effects such as magic, lightning, etc. in OpenGL? i mean, yeah most of them are using particles but im looking for resources specifically on how to manipulate the particles to look like an effect that can be use for games,. i did fire particle before, and I want to learn how to do the other 'magic' as well.
      Like are there one book or link(cant find in google) that atleast featured how to make different particle effects in OpenGL (or DirectX)? If there is no one stop shop for it, maybe ill just look for some tips on how to make a particle engine that is flexible enough to enable me to design different effects/magic 
      let me know if you guys have recommendations.
      Thank you in advance!
    • By dud3
      How do we rotate the camera around x axis 360 degrees, without having the strange effect as in my video below? 
      Mine behaves exactly the same way spherical coordinates would, I'm using euler angles.
      Tried googling, but couldn't find a proper answer, guessing I don't know what exactly to google for, googled 'rotate 360 around x axis', got no proper answers.
      The video shows the difference between blender and my rotation:
    • By Defend
      I've had a Google around for this but haven't yet found some solid advice. There is a lot of "it depends", but I'm not sure on what.
      My question is what's a good rule of thumb to follow when it comes to creating/using VBOs & VAOs? As in, when should I use multiple or when should I not? My understanding so far is that if I need a new VBO, then I need a new VAO. So when it comes to rendering multiple objects I can either:
      * make lots of VAO/VBO pairs and flip through them to render different objects, or
      * make one big VBO and jump around its memory to render different objects. 
      I also understand that if I need to render objects with different vertex attributes, then a new VAO is necessary in this case.
      If that "it depends" really is quite variable, what's best for a beginner with OpenGL, assuming that better approaches can be learnt later with better understanding?
    • By test opty
      Hello all,
      On my Windows 7 x64 machine I wrote the code below on VS 2017 and ran it.
      #include <glad/glad.h>  #include <GLFW/glfw3.h> #include <std_lib_facilities_4.h> using namespace std; void framebuffer_size_callback(GLFWwindow* window , int width, int height) {     glViewport(0, 0, width, height); } //****************************** void processInput(GLFWwindow* window) {     if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)         glfwSetWindowShouldClose(window, true); } //********************************* int main() {     glfwInit();     glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);     glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);     glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);     //glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);     GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", nullptr, nullptr);     if (window == nullptr)     {         cout << "Failed to create GLFW window" << endl;         glfwTerminate();         return -1;     }     glfwMakeContextCurrent(window);     if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))     {         cout << "Failed to initialize GLAD" << endl;         return -1;     }     glViewport(0, 0, 600, 480);     glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);     glClearColor(0.2f, 0.3f, 0.3f, 1.0f);     glClear(GL_COLOR_BUFFER_BIT);     while (!glfwWindowShouldClose(window))     {         processInput(window);         glfwSwapBuffers(window);         glfwPollEvents();     }     glfwTerminate();     return 0; }  
      The result should be a fixed dark green-blueish color as the end of here. But the color of my window turns from black to green-blueish repeatedly in high speed! I thought it might be a problem with my Graphics card driver but I've updated it and it's: NVIDIA GeForce GTX 750 Ti.
      What is the problem and how to solve it please?
  • Popular Now