How to use the ambient color of the material instead of the global ambient color of lights? (OpenGL 1)

Question

I'm writting the lighting effect of my programming in OpenGL 1.1. The light and normals stuffs works. I have only a wrong color

I would like to use the ambient color of the used material but not the global ambient light.

When I use this code, I have a dark grey(64, 64, 64) for light-hidden face but never black (0, 0, 0).

This is the pseudo code :

void Init()
{
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
SetAmbientLight(64, 64, 64); // global value
material.ambientColor = VECTOR3F(0,0,0); // black color, other are default values of OpenGL
}

void SetAmbientLight(U8 r, U8 g, U8 b)
{
    //  Ambient Light is a global value
    const GLfloat inv = 1.0f / 255.0f;
    const GLfloat ambientColor[] = {r * inv, g * inv, b * inv, 1.0f};
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambientColor);
}


void Render()
{
    UseMaterial(material);
    RenderTexturedObject();
    UseMaterial(NULL);
    UseLights();
}

void UseMaterial(MATERIAL *materialdata)
{
    if (materialdata)
    {
        const VECTOR3F& ambiantColor = materialdata->ambiantColor;
        const VECTOR3F& diffuseColor = materialdata->diffuseColor;
        const VECTOR3F& specularColor = materialdata->specularColor;
        const float& shiness = materialdata->shiness;
        const VECTOR3F& emissiveColor = materialdata->emissiveColor;

        const GLfloat amb[4] = {ambiantColor.x, ambiantColor.y, ambiantColor.z, 1.0f};
        const GLfloat diff[4] = {diffuseColor.x, diffuseColor.y, diffuseColor.z, 1.0f};
        const GLfloat spec[4] = {specularColor.x, specularColor.y, specularColor.z, 1.0f};
        const GLfloat emi[4] = {emissiveColor.x, emissiveColor.y, emissiveColor.z, 1.0f};

        glEnable(GL_COLOR_MATERIAL);

        glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, amb);
        glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, diff);
        glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, spec);
        glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, shiness);
        glMaterialfv(GL_FRONT_AND_BACK, GL_EMISSION, emi);
    }
    else
    {
        glDisable(GL_COLOR_MATERIAL);
    }
}

void RenderTexturedObject()
{
  FillVertexBuffer(mesh, t);
  FillTexCoordBuffer(mesh);
  FillColorBuffer(mesh, 255, 255, 255);

  glColor3ub(255, 255, 255);

  // Use normals only when lighting is used
  if (IsLightingEnabled() && s_nbLights > 0)
  {
    FillNormalBuffer(mesh, t);
    glEnableClientState(GL_NORMAL_ARRAY);
    glNormalPointer(GL_FLOAT, 12, gNormals);
  }

  glEnable(GL_TEXTURE_2D);
  glBindTexture(GL_TEXTURE_2D, tex);

  glEnableClientState(GL_VERTEX_ARRAY);
  glEnableClientState(GL_TEXTURE_COORD_ARRAY);
  glEnableClientState(GL_COLOR_ARRAY);

  glVertexPointer(3, GL_FLOAT, 0, gVertices);
  glTexCoordPointer(2, GL_FLOAT, 0, gTexCoords);
  glColorPointer(3, GL_UNSIGNED_BYTE, 0, gColors);
  glDrawElements(GL_TRIANGLES, 3 * mesh->nbtriangles, GL_UNSIGNED_SHORT, gIndexes);

  glDisable (GL_TEXTURE_2D);
  if (IsLightingEnabled() && s_nbLights > 0)
  {
    glDisableClientState(GL_NORMAL_ARRAY);
  }
}

void UseLights()
{
        for (int lightIdx = GL_LIGHT0; lightIdx <= GL_LIGHT7; lightIdx++)
        {
            const int idx = lightIdx - GL_LIGHT0;
            const LIGHT_DATA& lightdata = s_lightsData[idx];

            const VECTOR3F& ambiantColor = lightdata.ambiantColor;
            const VECTOR3F& diffuseColor = lightdata.diffuseColor;
            const VECTOR3F& specularColor = lightdata.specularColor;
            const VECTOR3F& direction = lightdata.direction;

            const GLfloat amb[4] = {ambiantColor.x, ambiantColor.y, ambiantColor.z, 1.0f};
            const GLfloat diff[4] = {diffuseColor.x, diffuseColor.y, diffuseColor.z, 1.0f};
            const GLfloat spec[4] = {specularColor.x, specularColor.y, specularColor.z, 1.0f};
            const GLfloat dir[4] = {-direction.x, -direction.y, -direction.z, 0.0f}; // always use w=0.0 for a direction

            glLightfv(lightIdx, GL_AMBIENT, amb);
            glLightfv(lightIdx, GL_DIFFUSE, diff);
            glLightfv(lightIdx, GL_SPECULAR, spec);
            glLightfv(lightIdx, GL_POSITION, dir);
            glLightf(lightIdx, GL_SPOT_EXPONENT, 0.0f);
            glLightf(lightIdx, GL_SPOT_CUTOFF, 180.0f);
        }

}

Answer 1

The solution is here : https://www.sjbaker.org/steve/omniv/opengl_lighting.html

2 things to do : I must to remove glEnable(GL_COLOR_MATERIAL);

I must also to set the global ambient with (1.0f,1.0f,1.0f,1.0f)