light bugs on 3D model

Question

I have this picture below that shows the 3D model and the light is not as I expected, I've already tried many ways but I can't figure out how to fix it. my normal vectors are fine

the goemetry:

        glGenVertexArrays(1, &VAOArray);
        glBindVertexArray(VAOArray);

        /* GENERATE THE BUFFERS */
        glGenBuffers(1, &bufferArray);

        /* SELECT THAT BUFFER TO WORK WITH */
        glBindBuffer(GL_ARRAY_BUFFER, bufferArray);
        glBufferData(GL_ARRAY_BUFFER, myMeshes.at(j).realPositions.size() * sizeof(float), (GLfloat*)RealPos, GL_STATIC_DRAW);
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
        glEnableVertexAttribArray(0);
glGenBuffers(1, &normalArray);
        glBindBuffer(GL_ARRAY_BUFFER, normalArray);
        glBufferData(GL_ARRAY_BUFFER, myMeshes.at(j).realNormals.size()*sizeof(float), (GLfloat*)RealNor, GL_STATIC_DRAW);
        glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, 0, 0);
        glEnableVertexAttribArray(3);

this is my code:

while (!glfwWindowShouldClose(window))
    {

        /* Render here */
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
        glm::mat4 view = glm::mat4(1.0f); 
        glm::mat4 projection = glm::mat4(1.0f);
        projection = glm::perspective(glm::radians(45.0f), (float)width / (float)heigh, 0.1f, 100.0f);

        view = glm::translate(view, glm::vec3(0.0f, 0.0f, transZ)); //this is for scroll mouse
        view = glm::translate(view, glm::vec3(0.0f, 0.0f, -2.0f));
        view = glm::translate(view, glm::vec3(0.0f, 0.0f, -5.0f));
                
        glUseProgram(programT);
        int lightColorLoc = glGetUniformLocation(programT, "lightColor");
        glUniformMatrix4fv(lightColorLoc, 1, GL_FALSE, glm::value_ptr(glm::vec3(1.0f, 0.0f, 0.0f)));

        int objectColorLoc = glGetUniformLocation(programT, "objectColor");
        glUniformMatrix4fv(objectColorLoc, 1, GL_FALSE, glm::value_ptr(glm::vec3(1.0f, 0.5f, 0.31f)));

        glm::vec3 lightPos(2.0f, 4.0f, 5.0f);
        int lightPosLoc = glGetUniformLocation(programT, "lightPos");
        glUniformMatrix4fv(lightPosLoc, 1, GL_FALSE, glm::value_ptr(lightPos));

        int projectionLocLight = glGetUniformLocation(programT, "projection");
            glUniformMatrix4fv(projectionLocLight, 1, GL_FALSE, glm::value_ptr(projection));
        glm::mat4 modelLight = glm::mat4(1.0f);
        int modelLocLight = glGetUniformLocation(programT, "model");
        glUniformMatrix4fv(modelLocLight, 1, GL_FALSE, glm::value_ptr(modelLight));

        glm::mat4 viewLight = glm::mat4(1.0f); 
        int viewLocLight = glGetUniformLocation(programT, "view");
        glUniformMatrix4fv(viewLocLight, 1, GL_FALSE, glm::value_ptr(viewLight));

        int viewLoc = glGetUniformLocation(programT, "view");
        glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));

        int projectionLoc = glGetUniformLocation(programT, "projection");
        glUniformMatrix4fv(projectionLoc, 1, GL_FALSE, glm::value_ptr(projection));

        model = glm::rotate(model, glm::radians(rotX), glm::vec3(1.0f, 0.0f, 0.0f));
        model = glm::rotate(model, glm::radians(rotY), glm::vec3(.0f, 1.0f, .0f));
        model = glm::rotate(model, glm::radians(rotZ), glm::vec3(.0f, 0.0f, 1.0f));
        int modelLoc = glGetUniformLocation(programT, "model");
        glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));

                 

        glGenerateMipmap(GL_TEXTURE_2D);
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, textureArray[0]);
        glUniform1i(glGetUniformLocation(programT, "ourTexture"), 0);
            


            glBindVertexArray(VAOArray[0]);
        glDrawArrays(GL_TRIANGLES, 0, myMeshes.at(0).Indices.size());
    

        
        /* Swap front and back buffers */
        glfwSwapBuffers(window);

        /* Poll for and process events */
        glfwPollEvents();
        glfwSetKeyCallback(window, key_callback);
        glfwSetScrollCallback(window, scroll_callback);
        glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
        
    }

vertex shader used for this project:

#version 330 core


layout (location = 0) in vec3 RealPos;
layout (location = 1) in vec3 vertex_color;
layout (location = 2) in vec2 vertex_textcoord;
layout (location = 3) in vec3 RealNor;


out vec3 vs_pos;
out vec3 vs_color;
out vec2 vs_text;
out vec3 normal;
out vec3 FragPos;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{
    vs_pos = RealPos;
    vs_color = vertex_color;
    vs_text=vertex_textcoord;
    
    FragPos = vec3(model * vec4(vs_pos, 1.0));
    mat3 normalMat = mat3(inverse(transpose(model)));
    normal = RealNor * normalMat;
    gl_Position = projection * view * model * vec4(vs_pos, 1.0);
}

fragment shader used:

#version 330 core

in vec2 vs_text;
in vec3 normal;

in vec3 FragPos;

uniform vec3 lightPos;
out vec4 gl_FragColor;



uniform vec3 objectColor;
uniform vec3 lightColor;


uniform sampler2D ourTexture;



void main()
{
    vec3 norm = normalize(normal);
    vec3 lightDir = normalize(lightPos - FragPos);
    float ambientStrength = 0.1;
    vec3 ambient = ambientStrength * lightColor;
    float diff = max(abs(dot(norm, lightDir)), 0.0);
    vec3 diffuse = diff * lightColor;
    vec3 result = (ambient + diffuse) * objectColor;
    gl_FragColor =  texture(ourTexture, vs_text) * diff;
}

can someone help me to fix this or maybe guide me to solve it?

thanks

The image can be explained if the normal vectors are wrong. The problem is not caused by the shader or the code, but by the mesh. The normal vectors of the mesh are wrong. — Rabbid76, Apr 07 '21 at 14:54

score 0 · Answer 1 · answered Apr 07 '21 at 09:20

0

It applies that matrix * vector == vector * (matrix)^T

You are calculating normals via normal = RealNor * normalMat;

This is not equal to normalMat * RealNor which results in wrong normals. So kommutate the expression to normalMat * RealNor and see if it fixes the issue.

answered Apr 07 '21 at 09:20

tnte

113
5

I changed it but now I got no dark side – Apr 07 '21 at 09:22
Remove the call of `abs` from diffuse coefficient calc. – tnte Apr 07 '21 at 09:27
then all the sides become dark – Apr 07 '21 at 09:32
Normals inverted for some reason? May try by multiply normals with - 1. – tnte Apr 07 '21 at 09:35
that's why I added ```abs``` – Apr 07 '21 at 09:37
But then your max function becomes irrelevant – tnte Apr 07 '21 at 09:39
how can I solve it ? – Apr 07 '21 at 09:42
1

Check if your normals are wrong directed by multiplying with -1, like `normal = -1 * (normalMat * RealNor)` and see if lighting is correct. if it is correct, make sure that your normals are pointing in the correct direction. this should be done during geometry definition client-side. – tnte Apr 07 '21 at 09:44
yes when I multiplied by -1, I have illuminated sides but not shadow when rotating the model – Apr 07 '21 at 09:46
Okay. I don't see any light calc issues in the shader right now, beside the things i told you. Maybe show your geometry definition. – tnte Apr 07 '21 at 09:49
I updated it, but I think it's okay for the geometry. I think something in my while loop? – Apr 07 '21 at 09:53
@Gamer *'"I think something in my while loop?"* - No nothing is wrong with your loop. The normal vectors are wrong. – Rabbid76 Apr 07 '21 at 14:58
@Gamer Multiply by -1 and remove `abs`. – Rabbid76 Apr 07 '21 at 19:06

light bugs on 3D model

1 Answers1