3D Objects

Overview

3D Objects is a Qt 6 desktop application that integrates OpenGL 4.5 Core Profile into a Qt Widgets interface.
It renders a 3D scene consisting of a flat ground plane and any number of user‑imported 3D models.
Models are loaded at runtime from OBJ files using the Assimp library, so you can drop arbitrary meshes into the scene without recompiling.
Each imported mesh gets its own VAO/VBO and can be individually selected, transformed, and recolored.

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Features

• Modern OpenGL 4.5 Core Profile (no deprecated functions)
• Dynamic loading of OBJ files using Assimp
• Flat ground plane as a base for all models
• Camera controls:
  • Orbit, pan, and dolly with mouse and keyboard
• Per-object manipulation:
  • Select, translate (drag), and scale individual objects
• Independent VAO/VBO per object
• Coloring modes based on vertex attributes:
  • Uniform color
  • Position (world space)
  • Normal direction
  • UV coordinates
• GLSL 4.50 shaders using in/out varyings and uniforms
• Built using CMake, GLM, Qt 6, and Assimp

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Prerequisites

Dependency	Minimum Version	Purpose
Qt 6	6.5+	Core / GUI / Widgets / OpenGL
CMake	3.21+	Build system
GLM	Latest	Matrix and vector math
Assimp	5.3+	Import OBJ models
C++ Compiler	C++20/C++23	MSVC, MinGW, Clang, or GCC

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How It Works

Object Loading

• Press Object to import an OBJ file.
• Geometry is loaded via Assimp and centered above the ground.
• Each object gets its own VAO/VBO and is rendered independently.

Ground

• Rendered by scaling a unit cube.
• Positioned at y = -2.0 and sized to cover a large flat area.

Object Transformations

• Select an object by double-clicking.
• Drag to move it along the ground.
• Use the mouse wheel to scale.
• Only one object can be selected at a time.

Coloring Modes

• Use the dropdown to choose:
  • Uniform
  • Position
  • Normal
  • UV
  • Position + Normal
• Colors are blended with a base tint per object.

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Controls

Mouse

Action	Effect
Left-drag	Orbit scene (or deselect object)
Middle-drag	Orbit scene
Right-drag	Pan camera or drag selected object
Shift + Right-drag	Move vertically
Mouse wheel	Dolly or scale selected object
Double-click	Select object

Keyboard

Keys	Action
W / S	Move camera forward/back
A / D	Move camera left/right
R / F	Move camera up/down
I / K	Pitch camera up/down
J / L	Yaw camera left/right
U / O	Roll camera
Backspace	Delete selected object

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Project Structure

3D-objects/
├─ CMakeLists.txt
├─ main.cpp
├─ main_window.(h|cpp|ui)
├─ view_3D.(h|cpp)
├─ shaders/
└─ resources.qrc

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Shader Pipeline (GLSL 4.50)

Vertex Shader

#version 450 core
layout(location = 0) in vec3 position;
layout(location = 1) in vec3 normal;
layout(location = 2) in vec2 texcoord;
uniform mat4 mvp;
uniform mat4 model;
uniform mat3 normal_matrix;
out vec3 vWorldPosition;
out vec3 vNormal;
out vec2 vTexCoord;

void main() {
    gl_Position = mvp * vec4(position, 1.0);
    vWorldPosition = vec3(model * vec4(position, 1.0));
    vNormal = normalize(normal_matrix * normal);
    vTexCoord = texcoord;
}

Fragment Shader

#version 450 core
in vec3 vWorldPosition;
in vec3 vNormal;
in vec2 vTexCoord;
uniform int color_mode;
uniform vec4 color;
out vec4 FragColor;

void main() {
    vec4 final_color = color;

    if (color_mode == 1) {
        final_color.rgb = normalize(vWorldPosition) * 0.5 + 0.5;
    } else if (color_mode == 2) {
        final_color.rgb = normalize(vNormal) * 0.5 + 0.5;
    } else if (color_mode == 3) {
        final_color.rgb = vec3(fract(vTexCoord), 0.5);
    }

    FragColor = mix(final_color, color, 0.35);
}

Notes

• A small height offset avoids z-fighting between objects and the ground.
• Right-click on empty space to deselect.