This program loads an OBJ file of a 3D model and allows the user to translate, rotate and scale the model. In addition, the shader used to render the object can be changed during runtime.
Here is a list of the shaders that are currently included in this program.
- Skeleton Shader
- Wireframe Shader
- Gouraud Shader
- Blinn-Phong Shader
- Texture Mapped Shader
- Normal Mapped Shader
- Checkerboard Shader
- Cross-hatching Shader
- Cel Shader
- Gooch Shader
To run the program, run the following command from inside the project directory (or you can use ant run).
$ ant
You can use the following keys to manipulate the mesh.
| Key | Action |
|---|---|
| Q | Select next GameObject |
| W | Select previous GameObject |
| E | Scale current GameObject up |
| R | Scale current GameObject down |
| T | Translate current GameObject right |
| Y | Translate current GameObject left |
| U | Translate current GameObject up |
| I | Translate current GameObject down |
| O | Translate current GameObject forward |
| P | Translate current GameObject backward |
| A | Rotate current GameObject positively about the x-axis |
| S | Rotate current GameObject negatively about the x-axis |
| D | Rotate current GameObject positively about the y-axis |
| F | Rotate current GameObject negatively about the y-axis |
| G | Rotate current GameObject positively about the z-axis |
| H | Rotate current GameObject negatively about the z-axis |
| Space | Toggle through the shaders |
| 0 | Translate the current GameObject's mesh |
| 1 | Take a screenshot |
| 3 | Enable the first shader |
| 4 | Enable the second shader |
| 5 | Enable the third shader |
| 7 | Reflect the current GameObject's mesh |
| 8 | Scale the current GameObject's mesh |
| 9 | Rotate the current GameObject's mesh |
A simple, flat shader that adds a reddish-tint uniformly to the mesh and only takes into consideration ambient lighting.
Renders the wireframe of the object--edges of each triangle in the mesh are highlighted in white, while all other faces black.
This shader was done by assigning barycentric coordinates in the geometry shader to each vertex of the triangle primitive. Then the fragment shader assigns a color (black / white) based on the barycentric coordinate.
See detailed information here.
Ambient, diffuse and specular lighting are computed per vertex in the vertex shader. This leads to more artifacting and gives objects a faceted look due to linear interpolation of lighting intensity throughout each triangle primitive.
See Wikipedia entry here for more details.
Similar to the Gouraud Shader, the Blinn-Phong shader computes ambient, diffuse and specular lighting. However, this computation occurs per fragment in the fragment shader, which fixes the artifacts seen in the Gouraud shader.
Renders a Minecraft grass block.
Given a texture and a cube model with appropriate UV texture mapping, the RGB values from the texture can trivially be applied to the model to generate this Minecraft block.
Renders a cube with a brick texture.
Rather than using the RGB values from the texture, the normals of each fragment can be modified using a normal map. Here is an article that clearly explains this.
Procedurally-generated a checkerboard pattern using the model's texture coordinates and applied it to the mesh.
Hatching is an drawing technique that is fully explained here.
Using this resource, it is quite simple to create a shader that gives each mesh a Hatching-esque appearance.
Cel shading (or Toon shading) is covered in this Wikipedia entry.
This shading technique makes objects look cartoon-like and is used in games like Ookami and The Legend of Zelda: Breath of the Wild.
Gooch shading is a non-photorealistic rendering method developed by Amy Gooch at the University of Utah. More information about the shader can be found here.
Object fragments whose normals point away from the light source receive a cool color shading, while fragments whose normals point in the same direction as the light source receive a warm color shading.
Note: I used this resource for creating the Gooch shader.
- For wireframe: http://codeflow.org/entries/2012/aug/02/easy-wireframe-display-with-barycentric-coordinates/
- For normal mapping: https://learnopengl.com/Advanced-Lighting/Normal-Mapping
- For cel shading: http://www.lighthouse3d.com/tutorials/glsl-12-tutorial/toon-shader-version-ii/
- For hatching and gooch: https://www.eecs.yorku.ca/course_archive/2011-12/W/4431/lectures/Day20.pptx