Control Task (Shading and Lighting)

Assignment presentation

• Prepare a 2 min video presenting your software;
• Share the link to your GIThub repo through this form;
• The practical assignment has to reside in a branch named ControlTask.

Requirements

    Use sources from PA#1 adding a new functionality as follows:

• Render the surface with filled triangles using VBO (Vertex Buffer Object) technology with indices;
• Add two sliders providing ability to control surface granularity over U and V directions;
• Implement triangle shading method as per variant;
• Implement vertex and pixel shaders that calculate intensity of illumination for the surface coming from a single light source: I_rgb=Ambient+Diffuse+Specular that rotates in a circle motion around the surface. 

Resources

    The project we started to code at the lecture is here WebGL (branch PA2)

Details on Normals Calculation

• Facet Average normal: sum all facet normals that are adjacent to the vertex to form a vertex normal, normalize the result;
• Facet Weighted Average normal: sum all facet normals that are adjacent to the vertex to form a vertex normal observing weight, normalize the result;
• pass the vertex normals as vertex attributes to GPU.

Details on Gouraud/Phong shading

    Implement the necessary code in .js and/or vertex/fragment shader.

Details on a Local light source

• pass coordinates of a light source to GPU as uniform parameter;
• do not forget to multiply the coordinates by ModelView matrix before passing them to GPU.

Details on projection

    use single point perspective/orthographic matrix.

Hint

• when calculating specular component you can take (0,0,1) direction vector as the vector pointing towards the viewer instead of calculating per-pixel direction (global viewer model);
• intensity of the light source components can be hardcoded in the shader;
• you can calculate the world coordinates of each point in fragment shader  interpolating vertex coordinates using hardware interpolator (varying keyword);
• If you need to interpolate normals along primitive pass them to fragment shader using varying keyword.

Variants

• Chagovets O. Shading model Gouraud, Facet Average Normal
• Kandaurov S. Shading model Phong, weighted Facet Average Normal