.. title: CG Class 9, Thurs 2019-09-19 .. slug: class09 .. date: 2019-09-19 .. tags: class .. category: .. link: .. description: .. type: text .. has_math: true .. sectnum:: .. contents:: Table of contents Today's iclicker questions -------------------------- #. What does this line do:: gl.bindBuffer( gl.ARRAY_BUFFER, vBuffer ); A. Create this buffer. #. Enable this buffer so that the shaders will use it. #. Get the address of variable vBuffer. #. Prevent this buffer from being modified. #. Specify that this buffer will be the object of future buffer operations. #. What does this line do:: var vBuffer = gl.createBuffer(); A. Create this buffer. #. Enable this buffer so that the shaders will use it. #. Get the address of variable vBuffer. #. Prevent this buffer from being modified. #. Specify that this buffer will be the object of future buffer operations. #. How does gl.drawArrays know when the vertices it's drawing in 3D? A. It's specified as one of the arguments in gl.drawArrays. #. It's specified as one of the arguments in gl.bufferData. #. It's specified as one of the arguments in gl.vertexAttribPointer. #. It's specified as one of the arguments in gl.getAttribLocation. #. It's specified as one of the arguments in gl.enableVertexAttribArray. #. How does gl.drawArrays know when the color values are floats instead of ints? A. It's specified as one of the arguments in gl.drawArrays. #. It's specified as one of the arguments in gl.bufferData. #. It's specified as one of the arguments in gl.vertexAttribPointer. #. It's specified as one of the arguments in gl.getAttribLocation. #. It's specified as one of the arguments in gl.enableVertexAttribArray. #. How does gl.drawArrays know how many triangles are in a triangle strip? A. It's specified as one of the arguments in gl.drawArrays. #. It's specified as one of the arguments in gl.bufferData. #. It's specified as one of the arguments in gl.vertexAttribPointer. #. It's specified as one of the arguments in gl.getAttribLocation. #. It's specified as one of the arguments in gl.enableVertexAttribArray. #. Normalize this vector: (8,-6,0). A. (3, 4, 5). #. (3/5, -4/5, 0). #. (4/5, -3/5, 0). #. (4/5, 3/5, 0). #. (8, -6, 10). #. Find a normal vector to the plane through the points (1,0,0), (1,1,0), (1,0,1). A. (0, -1, 0) #. (0, 1, 0) #. (1, 0, 0) #. (1, 1, 0) #. (3, 2, 2) #. Which of these curved surface equation types makes it easy to generate points on the surface? A. explicit #. explicit and implicit #. explicit and parametric #. implicit #. parametric #. Which of these curved surface equation types makes it easy to test whether a point is on the surface? A. explicit #. explicit and implicit #. explicit and parametric #. implicit #. parametric #. What type of equation is this: :math:`x^2+y^2+z^2=1` A. explicit #. explicit and implicit #. explicit and parametric #. implicit #. parametric Homogeneous coordinates ----------------------- `My take on homogeneous coordinates `_. IMNSHO (In My Not So Humble Opinion) it's better than the book. Textbook slides: Chapter 5 -------------------------- The big topic for Chapter 5 is homogeneous coordinates. They allow all the common transformations - translation, rotation, scaling, projection - to be expressed as a multiplication by a 4x4 matrix. #. `5_1 Representation `_ - I'll do this really quickly. Textbook programs ----------------------- `My local web copy `_ . `My copy on RCS `_. #. Chapter 4: #. color interpolation #. element arrays #. etc We'll skip quaternions until we see 3D rotations. SIGGRAPH 2017 videos --------------------- SIGGRAPH is the world's leading CG conference. I'll show various videos from it. #. SIGGRAPH 2017 `Computer Animation Festival Trailer `_. #. `SIGGRAPH 2017 VR Village Trailer `_. #. `The Sketchy Database: Learning to Retrieve Badly Drawn Bunnies - SIGGRAPH 2016 `_. #. `Samsung Official Ostrich Commercial || Gear VR Advertisement `_. Nice WebGL site --------------- http://webglfundamentals.org/webgl/lessons/