Mtg 17/23: Wed-13-Nov-2024

Outline for Today

Texture Mapping

Administration

Today

midterm exam grades posted and the marked exams will be available on gradescope later today (you will receive an email)
Assignment 2 marks posted
Assignments 3 and 4 now available on UR Courses
2 opportunities to give me feedback are open until 23:59 today
Chapter 7 code samples

For Next Meeting

Submit your response to this meeting before noon tomorrow
Read the rest of Chapter 7
Take the quiz before the start of our next meeting

Wiki

Link to the UR Courses wiki page for this meeting

Media

Transcript

Audio Transcript

That good. Hey, I
I didn't charge over the weekend,
so I'll see what that will help to plug in. I'll just stand
right here for the whole time I
may then get a few minutes worth of charge.
So have you found your midterm marks online? I
so I've adjusted them
so it's out of 15, so the lowest marks are between 7.5 and 15.
Does that make sense?
So what you'll get from grade scope will be a mark out of 77
and
I've done some adjustment from the grade, from the exam and
grade scope to your courses, acknowledging the fact that it
may have been a bit long. Who agrees with that statement? It
was too long.
Yeah. Well,
so I want everyone to not I don't want anyone to be
discouraged by the exam, but it's it's meant to be formative
feedback for You, and if you do better on the
final I will wave the final more heavily towards Your final
grade.
Any questions or concerns about that I
so also Simon
two has been created and marks release, and
I have assignments three and four posted as well. So the idea
is you'll build on the code from assignment Two. We'll talk about
that In just a second. I
so a reminder that there are two opportunities for feedback
to me about the mentoring plan and about me
that are going to close at midnight, one minute to midnight
tonight. So if you want to give your input, that would be much
appreciated. The one about the midterm exam, I'll count out
words of participation so it's not the feedback is anonymous,
But the forward evaluation of the class is anonymous.
Okay?
And thanks to the people who pointed out I had not had last
week's dates on the quiz,
so I hope everyone had A chance to complete it.
Okay, let's see whether I have enough battery
to last.
Oh, it says less than an hour. So,
okay, so,
based on the midterm I was, I've been thinking about assignments,
so I want to focus on the things that we've been doing.
So fly by this will give you some practice With specifying
camera coordinates and
so I'm asking for
A two things in terms of Flying Wild, smoking And
I will make,
I will prepare a version of assignment two code for
for those who have a chance To do
assignment reviews,
they've Got a starting point for
so fly by in two ways.
One, all the line, so
let's say we have
Looking at the plot of our assignment two and
this is the one that's a lid that opens,
but we might have
some other objects the
then we can specify a line.
Let's add
a reasonable height so We don't
hit The boxes and
so you
might say, here's The camera, and let's look at just a little
bit ahead of us, or
maybe look at 45 degrees
in front of us. Then as we step along the line, we're changing
the lookout point
so we'll see this
box first, And then this one and Then the Third One. The
Okay, does that make sense? So the look at point, it's fixed in
relation to the eye point. And as we move along the line,
removing the eye point, so that the look at point,
you can feel kind of imagine the piece of chalk pointing to The
place where we're looking.
Does that make sense? Do
This is the first way,
second way travel along. I
kind of along A circular, circular spiral and
so this time,
We're going to always look at the middle and
So we start out at
a point here and
and all the time we're looking at the middle.
So maybe that's enough. So do two rotations,
and at the starting point,
just a different height.
Does that make sense?
So it should spiral upwards,
not outwards. But should you be moving further away, like as
you're rotating around or just moving up? I
I was thinking of just moving up or down if you want to have an
option To fly closer, further away. You can do that. You
So that's assignment three and
so For fly by option one,
move The leg with The camera and
so the length can be stationary when we're going In the spiral.
So I do
I use the Same material and
same material For the whole scene And
so does that make sense? What I'm asking?
Okay,
so I think we can be flexible on the due dates.
I've said Monday the 25th for the for assignment Three and
Friday, December 6 for assignment four. You
I would say Friday, December 6. We don't want to make it later
than that. But if you wanted some flexibility to submit
assignment three later or closer to December 6, that would be
fine. Does that make sense? Does that seem like a good idea?
So I don't want to discourage you from the I'm submitting
assignment three on the 25th
but if you need some flexibility, I think we can
provide it. Does that seem okay? I
Okay, I
so let's take a look At the shaded cube.
Example,
chapter six and
so just
so Let's look at the shaders first and
so we have in we get the position of the vertices through
a position which we're connecting to our buffer in the
JavaScript,
then we're also getting a normal vector, not a single normal
vector, but a vertex attribute. So we get normal associated with
the vertex and then we have a vertex color that's passed on to
the fragment shader. So then we have uniform variables. So we
have the ambient product, the diffuse product and the specular
product. So these are the different contributions in our
lighting model. So ambient is just background light.
Diffuse
is the
light that gets scattered,
in general, and then the specular is when we're dealing
with a shiny surface, and we're close to the reflected ray of
the light, then we'll see a specular highlight.
So we have those terms to
configure into our computation, then we have the wall view
Matrix, projection matrix, light position and a shininess
coefficient and
B, so we compute the position,
so we get X, Y and Z of the position. That's what this
operator does at the end here, and we're changing the sign.
Then we get our fixed light position
that comes from the uniform of the JavaScript.
So we get
a vector l, which we normalize, is a difference between the
light and position, and
the i
vector is normalized minus pause and H, the half wave vector, The
half vector.
So we normalize L plus E.
Then
we take
the normal X, Y, Z,
and we add
a zero for w, and it's zero because It's a vector.
So we transform normal n of two I coordinates and
we compute our
illumination equation. We have ambient
and the diffuse and specular and
so we're testing here.
If the angle is greater than 90, we're not going to have
a color for specular.
Then the position
we take our vertex attribute multiply by our wall of V
matrix, then our projection matrix and our V color becomes
sum of ambient, diffuse and specular, and then we set so
that's three terms, and the Alpha we set to one. So that's
doing
the modified
the blin Fong using the
blin Fong model,
and then in the fragment shader, we're just passing through the
vertex color to the fragment color.
So we're getting the computation at the vertices with the
normals, and then we're interpolating the intensity
across,
in to the Vertice, to the fragments between the vertices.
We're just interpolating the intensities so we're not we're
we're not recomputing the lighting for every fragment.
So what
kind of shading is This?
No, it's not flat. I
There are two kinds,
anyone like a vowel or whatever It's called,
yes,
grow
and who's the other one? I've mentioned him already.
Yeah,
so in the row we're calculating, doing the calculation the
vertices and then interpolating the intensities of Quang
shading. We're interpolating the vector so we have, we can do the
full computation for each fragment. For
we're still doing an approximation to the normals,
but we it's a better approximation than we're Getting
with the Grow shading. Does that make sense? I
so we in our JavaScript, we have vertices for the cue, plate,
position, ambient, diffuse, specular, light parameters and
then we have the material specified in terms of ambient,
diffuse, specular and China's and
so we're computing the normal vectors For the triangles here,
so we get t1 is t,
is vertex B
and A and
vertex C and B And
anyway, he has strange ways of organizing parameters. Sometimes
these function calls, so we get two vectors based on the edges
of the triangle, and then the normal vector is the cross
product. We
so we push
the normal to our normal brain And so
he's assigning the same normal to the squad. So it's making the
assumption that it's flat, which may not be the case.
So we get the color cube.
So here's the new stuff with
the normal array.
Here we're doing three bytes or three values per normal vector.
We're
so we're doing the multiplication. Take the ambient
light, and we multiply it by the materials, ambient properties,
and the diffuse product is the diffuse light times the material
property diffuse properties of the material and the specular
product is the specular specular light times the specular
properties of the material.
Then we set the ambient, we set uniforms. We need a key here,
and
we flatten the matrix
pass associated with The projection matrix uniform in the
vertex shader, and we're
and we're changing the model V matrix based on The rotation
that we set. Does
that make sense? I
I wanted To
tell COVID.
So I thought maybe we could start by looking at some code
samples from chapter seven. I
so what is the purpose of texture mapping? Let's start
with that Question. I
any thoughts i
What if you want to capture
the details,
the feeling of a chalkboard that has that's been written on a Few
times and erased The
so we might take a picture, a picture of the board
that captures the
swirls of the eraser,
and We might map that on
to
polygon
for our small
that's going to represent the blackboard In our ball.
So we may do environment Mapping. I
So An environment man, I it
has anyone seen Terminator two? That was when the
first exam was on, because the robot
was sent to kill a Schwarzenegger. This robot,
there's a new version who can become liquid metal. So that's a
shiny blob. So then the details of the environment are visible
in that computer generated object.
So there is
a sense that we have involved
the environment that gets
mapped on to the the surface of the object. And then there's
also what's happening. And
so the idea is we can add complexity to
a smooth, polygonal surface
if we perturb the normal vectors and
is so instead of the normal vector being normal, we can
change the direction of the normal vectors and thereby
create the impression of a more complex surface and the idea is
that we're going to Get more complexity in the image in
inexpensive ways. And
so here's a Simple bump Mapping
example. I
so
we're creating a texture,
256, So then we have the bump data to
it's basically creating a
two by two array, 256 by 256, of zeros and ones that correspond
to that shape.
If you can see the Can you see the inset
square?
So then we set the normals based on the data.
Then we have the idea of texture coordinates, which is going to
describe
how to
map the texture that we have the image that we want to paste onto
the model. How the texture gets mapped on to the surface. I
so we configure the texture, we pass the image, create a
texture, and we're
going to say it's active, the texture zero is active, and
we're going to make a texture imaged. So for the
mesh, we're putting the vertices as well as the texture
coordinates and
so here We have a texture coordinates array and we
have an attribute variable in the sheet that's connected to
the shader for The texture coordinates.
Then we have all the same uniform set up and
so the Configure texture normals, So we're passing
normals, and
we Set up here.
U n8
array and
so what is that? What is the effect of this?
So you end
eight array is an array of unsigned integers. So
eight bits,
256, values, 255, character.
So yeah,
I don't know that they have
unsigned character. I
Yeah, it's one byte, eight bits. So we're allocating three bytes
for each point in the texture. So it's
we're creating, we're going to pass the normals
into
the Configure and
so the parameter in for the function configure
texture is an image.
So this is a line where we're converting the image into a
texture and
the generated bitmap. That's idea of having different
resolutions of the texture.
So we can choose the one that's more most appropriate for the
application. Let's go ahead
and see what
can you See The Light moving A little bit? I
me. So we had the impression of death because of the way that
the way that set up. So now, if we
change the light position, you
so first blush, that doesn't seem like a flat
surface, doesn't I
so here we're loading an image.
We're pasting it on to the queue. Let's
Take a quick look at this code. Hello.
So here we're passing.
So we're taking input of
the bay position,
which is x, y, z and w,
a color, which is RGBA, and text coordinate, which is s and t.
So it's two dimensional. The image is 2d so we're just
specifying coordinates and the image to
cube.
So you're doing rotation and we're saying texture coordinates
based on but we're doing a similar pass through we're doing
we're assigning
V color, the value of a color and assigning V tech quart,
value of A tech quart.
So then we have input
of the vertex color
and the texture coordinate,
then we have a sampler that
makes association between the texture map and the texture
coordinate,
so the fragrance color is texture is accessing the
texture, universal texture, uniform, texture map, texture
coordinate. Does that make sense? You?
Set up the image and
so here's Some of the image is loaded from H to ml so
right? So that's where the image is located. The
so when we're initializing or configuring the texture with the
image. Then the last line is the
tech texture map,
mutex map we're looking to our shading To
it seems to be a typo. Here
you text you tech map. Here you text your map in the
code, in the HTML, you
so I suspect it's doing some good defaults. I'll check on
that.
Report back.
Okay, we're out of time today. Any questions or concerns before
we say goodbye? I
it? No, I'm gonna, I just have to draft an email so it'll be
sent shortly. I
Okay, thank you for today. Have a great Wednesday and a good
weekend, and I'll see you on Monday.

Responses

What important concept or perspective did you encounter today?

Digital image representation seemed like an important topic
Today I learned about the importance of texture mapping. It allows for cool abd realistic effects when line shines on an object.
Different types of mapping to make the surface look more comlex than it actually is. Types we encountred were bump, texture, and environement mapping.
Texture mapping!
Assignment3,4 and Gouraud and phone Shading and Texture Mapping
Bump mapping essentially is perturbing the normal vector of a surface to be rendered
More samplw codes for textures
The concept of texture mapping provides a way to add rich surface details to 3D objects, achieving a sense of complexity that would be difficult to model directly. Environment mapping captures surrounding environmental details to simulate reflections, while bump mapping adds perceived depth and texture to surfaces.
learn assignment 3, 4 and bump mapping
the type of shading, flat, Gouraud shading and phong shading

Was there anything today that was difficult to understand?

Was there anything today about which you would like to know more?

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