Computer Graphics Stack Exchange
Computer Graphics Stack Exchange

Questions tagged [glm]

16 questions
21
votes
1 answer

Get vector length with GLM

I am quite confused over how GLM library is behaving or I am using it improperly. glm::vec2 testVec(6,-4); float len = testVec.length(); I get the value 2 with the above code snippet. I believe I am trying to get the length of the vector defined…
sajis997
  • 1,209
  • 1
  • 9
  • 13
11
votes
4 answers

Multiple viewports with modern OpenGL?

I use SDL2. Currently my only shader has a MVP matrix, and transforms the points with it. I calculate my View and Projection matrix for a camera with GLM: glm::lookAt(pos, pos + forward, up); glm::perspective(fov, aspectRatio, zNear, zFar); I…
Tudvari
  • 313
  • 1
  • 2
  • 13
4
votes
1 answer

Three quaternions interpolation with barycentric coordinates

I have three quaternions A, B, C. I also have a 3D vector P which describes the barycentric coordinate to interpolate. I want to interpolate the three quaternions with respect to the barycentric coordinate P This Image shows how to do it would A, B…
Thomas
  • 631
  • 1
  • 3
  • 11
4
votes
1 answer

understanding glm::perspective vs glm::ortho

I'm new to computer graphics. I played around with OpenGL and now am trying out Vulkan. Basically what I want to do, in 2D is have an 800x800 window, and I want that to represent 800 meters by 800 meters. Then I want a circle with a radius of 1…
mikeglaz
  • 259
  • 4
  • 6
3
votes
1 answer

Screen to World coordinates glm::unProject

I'm having some trouble trying to figure out how to go from a coordinate on the screen, to 3D world coordinates on a plane. My case is as seen on the picture further down. World origin is in the center with the grid representing the X-Y plane. I…
remi000
  • 230
  • 3
  • 8
3
votes
1 answer

Ray-tracing the Cornell Box results in really inconsistent image

So I have a vector of glm::vec3 containing the triangles for the classic Cornell Box called triangles. The Draw method casts a ray for each pixel on the screen and calls ClosestIntersection which returns true or false and updates a struct containing…
swedish_fisk
  • 33
  • 2
2
votes
0 answers

What is the projection matrix of reverse (Byzantine) perspective?

I would like to construct a projection matrix for reverse perspective. I'm using OpenGL and tried to modify concepts from this excelent tutorial. I came up with: $$ \begin{bmatrix} 2\frac{(near-M)}{right-left} & 0 & \frac{right + left}{right-left}…
Peter
  • 21
  • 1
2
votes
0 answers

With OpenGL, is it correct to apply model transformation to rotate the camera?

Having taken a basic CG course, I remember that transformations are relative, so rotating the camera is identical to rotating the view in the opposite direction. Right now I want to implement camera rotation using the mouse. In OpenGL, I can see the…
iksemyonov
  • 121
  • 2
1
vote
0 answers

360 degrees rotation around x axis

How do we rotate the camera around x axis 360 degrees, without having to flip the axis, meaning without having the strange flip after we go over +-90 degrees on x axis. Mine behaves exactly the same way spherical coordinates would, I'm using euler…
Test
  • 31
  • 2
1
vote
1 answer

My (ADS) shader doesn't render the light direction correctly

This is what I'm doing: vertex shader: #version 400 layout ( location = 0 ) in vec3 vertex_position; layout ( location = 1 ) in vec3 vertex_normal; uniform mat4 ModelViewMatrix; //view*model uniform mat3 NormalMatrix;…
Charlie
  • 203
  • 1
  • 7
1
vote
1 answer

Am I passing the correct matrices for my shader? openGL/C++

On page 89 of David Wolff - OpenGL 4.0 Shading Language Cookbook book, it suggests a way to set up up a Phong shader in the fragment stage. It lists some different matrices to pass via uniform, and I suspect I might be passing slightly incorrect…
Charlie
  • 203
  • 1
  • 7
1
vote
1 answer

Converting points, vectors, normals between world and object space for a ray tracer gives weird results

I'm writing a ray tracer but having trouble converting rays and normals between world space and object space. I am creating a Ray, then transforming it with transformation matrices, calculating intersections and return them. Constructing…
Cedric
  • 13
  • 2
0
votes
1 answer

Wrong reflection

Here is a youtube video showing my problem: youtube.com/watch?v=y8J7VhS2pkM I think I'm either doing the texture lookup on the reflection texture wrong, or the reflection or view matrix is somehow wrong. The reflection matrix is calculated after…
Martin Gerhardy
  • 101
  • 1
0
votes
0 answers

How to rotate an object in OpenGL on the X, Y and Z axis on its local coordinates?

I've read multiple tutorials, but I still can't understand how do I properly rotate an object in 3D space on all 3 axis at once. For example, I'd like to give the object a pitch of 60 degrees, yaw of 20 degrees and roll of 70 degrees. How can I…
John
  • 101
  • 2
-1
votes
2 answers

How can i wrap the earth image around a 3D Sphere using OpenGL, GLFW, GLAD, GLM?

Please help me out with this thing and currently i am a little more than a beginner so please tell me in that context. i don't need any obsolete methods for creating this like using GLUT or GLEW.can you just tell me its algorithm to create the…
b_cass_
  • 25
  • 5
1
2