glulookat

Compatibility function for gluLookAt

由 跟風遠走 提交于 2021-02-11 07:53:08
问题 I just got a new PC and now have to get my demo program running with SDL2/OpenGL. I used the program to try out various techniques and used gluLookAt (which, obviously, shouldn't be used any more or even never should have been used). Now I'm looking for a way to replace the gluLookAt method by building a transformation matrix doing the same as gluLookAt did. I came across this claiming to be usable replacement for gluLookAt (the answer - not the question). My implementation of it looks like

OpenGL 3 (LWJGL) LookAt Matrix Confusion

由 拥有回忆 提交于 2020-01-10 19:40:11
问题 I'm learning OpenGL 3 using LWJGL. I have tried to implement an equivalent to gluLookAt() , and although it works am I somewhat confused as to why. I confess to just copying this code from various sources on the web, but after much study I think understand the maths behind it, and that I understand what LWJGL is doing. However the 'correct' gluLookAt code behaved incorrectly in my application, as the camera seemed to be turning the wrong way. I only managed to get my code working by

LookAt Implementation Misbehaviors

由 天大地大妈咪最大 提交于 2020-01-05 04:33:08
问题 I'm looking forward to implement a LookAt( forward, up ) method where: Vector3 forward = eyePosition - targetPosition; Vector3 up; I've seen some implementations over the web, but analizing the code, I've found potencial misbehaviors... I list them from easiest to hardest: 1) This won't work if UP is a zero vector. 2) This won't work if FORWARD is a zero vector. 3) This won't work if UP and FORWARD are parallels. ... So.. How should this method correctly be implemented? Here is a code example

The LookAt target location doesn't matter if it is z = 0 or z = 1000 or -1000?

由 旧街凉风 提交于 2019-12-24 07:59:34
问题 I am trying LookAt in OpenGL ES, gluLookAt(512, 384, 2000, 512, 384, 0, 0.0f, 1.0f, 0.0f); The second row is the Target's position... so I wonder, if I change the z from 0 to 1000 or -1000 , shouldn't what is seen different? They turn out to be all the same, why is that? 回答1: From the OpenGL spec for gluLookAt, it states the inputs as: gluLookAt(GLdouble eyeX , GLdouble eyeY , GLdouble eyeZ , GLdouble centerX , GLdouble centerY , GLdouble centerZ , GLdouble upX , GLdouble upY , GLdouble upZ )

gluLookAt() best usage, on GL_PROJECTION matrix or on GL_MODELVIEW matrix

由 这一生的挚爱 提交于 2019-12-10 03:19:13
问题 The OpenGL documentation say that the gluLookAt() calls should be done on the GL_MODELVIEW matrix: http://www.opengl.org/resources/faq/technical/viewing.htm In fact the docs link to an article which say that using gluLookAt() on the GL_PROJECTION matrix is extremly bad: Help stamp out GL_PROJECTION abuse On the other hand, there are a lot of tutorials and examples where gluLookAt() is in fact called on the GL_PROJECTION matrix. And at the same time, while the article mentioned above does say

How does gluLookAt work?

由 妖精的绣舞 提交于 2019-12-06 02:45:50
问题 From my understanding, gluLookAt( eye_x, eye_y, eye_z, center_x, center_y, center_z, up_x, up_y, up_z ); is equivalent to: glRotatef(B, 0.0, 0.0, 1.0); glRotatef(A, wx, wy, wz); glTranslatef(-eye_x, -eye_y, -eye_z); But when I print out the ModelView matrix, the call to glTranslatef() doesn't seem to work properly. Here is the code snippet: #include <stdlib.h> #include <stdio.h> #include <GL/glut.h> #include <iomanip> #include <iostream> #include <string> using namespace std; static const int

gluLookAt() best usage, on GL_PROJECTION matrix or on GL_MODELVIEW matrix

由 风格不统一 提交于 2019-12-05 03:59:20
The OpenGL documentation say that the gluLookAt() calls should be done on the GL_MODELVIEW matrix: http://www.opengl.org/resources/faq/technical/viewing.htm In fact the docs link to an article which say that using gluLookAt() on the GL_PROJECTION matrix is extremly bad: Help stamp out GL_PROJECTION abuse On the other hand, there are a lot of tutorials and examples where gluLookAt() is in fact called on the GL_PROJECTION matrix. And at the same time, while the article mentioned above does say to NOT use it on the GL_PROJECTION matrix, it sais that in most such usages there's no visible problem

LookAt function: I'm going crazy

由 我怕爱的太早我们不能终老 提交于 2019-12-04 00:55:49
问题 I must do a homework and I try to implement a lookAt function. I tried in many ways but the only result I got is a blue screen. The rest of my program works greatly, infact if I use glm::lookAt all is good. This is my code: mat4 Transform::lookAt(const vec3 &eye, const vec3 &center, const vec3 &up) { vec3 w(glm::normalize(eye - center)) ; vec3 u(glm::normalize(glm::cross(up, w))); vec3 v(glm::cross(w, u)) ; mat4 ret = mat4 ( vec4 (u.x,v.x,w.x,0), vec4 (u.y,v.y,w.y,0), vec4 (u.z,v.z,w.z,0),

LookAt function: I'm going crazy

由 时光毁灭记忆、已成空白 提交于 2019-12-01 03:44:43
I must do a homework and I try to implement a lookAt function. I tried in many ways but the only result I got is a blue screen. The rest of my program works greatly, infact if I use glm::lookAt all is good. This is my code: mat4 Transform::lookAt(const vec3 &eye, const vec3 &center, const vec3 &up) { vec3 w(glm::normalize(eye - center)) ; vec3 u(glm::normalize(glm::cross(up, w))); vec3 v(glm::cross(w, u)) ; mat4 ret = mat4 ( vec4 (u.x,v.x,w.x,0), vec4 (u.y,v.y,w.y,0), vec4 (u.z,v.z,w.z,0), vec4 (-u.x*eye.x-u.y*eye.y-u.z*eye.z, -v.x*eye.x-v.y*eye.y-v.z*eye.z, -w.x*eye.x-w.y*eye.y-w.z*eye.z, 1)

gluPerspective, glViewport, gluLookAt and the GL_PROJECTION and GL_MODELVIEW Matricies

由 此生再无相见时 提交于 2019-11-28 20:54:10
Original Question I want to use 'gluPerspective', 'glViewport' and 'gluLookAt' to manipulate my camera and screen. Which functions to I apply to which matrix mode? And in what order should I / must I use them? For example, I am trying to set up my screen and camera like this: (But it is not working!) glMatrixMode(GL_PROJECTION) // Apply following to projection matrix - is this correct? glLoadIdentity(); // Reset first glPerspective(45.0, (double)w/(double)h, 1.0, 200.0); // Set perspective glViewport(0, 0, w, h); // Set viewport glMatrixMode(GL_MODELVIEW); // Apply following to modelview -
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