I'm drawing a bunch of points inside a 64x64x64 cube and can't figure out how to displace the origin so that rotations are done around the center of the cube.
My vertex data is stored inside a 1D array, going from {(0,0,0), (0,0,1), ..., (63, 63, 63)}.
This is my current code to setup the matrices each frame:
// Set ProjectionMatrix
projectionMatrix = glm::perspective(90.0f, (GLfloat)width / (GLfloat) height,0.1f, 1000.f);
glUniformMatrix4fv(location_projectionMatrix, 1, GL_FALSE, glm::value_ptr(projectionMatrix));
// Set ModelViewMatrix
glm::mat4 identity = glm::mat4(1.0);
glm::mat4 viewTranslate = glm::translate(identity, glm::vec3(0.0f, 0.0f, -translate_z));
glm::mat4 viewRotateX = glm::rotate(viewTranslate, rotate_x, glm::vec3(1.0f, 0.0f, 0.0f));
glm::mat4 viewRotateY = glm::rotate(viewRotateX, rotate_y, glm::vec3(0.0f, 1.0f, 0.0f));
modelViewMatrix = viewRotateY;
glUniformMatrix4fv(location_modelViewMatrix, 1, GL_FALSE, glm::value_ptr(modelViewMatrix));
I tried to just translate the cube by -32 into the x and y direction, but without success.
Matrix operations are non commutative .It means that doing translation first and then rotation is not the same as doing rotation and then translation.Usually the order is :scale-> rotation -> translation.
So try this instead:
glm::mat4 viewRotateX = glm::rotate(identity, rotate_x, glm::vec3(1.0f, 0.0f, 0.0f));
glm::mat4 viewRotateY = glm::rotate(viewRotateX, rotate_y, glm::vec3(0.0f, 1.0f, 0.0f));
glm::mat4 viewTranslate = glm::translate(viewRotateY , glm::vec3(0.0f, 0.0f, -translate_z));
Related
I am trying to rotate my camera from it's position but around the Y axis. If anyone has any ideas
please let me know. Whenever I use the glm rotate function I am faced with this issue in it's third
parameter.
glm::mat4 xlook(1.0f);
glm::vec3 position(0.05f, 0.05f, -1.0f);
glm::vec3 viewdirection(0.0f, 0.0f, -1.0f);
glm::vec3 UP(0.0f, 1.0f, 0.0f);
xlook = glm::rotate(xlook, leftright, UP);
glm::mat3 rot = glm::mat3(xlook);
viewdirection = rot * viewdirection;
glm::mat4 views;
glm::mat4 trans1(1.0f);
trans1 = glm::rotate(trans1, 0.0f, glm::vec3(0.0f, 1.0f, 0.0f));
trans1 = glm::rotate(trans1, 0.0f, glm::vec3(4.0f, 0.0f, 0.0f));
trans1 = glm::scale(trans1, glm::vec3(Thescale,Thescale, 0.0f));
trans1 = glm::translate(trans1, glm::vec3(0.0f, 0.0f, Thetranslation));
views = glm::lookAt(position, position + viewdirection, UP);
I'm making a solar system in OpenGL and I want the planets to be able to orbit other planets as well as rotate around their own centers.
This is the code I'm currently using to make the planets orbit a specific point:
Model = glm::translate(Model, glm::vec3(-orbit_radius_, 0.0f, 0.0f));
Model = glm::rotate(Model, glm::radians(orbit_speed_) / 100.0f, glm::vec3(0.0f, 1.0f, 0.0f));
Model = glm::translate(Model, glm::vec3(orbit_radius_, 0.0f, 0.0f));
How would I combine this with a transformation that spins the object around itself?
I got it to work by just splitting then transformations and then combining them at the end.
rotate_ = glm::translate(rotate_, glm::vec3(-orbit_radius_, 0.0f, 0.0f));
rotate_ = glm::rotate(rotate_, glm::radians(orbit_speed_) / 100.0f, glm::vec3(0.0f, 1.0f, 0.0f));
rotate_ = glm::translate(rotate_, glm::vec3(orbit_radius_, 0.0f, 0.0f));
spin_ = glm::rotate(spin_, glm::radians(spin_speed_) / 100.0f, glm::vec3(0.0f, 1.0f, 0.0f));
final_ = rotate_ * spin_;
If you want to spinn and rotate an object, the I recommend to create an object which has its center at (0, 0, 0)
The self spinning of the object has to be do first. Then translate and rotate the object:
Model = rotate * translate * spinn
e.g.:
rot_angle += glm::radians(orbit_speed_) / 100.0f;
spin_angle += glm::radians(orbit_speed_) / 100.0f;
glm::vec3 tvec = glm::vec3(orbit_radius_, 0.0f, 0.0f);
glm::vec3 axis = glm::vec3(0.0f, 1.0f, 0.0f)
glm::mat4 translate = glm::translate(glm::mat(1.0f), tvec);
glm::mat4 rotate = glm::rotate(glm::mat(1.0f), rot_angle, axis);
glm::mat4 spin = glm::rotate(glm::mat(1.0f), spin_angle , axis);
Model = rotate * translate * spin;
With this solution rot_angle and spin_angle have to be incremented in every frame by a constant step.
If you don't want to increment the angles, then you have to store 2 matrices, instead of the angles. 1 for the rotation and on for the spin:
mat4 rotate(1.0f);
mat4 spin(1.0f);
glm::vec3 tvec = glm::vec3(-orbit_radius_, 0.0f, 0.0f);
glm::vec3 axis = glm::vec3(0.0f, 1.0f, 0.0f)
float rot_angle = glm::radians(orbit_speed_) / 100.0f;
float spin_angle = glm::radians(spin_speed_) / 100.0f;
rotate = glm::translate(rotate, tvec);
rotate = glm::rotate(rotate, rot_angle, axis );
rotate = glm::translate(rotate, -tvec);
spin = glm::rotate(spin, spin_angle, axis);
Model = rotate * spin;
I want to rotate my camera around the scene and an object which is in the center. I've tried doing it this way:
glm::mat4 view;
float radius = 10.0f;
float camX = sin(SDL_GetTicks()/1000.0f) * radius;
float camZ = cos(SDL_GetTicks()/1000.0f) * radius;
view = glm::lookAt(glm::vec3(camX, 0.0f, camZ), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
glUniformMatrix4fv(glGetUniformLocation(shader, "viewingMatrix"), 1, false, &view[0][0]);
but my object loads up further away on the screen and the object rotates around the scene, not the camera.
That's my vertex shader:
void main()
{
FragPos = vec3(modelMatrix * vec4(aPos, 1.0));
Normal = mat3(transpose(inverse(modelMatrix))) * aPos;
TexCoord = aTexture;
vec4 transformedPosition = projectionMatrix * viewingMatrix * vec4(FragPos, 1.0f);
gl_Position = transformedPosition;
}
How do I make it such that the camera is the one rotating around in the scene without the object rotating around?
I'm following this tutorial and I'm trying to work out the what happens in the first animation.
https://learnopengl.com/Getting-started/Camera
modelMatrix
glm::mat4 modelMat(1.0f);
modelMat = glm::translate(modelMat, parentEntity.position);
modelMat = glm::rotate(modelMat, parentEntity.rotation.z, glm::vec3(0.0f, 0.0f, 1.0f));
modelMat = glm::rotate(modelMat, parentEntity.rotation.y, glm::vec3(0.0f, 1.0f, 0.0f));
modelMat = glm::rotate(modelMat, parentEntity.rotation.x, glm::vec3(1.0f, 0.0f, 0.0f));
modelMat = glm::scale(modelMat, parentEntity.scale);
int modelMatrixLoc = glGetUniformLocation(shader, "modelMatrix");
glUniformMatrix4fv(modelMatrixLoc, 1, false, &modelMat[0][0]);
The target of the view (2nd parameter of glm::lookAt) should be the center of the object. The position of the object (and the center of the object) is changed by the model matrix (modelMatrix) in the vertex sahder.
You have to add the world position of the object to the 1st and 2nd parameter of glm::lookAt. The position of the object is the translation of the model matrix.
Further the object is to far away from the camera, because the radius is to large.
To solve your issue, the code has to look somehow like this:
glm::mat4 view;
float radius = 2.0f;
float camX = sin(SDL_GetTicks()/1000.0f) * radius;
float camZ = cos(SDL_GetTicks()/1000.0f) * radius;
view = glm::lookAt(
glm::vec3(camX, 0.0f, camZ) + parentEntity.position,
parentEntity.position,
glm::vec3(0.0f, 1.0f, 0.0f));
glUniformMatrix4fv(
glGetUniformLocation(shader, "viewingMatrix"), 1, false, glm::value_ptr(view));
I'm modelling the solar system and testing the orbit of the Earth around the Sun, using orthogonal projection.
The starting point of the Earth is to the right of the Sun, direction of moving is to the left hand side. But the Earth is not completely rendered when it is in front of the Sun and when go further behind the Sun, as you can see from 3 images below:
Starting point:
Next frame:
Final frame:
Can some one explain what exactly happening here? I think this is the cull face problem, I tried:
glEnable(GL_CULL_FACES);
glCullFace(GL_FRONT);
It doesn't work actually.
This is my code:
// global vars
int width = 1820, height = 960;
#define CENTRE_X static_cast<float>(width/2)
#define CENTRE_Z static_cast<float>(-height/2)
#define EARTH_SIZE glm::vec3(30.0f, 40.0f, 30.0f)
#define SUN_SIZE EARTH_SIZE*3.0f
void renderSun(int i){
glPushMatrix();
glLoadIdentity();
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture_ID[0]);
glUniform1i(texture_Location, 0);
glm::mat4 Projection = glm::ortho(0.0f, static_cast<float>(width), 0.0f, static_cast<float>(height), 0.0f, 100.0f);
glm::mat4 View = glm::lookAt(
glm::vec3(0, 120, 1),
glm::vec3(0, 0, 0),
glm::vec3(0, 1, 0)
);
/* Animations */
GLfloat angle = (GLfloat) (i);
View = glm::translate(View, glm::vec3(static_cast<float>(width/2), 0.0f, static_cast<float>(-height/2)));
View = glm::scale(View, SUN_SIZE);
View = glm::rotate(View, angle * 0.5f, glm::vec3(0.0f, 0.0f, 1.0f));
/* ******* */
glm::mat4 Model = glm::mat4(1.0f);
glm::mat4 MVP = Projection * View * Model;
glUniformMatrix4fv(glGetUniformLocation(shaderProgram, "mvpMatrix"), 1, GL_FALSE, glm::value_ptr(MVP));
glDrawElements(GL_TRIANGLES, numsToDraw, GL_UNSIGNED_INT, NULL);
glPopMatrix();
}
void renderEarth(int i){
glPushMatrix();
glLoadIdentity();
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture_ID[3]);
glUniform1i(texture_Location, 0);
glm::mat4 Projection = glm::ortho(0.0f, static_cast<float>(width), 0.0f, static_cast<float>(height), 0.0f, 100.0f);
glm::mat4 View = glm::lookAt(
glm::vec3(0, 150, 1),
glm::vec3(0, 0, 0),
glm::vec3(0, 1, 0)
);
/* Animations */
GLfloat angle = (GLfloat) (i);
View = glm::translate(View, glm::vec3(cos(orbitPos)*150, sin(orbitPos)*150, 0.0f));
View = glm::translate(View, glm::vec3(CENTRE_X, 0.0f, CENTRE_Z));
View = glm::scale(View, EARTH_SIZE);
View = glm::rotate(View, angle * 0.5f, glm::vec3(0.0f, 0.0f, 1.0f));
/* ******* */
glm::mat4 Model = glm::mat4(1.0f);
orbitPos += 0.005;
glm::mat4 MVP = Projection * View * Model;
glUniformMatrix4fv(glGetUniformLocation(shaderProgram, "mvpMatrix"), 1, GL_FALSE, glm::value_ptr(MVP));
glDrawElements(GL_TRIANGLES, numsToDraw, GL_UNSIGNED_INT, NULL);
glPopMatrix();
}
You are using inconsistent View matrices, your code is essentially rotating the view of the earth, which causes it to move relative to the sun. This is very unusual way to do things, and is probably the cause of your problems. It is (presumably) causing the models to collide in clip space, and intersect with one another. You should instead use the same View matrix for both, and modify the Model matrix for the earth model. Keeping the renderSun method the same, you could do this by modifying renderEarth:
void renderEarth(int i){
//...
/* Animations */
GLfloat angle = (GLfloat) (i);
glm::mat4 M0 = glm::translate(View, glm::vec3(cos(orbitPos)*150, sin(orbitPos)*150, 0.0f));
glm::mat4 M1 = glm::translate(View, glm::vec3(CENTRE_X, 0.0f, CENTRE_Z));
glm::mat4 M2 = glm::scale(View, EARTH_SIZE);
glm::mat4 M3 = glm::rotate(View, angle * 0.5f, glm::vec3(0.0f, 0.0f, 1.0f));
/* ******* */
orbitPos += 0.005;
glm::mat4 MVP = Projection * View * M3 * M2 * M1 * M0;
// ...
I'm trying to set up an orthographic view matrix using glm and pass it to glsl. this poster has the same problem, I want to be able to render pixels drawn further away from the camera but they are being clipped when they are anything but 1.0 distance.
The MVP matrix is set up like so:
// Setup MVP Matrix
glm::mat4 model = glm::mat4(1.0);
model = glm::translate(model, glm::vec3(sprite->getPositionX(), sprite->getPositionY(), 0.0f));
model = glm::rotate(model, rotation, glm::vec3(0.0f, 0.0f, 1.0f));
model = glm::translate(model, glm::vec3(-sprite->getOffsetX(), -sprite->getOffsetY(), 0.0f));
//model = glm::scale(model, glm::vec3(1.0f, 1.0f, 1.0f)); // Unused for now
glm::mat4 view = glm::lookAt(glm::vec3(0,0,0), glm::vec3(0,0,-1), glm::vec3(0,1,0));
glm::mat4 projection = glm::ortho(0.0f, 800.0f, 600.0f, 0.0f, 1.0f, 1000.0f);
glm::mat4 mvp = projection * view * model;
// Set mpv matrix in shader
GLint mvpLoc = glGetUniformLocation(this->m_shader, "u_mvpMatrix");
glProgramUniformMatrix4fv(this->m_shader, mvpLoc, 1, GL_FALSE, &mvp[0][0]);
I can see the quad being rendered with the translation and rotation applied but when the verticies are anywhere but -1.0f on the z axis they are not drawn when I expect it to draw anything from -1.0 to -1000.0 units away as specified in the call to glm::ortho. Anybody know how this can be achieved?