With below instructions, I can strafe camera left-right, up-down and can rotate pitch+yaw using mouse and keyboard but I couldnt move forward or backwards:
Starting of drawing:
GL11.glMatrixMode(GL11.GL_PROJECTION);
GL11.glLoadIdentity();
GL11.glTranslatef((-(float)horizontalstrafe)*0.15f, (-(float)verticalstrafe)*0.15f, 0);
GL11.glTranslatef(0, 0, ((float)-forward)*0.15f);// does not move!
GL11.glRotatef((float)mouseAngleY, -0.02f, 0, 0);
GL11.glRotatef((float)mouseAngleX, 0, 0.02f, 0);
Why doesnt it move? When I press the necessary button, it just disappears after sometime and get visible again if I press opposite button for enough time.
Init part:
GL11.glMatrixMode(GL11.GL_MATRIX_MODE);
GL11.glLoadIdentity();
GL11.glOrtho(-2.0 * aspect, 2.0 * aspect, -2.0, 2.0, 0.1f, 3.0f);
Note: the object I need to see has vertices between the boundaries of x:[-1,1], y:[-1,1], z:[-1,1]
Related
I have the code for a room provided to me, I need to add a sphere in the room. It goes like this:
PushMatrix();
//draw floor,walls,ceilings
PushMatrix();
//draw some boxes on front wall
PopMatrix();
PushMatrix();
//drawing sphere;
glLoadIdentity();
glColor3f(1, 0, 0);
glTranslatef(0, ypos, 0);
glutSolidSphere(2, 20, 20);
PopMatrix();
PopMatrix();
But all the walls etc turn red (and no sphere) when I do this. Why does that happen even after pushing another matrix?
Calling glColor*() sets the current color. This color doesn't change before you call glColor*() again. In other words glPushMatrix() and glPopMatrix() has no effect on the current color.
Thus if you in //draw some boxes on front wall don't call glColor*(). Then due to you setting the color to red by calling glColor3f(1, 0, 0) then everything is going to be red from that point on.
Considering:
glMatrixMode(GL_PROJECTION);
gluPerspective(40, 1, 1, 40);
glMatrixMode(GL_MODELVIEW);
Then:
glPushMatrix();
glTranslatef(0, 0, -10);
glColor3f(1, 0, 0);
glutSolidSphere(2, 20, 20);
glPopMatrix();
By doing the above you should see a sphere.
Thus if you before didn't see the sphere at all. Then it's probably due to ypos being outside your view. If you were referring to the whole screen being red, then I'm assuming ypos to be around 0, which means that it would be filling the whole screen (Again assuming you don't translate the view in any other way).
I am rather new to programming so I may not use the correct terminology. I am trying to create a dog out of only glutwirecubes, however I cannot figure out how to define a starting position for the back legs, nor can I figure out how to close the space between my 'shoulder' and 'elbows'. I have each body part assigned to rotate by key press. I also realize that my use of glPushMatrix and glPopMatrix may not be correct as I do not fully understand how the matrix stack is saved/loaded.
glPushMatrix();
glTranslatef(-1, 0, 0);
glRotatef((GLfloat)body,1, 0, 0);//sets rotations about x,y,z axis
glTranslatef(1, 0, 0);
glPushMatrix();
glScalef(2.0, 0.4, 0.5);//sets dimensions of cube
glutWireCube(2.0);//sets scale of wire cube
glPopMatrix();
glPopMatrix();
glPushMatrix();
glTranslatef(-1, 0, 0);
glRotatef((GLfloat)shoulder, 0, 0, 1);//sets rotations about x,y,z axis
glTranslatef(1, 0, 0);
glPushMatrix();
glScalef(1.5, 0.4, 0.5);//sets dimensions of cube
glutWireCube(.75);//sets scale of wire cube
glPopMatrix();
glTranslatef(1,0,0);
glRotatef((GLfloat)elbow,0,0,1);//sets rotations about x,y,z axis
glTranslatef(1,0,0);
glPushMatrix();
glScalef(1.5,0.4,0.5);//sets dimensions of cube
glutWireCube(.75);//sets scale of wire cube
glPopMatrix();
glPopMatrix();
glutSwapBuffers();
The picture is the position I am aiming for, however my cubes always start oriented horizontally.
with glTranslate right before, as for its friends !
For instance you might translate so that the center is now at the corner, so that your rotations rotate around this new handle.
Okay, so my program opens a file, reads in xyz-points, then draws a line strip out of it. I originally had this program written in SharpGL (implemnted as WPF window) and it worked, but not well due to using immediate mode, so I have moved onto OpenGL in C++. I have (somewhat) figured out VBO's and I now I am trying to add mouse functionality now. My problem is I can't move the picture with my mouse, I want to be able to click and 'drag' the picture. My mouseClickFunc and mouseMotion work (my cout statements execute), however it seems like my translate call is never being executed (i.e. the picture starts partially 'clipped' in the scene and I would like the ability to drag it and center it). I know this is a shot in the dark but I am really not sure what to do.
MotionFunc:
void mouseMotion(int x, int y)
{
if (moveable)
{
xMove += xTransform(x) - xTransform(xDown);
yMove += yTransform(y) - yTransform(yDown);
xDown = x;
yDown = y;
cout << yMove << "---" << xMove << endl;
glutSwapBuffers();
glutPostRedisplay();
}
}
Display Function:
void RenderFunction(void)
{
++FrameCount;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glOrtho(xMin - 1, xMax + 1, yMin - 1, yMax + 1, -diameter * zScale, diameter * zScale);
// Reset the modelview matrix.
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glPushMatrix();
glTranslatef(xMove, -yMove, 0);
//glViewport((GLint)xMove*100, (GLint)-yMove*100, CurrentWidth, CurrentHeight);
//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDrawArrays(GL_LINE_STRIP, 0, 29000);
glPopMatrix();
glutSwapBuffers();
glutPostRedisplay();
}
I am sure there is more code that I need to show, this is just where I think the problem is. Any help would be greatly appreciated.
Here is a picture of a console output and the screen (OpenGL context) as I see it.
UPDATE: Updated my code. It looks like my coordinates are moving, but the picture is not if that makes sense. If you look at my output, if I keep 'dragging' the picture, you can see in the console that the variable xMove and yMove can get as large or small as they want, again translate is just never moving it.
You pop your matrix before drawing things, which resets the matrix to the state of last push matrix. Move glPopMatrix(); below draw call
You're popping the matrix before you call glDrawArrays(), so this naturally negates the effect of the translation. It also negates the glOrtho() call, but that should be issued on the projection matrix and not on the modelview matrix in the first place.
And, of course, the problem is in your code, and not in OpenGL.
In this code excerpt :
glLoadIdentity();
glPushMatrix();
glTranslatef(xMove, -yMove, 0);
//glViewport((GLint)xMove*100, (GLint)-yMove*100, CurrentWidth, CurrentHeight);
glOrtho(xMin - 1, xMax + 1, yMin - 1, yMax + 1, -diameter * zScale, diameter * zScale);
glPopMatrix();
//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDrawArrays(GL_LINE_STRIP, 0, 29000);
you are :
setting the identity as the view matrix
push it into the queue
modify it by glTranslate
pop it of the stack
render the image
Therefore, your translation is ignored.
This is correct operation :
glLoadIdentity();
glPushMatrix();
glTranslatef(xMove, -yMove, 0);
//glViewport((GLint)xMove*100, (GLint)-yMove*100, CurrentWidth, CurrentHeight);
glOrtho(xMin - 1, xMax + 1, yMin - 1, yMax + 1, -diameter * zScale, diameter * zScale);
//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDrawArrays(GL_LINE_STRIP, 0, 29000);
glPopMatrix();
You are multiplying projection before translation, remember to always read matrix transformation from bottome to top in OpenGL 1.1 which you should upgrade IMO. Another issue is that you are poping the matrix before drawing.
Correct code:
//glViewport((GLint)xMove*100, (GLint)-yMove*100, CurrentWidth, CurrentHeight);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(xMin - 1, xMax + 1, yMin - 1, yMax + 1, -diameter * zScale, diameter * zScale);
// Reset the modelview matrix.
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glPushMatrix();
glTranslatef(xMove, -yMove, 0);
//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDrawArrays(GL_LINE_STRIP, 0, 29000);
glPopMatrix();
UPDATE
See bottom for update.
I've been looking alot around the internet and I have found a few tutorials that explain what I'm trying to achieve but I can't get it to work, either the tutorial is incomplete or not applicable on my code.
I'm trying something as simple as rotating a 2D image around its origin (center).
I use xStart, xEnd, yStart and yEnd to flip the texture which are either 0 or 1.
This is what the code looks like
GameRectangle dest = destination;
Vector2 position = dest.getPosition();
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, this->image);
//If the rotation isn't 0 we'll rotate it
if (rotation != 0)
{
glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glTranslatef(0.5, 0.5, 0);
glRotatef(rotation, 0, 0, 1);
glMatrixMode(GL_PROJECTION);
}
glBegin(GL_QUADS);
glTexCoord2d(xStart,yStart);
glVertex2f(position.x, position.y);
glTexCoord2d(xEnd,yStart);
glVertex2f(position.x + this->bounds.getWidth(), position.y);
glTexCoord2d(xEnd,yEnd);
glVertex2f(position.x + this->bounds.getWidth(), position.y + this->bounds.getHeight());
glTexCoord2d(xStart,yEnd);
glVertex2f(position.x, position.y + this->bounds.getHeight());
glEnd();
glDisable(GL_TEXTURE_2D);
//Reset the rotation so next object won't be rotated
glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glRotatef(0, 0, 0, 1);
glMatrixMode(GL_PROJECTION);
This code will draw the image in it's original size and it will rotate it, but it will rotate it from the top left corner which crops the image a lot. By calling GameRectangle.getOrigin() I can easily get the center of the rectangle, but I don't know where to use it.
Bit if put:
glTranslatef(-0.5, -0.5, 0);
After I call the:
glRotatef(0.5, 0.5, 0);
It will rotate from the center, but it will strech the image if it's not a perfect 90 degrees rotation.
UPDATE
After trying pretty much everything possible, I got the result I was looking for.
But I'm not sure if this is the best approach. Please tell me if there's something wrong with my code.
As I mentioned in a comment above, I use the same image multiple times and draw it with different values, so I can't save anything to the actual image. So I must reset the values everytime after I have rendered it.
I changed my code to this:
//Store the position temporary
GameRectangle dest = destination;
Vector2 position = dest.getPosition();
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, this->image);
glTranslatef(dest.getOrigin().x, dest.getOrigin().y, 0);
glRotatef(rotation, 0, 0, 1);
glBegin(GL_QUADS);
glTexCoord2d(xStart,yStart);
glVertex2f(-dest.getWidth()/2, -dest.getHeight()/2);
glTexCoord2d(xEnd,yStart);
glVertex2f(dest.getWidth()/2, -dest.getHeight()/2);
glTexCoord2d(xEnd,yEnd);
glVertex2f(dest.getWidth()/2, dest.getHeight()/2);
glTexCoord2d(xStart,yEnd);
glVertex2f(-dest.getWidth()/2, dest.getHeight()/2);
glEnd();
//Reset the rotation and translation
glRotatef(-rotation,0,0,1);
glTranslatef(-dest.getOrigin().x, -dest.getOrigin().y, 0);
glDisable(GL_TEXTURE_2D);
This rotates the texture together with the quad it's drawn in, it doesn't strech or crop. However the edges are a bit jagged if the image is filled square but I guess I can't avoid that with out antialiasing.
What you want is this:
glPushMatrix(); //Save the current matrix.
//Change the current matrix.
glTranslatef(dest.getOrigin().x, dest.getOrigin().y, 0);
glRotatef(rotation, 0, 0, 1);
glBegin(GL_QUADS);
glTexCoord2d(xStart,yStart);
glVertex2f(-dest.getWidth()/2, -dest.getHeight()/2);
glTexCoord2d(xEnd,yStart);
glVertex2f(dest.getWidth()/2, -dest.getHeight()/2);
glTexCoord2d(xEnd,yEnd);
glVertex2f(dest.getWidth()/2, dest.getHeight()/2);
glTexCoord2d(xStart,yEnd);
glVertex2f(-dest.getWidth()/2, dest.getHeight()/2);
glEnd();
//Reset the current matrix to the one that was saved.
glPopMatrix();
Most of this code should be fairly self explanatory. I got an display function and my view port function. There are two modes which is 4 small view ports in the window or one large.
I got one camera which can be moved and if in 4 view port mode just 3 fixed angles. The thing is I want the free moving cameras position to be displayed in the 3 other view ports. I tried doing it by drawing spheres using opengl but the problem is that then the position gets draw in the free roaming camera too as it shows the same scene.
It doesn't have to be a sphere, just something simple that represents the cameras spacial position in these three other views.
Drawing the scene once with camera object showing for the three viewports, render to texture. Clear and draw scene without camera object render to texture and then stitch these together before actually drawing the scene seems like a lot o work for something that should be easy.
void display(int what)
{
if(what==5){
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
camControll();}
if(what==1){
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(75,15,-5,0,5,-5,0,1,0);}
if(what==2){
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0,110,0,0,0,0,1,0,0);}
if(what==3){
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, float(320) / float(240), 0.1f, 100.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
camControll();}
if(what==4){
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(185,75,25,0,28,0,0,1,0);}
glClearColor(0, 0, 0, 1);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
drawScene();
drawCamera();
glutSwapBuffers();
}
void viewport(){
glEnable(GL_SCISSOR_TEST);
if(!divided_view_port)
{
glViewport(0, 0, w, h);
glScissor(0,0,640,480);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 100.0f);
display(5);
}
else
{
////////////////////// bottom left - working
glViewport(0, 0, w/2, h/2);
glScissor(0,0,w/2,h/2);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 300.0f);
display(1);
//////////////////////
////////////////////// top right - working
glViewport(w/2, h/2, w/2, h/2);
glScissor(w/2,h/2,w/2,h/2);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 300.0f);
display(2);
//////////////////////
////////////////////// bottom right -working
glViewport(w/2, 0, w/2, h/2);
glScissor(w/2,0,w/2,h/2);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 300.0f);
display(3);
////////////////////////
////////////////////////// top left
glViewport(0, h/2, w/2, h/2);
glScissor(0,h/2,w/2,h/2);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 300.0f);
display(4);
///////////////////////////
}
glDisable(GL_SCISSOR_TEST);
glMatrixMode(GL_MODELVIEW);
}
So what I basically need is to hide this object in specific viewport.
Why not make that single Sphere object (or the entity responsible for drawing the sphere) aware of the "current viewport" (which happens to be the what variable in your code) and let it be invisible if it's the given viewport?
This solution exactly corresponds to the logic involved here sounds both simple and correct.
A more general solution would be to give each "camera" a GUID and make it available for the entity responsible for drawing Cameras to check the GUID of the "camera" bound to the viewport which is being rendered at the moment. If they happen to be equal, ignore the camera object during this draw pass.
I think that should be easy if you would just draw point, because if you want to see point in viewport, its center have to be in viewport, otherwise nothing of it is displayed even if you set huge point size. Then you have 2 options to eliminate flickering effect (as when you put 2 squares in the very same possition they will flicker one over another). You can just move that point little behind camera, or use nonzero value for near clipping plane in glFrustrum/gluPerspective call.. and well if you update point position every time you move camera you have no chance of seeing that point in your moving camera and you can use single scene.
And second option, I don't know if you can update just single viewport, but maybe just setting scene, displaying it to moving camera, drawing camera position and displaying it for other 3 viewports should be easy also..
Why don't you draw the sphere behind the moving camera's near plane? That should ensure that the moving camera doesn't see the sphere at all, but its position is clearly marked for the others.