I'm not sure if this is really a beginner topic or not, but since I'm not really experienced, I thought I'd post in beginners section just to be safe from ridicule.

I'm writing some practice applications and am having a blast. I'm wanting to build some neat game-apps (mostly just experimenting right now) and I do want to get some good game design in whatever I do. These are questions I have, and any answers would be great!

Question 1: Animation

Is it possible to export animations from 3ds Max? Also, how would this work? I've messed around with .obj files, and I can load in an object with textures into my application, but I am unsure how to do animation. Do I need some kind of bone system - or perhaps a bunch of .obj's with difference vertex positions for each frame? I prefer the vertex positions per frame, as the bone stuff seems like it might make the computer do a little more math than I'd like it to.

Question 2: Data Structure(s)

I'd like to make a RTS, which means I need a lot of "Units" (I'd likely make unit objects) and I'd like a lot of these, hundreds, maybe thousands. As you can tell, I have no grasp on what's feasible here, in terms of how it's usually done in games, so I'd like to know if I'm way off, or if there's a special way to do it.

In all honesty, I plan to have all units contained in a <vector> and loop through each one, progressing its state forward a frame (like walking, or attacking)

Question 3: Visual Studio - DLL's and .libs

I'm quite use to having a bunch of .h and .cpp files all in a project, and compiling the whole thing into an exe (with .obj's and png's in the same directory). Should I have bunches of my code put into a seperate file and export as DLL? I haven't done this before, so is there anything I need to know about this? (I think exporting a dll is pretty easy, just have to change a setting)

Question 4: Input to Logic

- Solved

Question 5: Mouse/screen coords to the 3d world

- Solved

Question 6: Mouse/screen projection is off

So I got the program to cast a ray from the mouse into the 3d world - However it's off by a few pixels, and this seems to occur in the actual 3d world.

The cyan-Hlighlighted square should be directly underneath the mouse.

Below I have drawn the mouse position into this screen capture of my program (because printscr doesnt copy the cursor)

As you can see it's off by a fair margain, but it's pretty damn close. I mean, I can use this program and it's quite nice, but the offset doesn't make any sense.

Here's the code to convert mouse coords into 3d world coords

vector3d GetOGLPos(int x, int y, float z)
{
GLint viewport[4]; // contains x, y, width and height
GLdouble modelview[16]; // modelview matrix information
GLdouble projection[16]; // projection matrix information


glGetIntegerv(GL_VIEWPORT, viewport);
glGetDoublev(GL_MODELVIEW_MATRIX, modelview);
glGetDoublev(GL_PROJECTION_MATRIX, projection);


GLfloat winX, winY, winZ;
    GLdouble posX, posY, posZ;


winX = (GLdouble)x;
winY = (GLdouble)viewport[3] - (GLdouble)y;
winZ = (GLdouble)z;


    gluUnProject( winX, winY, winZ, modelview, projection, viewport, &posX, &posY, &posZ);


    return vector3d(posX, posY, posZ);
}

it's used like so:

// mousePosNear and mousePosFar are of type "vector3d"

mousePosNear = GetOGLPos(m_mouseX, m_mouseY, 0.0);
mousePosFar = GetOGLPos(m_mouseX, m_mouseY, 1.0);

I'm not sure if I should provide other details, such as the rayplane function that these values are used in. Let me know if you want that code aswell to help solve this

Question 7: Deciding what tiles to draw

Actually this problem seems like it should be relatively easier Since I already have the rayplane function done, but I can't figure out how to do this in 3d (the 3d math just does my head in)

I figured It would be something like casting a ray from each corner of the screen and getting the returned tile... and then I don't know what to do from there.

so there's not really a way to avoid skeletal animation system when doing animations in 3d.

I was thinking maybe I could do all the animation inside 3ds max with bones and ik's etc, and then just export the end result (vertex positions) of each frame. I don't know if this is possible, but I don't see why not.

I was thinking maybe I could do all the animation inside 3ds max with bones and ik's etc, and then just export the end result (vertex positions) of each frame. I don't know if this is possible, but I don't see why not.

There is a number of reasons. If you have a look at how big a high (and even low) poly model file can get, you'll see why. For a 10 second animation â 60 frames it would take an enormous amount of memory. Not talking about loading time - you would have to load the whole model for every step of the animation, which eigther takes up gigs of ram for each model or requires loading data from the disk every frame, which is a very bad thing to have and will make your game virtually unplayable.

Next thing, you want smooth interpolation based on the target PCs frame rate - if you'd e.g really export a 10 second character animation the way you wanted to do, just think about how you would (not be able to) handle animation on one PC that runs the game at 500 FPS and another one that only has 15 FPS. Skeletal animation takes (almost) automatically care of this, while with your approach this would be nearly impossible/even harder to achieve than just implementing SA.

If thats not enough, think about if you have a standard walk animation and then want your character to turn his head on one occassion. SA you can blend different animations. but with the way you suggested, you'd have to dublicate the walk animation with his head turned exactly at the right moment - stepping back to the memory workload I talked about earlier, I suppose you plan on shipping your game on a 1 TB HDD? ;)

Short answer - no, this is not at all possible, even if modeling software would support it (which it, fortunately, in my knowledge doesn't).

Just as a small observation, what you're calling "logic.cpp" is in fact the input portion of your program. This would run in the input function of your game loop, while logic is a separate function of the game loop that would run after the input.

If thats not enough, think about if you have a standard walk animation and then want your character to turn his head on one occassion. SA you can blend different animations. but with the way you suggested, you'd have to dublicate the walk animation with his head turned exactly at the right moment - stepping back to the memory workload I talked about earlier, I suppose you plan on shipping your game on a 1 TB HDD? ;)

Short answer - no, this is not at all possible, even if modeling software would support it (which it, fortunately, in my knowledge doesn't).

While I agree that skeletal animation is the best way to go about this (and all your reasons why are valid), interpolating between keyframes of the model was a common way of doing 3D animations in the early days of 3D. In these days the poly count and number of animations was minuscule compared to today's standards so the memory problems could be worked around.

Interesing to know, I though keyframe interpolation was only used for e.g. technical mechanisms etc...

Question 5: Mouse/screen coords to the 3d world

So I've kinda done some of the harder work already. Here is my application so far:

myprog.jpg



A ray is cast from the camera in whatever direction it's pointing and highlights whatever tile it hits. In a way, you could imagine that the mouse pointer is always in the centre of the screen.



How would I add to this code to instead have the mouse highlight the tiles(as in, wherever the mouse is on screen, translate that into the 3d world). I can already get the mouse coords on the screen using an SDL function, just need to know the math.

-Also, if I've not provided sufficent information for this problem (like if you want to see my rayplane function) please let me know. I'm not sure what information is relevant here.



Some Info:



class smCamera
{
private:
vector3d loc;
float camPitch, camYaw;



the vector3d loc is just the camera location. It has floats x, y and z



camPitch is the up and down rotation, and camYaw is the left and right rotation. These are applied graphically like so:



glTranslatef(0.0, 0.0, -(player->cam->getCamY())); // Distance up from the ground
glRotatef(player->cam->getPitch(), 1.0, 0.0, 0.0); // I have this set at -45 to look down
glRotatef(-(player->cam->getYaw()), 0.0, 1.0, 0.0); // I increase this with the shift keys
glTranslatef(-(player->cam->getCamX()), 0.0, -(player->cam->getCamZ())); // translate the world

Help is greatly appreciated!

You need to unproject your mouse position. I can't tell you how it exactly works with OpenGL, but I can give you some DirectX-code with a little explanation, you should be able to figure out the rest yourself:

	//todo: access camera differently
	const Camera* pCamera = m_pGfx3D->GetCamera();

	//todo: access cursor differently
	Vector2 mousePos = Input::GetMousePos();
        //translate mouse coordinates to scene area
	mousePos.x -= m_pArea->GetX();
	mousePos.y -= m_pArea->GetY();
	D3DXVECTOR3 vMouse((float)mousePos.x, (float)mousePos.y, 0.0f);
	D3DXVECTOR3 vMouse2((float)mousePos.x, (float)mousePos.y, 1.0f);
	const D3DVIEWPORT9& ViewPort(m_pGfx3D->GetViewport());

	D3DXMATRIX mWorld;
	D3DXMatrixIdentity(&mWorld);

	D3DXVECTOR3 vP1, vP2;
	D3DXVec3Unproject(&vP1, &vMouse, &ViewPort, &pCamera->GetProjectionMatrix(), &pCamera->GetViewMatrix(), &mWorld); 

	D3DXVec3Unproject(&vP2, &vMouse2, &ViewPort, &pCamera->GetProjectionMatrix(), &pCamera->GetViewMatrix(), &mWorld); 

	D3DXVECTOR3 vDist = vP2;
	vDist -= vP1;
	D3DXVec3Normalize(&vDist, &vDist);

	const Ray mouseRay(vP1, vDist);

You basically create two points from the mouse, one on the near and one on the far clip plane. Now given the view matrix, projection matrix, viewport and (most likely identity) world matrix you can unproject these two points to their location in the world. You then construct your ray from these two points an voîla, you're done.