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15
votes
1answer
594 views

Keystone Correction using 3D-Points of Kinect

With XNA, I am displaying a simple rectangle which is projected onto the floor. The projector can be placed at an arbitrary position. Obviously, the projected rectangle gets distorted according to the ...
14
votes
5answers
4k views

Do I need the 'w' component in my Vector class?

Assume you're writing matrix code that handles rotation, translation etc for 3d space. Now the transformation matrices have to be 4x4 to fit the translation component in. However, you don't actually ...
14
votes
3answers
2k views

Faking isometric graphics in a 2D space game

First off, I know exactly what my drawing problem is, and I have various ideas on how to approach solving it. I am here to figure out how to adjust which frame is drawn so that the isometric ...
13
votes
1answer
369 views

Orthographic unit translation mismatch on grid (e.g. 64 pixels translates incorrectly)

I am looking for some insight into a small problem with unit translations on a grid. Update and Solved I solved my own issue. See below for details. Everything in this part of the post turned out to ...
12
votes
3answers
846 views

Camera for 2.5D Game

I'm hoping someone can explain this to me like I'm 5, because I've been struggling with this for hours and simply cannot understand what I'm doing wrong. I've written a Camera class for my 2.5D game. ...
10
votes
1answer
2k views

Screen space to world space

I am writing a 2D game where my game world has x axis running left to right, y axis running top to bottom, and z axis out of the screen: Whilst my game world is top-down, the game is rendered on a ...
8
votes
3answers
2k views

What is the name of perspective of Age of Empires II?

One would describe Age of Empires 1's "perspective" as a 2D sprite game (screenshot). Below is a screenshot of Age of Empires II. How would you describe the "perspective"? Is it also a 2D sprite ...
8
votes
1answer
561 views

Projected trajectory of a vehicle?

In the game I am developing, I have to calculate if my vehicle (1) which in the example is travelling north with a speed V, can reach its target (2). The example depict the problem from atop: There ...
8
votes
1answer
469 views

Downprojecting an imaginary 4D mesh to the screen

As a mental exercise, I'm trying to imagine projecting an arbitrary 4D mesh onto the screen (2D). I'm guessing a single 4D triangle would still consist of only 3 points, however each of those 3 ...
8
votes
3answers
830 views

Inverted textures

I'm trying to draw textures aligned with this physics body whose coordinate system's origin is at the center of the screen. (XNA)Spritebatch has its default origin set to top-left corner. I got the ...
7
votes
2answers
488 views

Portal Projection

Ok ok I admit, I'm bored and toying with a portal script like the one on steam. I've figured out the following: relative positioning of the mirrored cameras render to texture for the portal (the ...
6
votes
1answer
4k views

Help understanding gluLookAt()

I am fairly new to openGL( 3 months ) and am asking for assistance in understanding the fundamentals behind gluLookAt(). Currently I have spent most of my time with openGL modeling scenes with fixed ...
6
votes
3answers
858 views

Arbitrary projection matrix from 6 arbitrary frustum planes

A projection matrix represent a tranformation from the camera view space to the rendering system clip space. In other words, it defines the transormation between a 6-sided frustum to the clip cube. ...
5
votes
2answers
914 views

What's a pre-multiplied 4x4 matrix?

I'm using a 3d game engine, that uses a 4x4 matrix to modify the camera projection. The matrix is in the regular 4x4 format: r r r x r r r y r r r z - - - zoom The description for the ...
5
votes
3answers
409 views

How can I calculate where my camera can be to avoid showing something outside a region?

I have a landscape model, which goes from the coordinate -45, -45 to 90, 90. The edge of the model just cuts off and i would like to somehow stop the screen from ever passing these points. Basically ...
5
votes
2answers
609 views

Draw a 3D object at specific coordinates on the screen

I'm creating an application which allows the user to manipulate 3D models. I would like to draw 3 axis representing the world coordinate system in 3D in order to give the user an idea where he is. ...
5
votes
1answer
146 views

Composite 3-D and 2-D using Anamorphic Projection?

I'm working on a game which takes place on a two dimensional grid similar to the fluid background grid in Geometry Wars. It is implemented as a procedurally drawn spring system which may have force ...
5
votes
2answers
300 views

Calculate new coords of camera after a 90 degree rotation in an isometric 2D projection

I made a 2D isometric renderer. It works fine but now I want to show my scene from 4 different points of view (NE NW SE SW) but, on a 90° rotation, my camera cannot keep the center of my scene on ...
4
votes
2answers
698 views

If I project a sphere in 3D will it be a circle?

Assuming I have infinite vertices to represent the sphere, if I project the sphere from any position/scale in 3D to 2D, will it be a circle? I know it will not be a circle on the screen, because of ...
4
votes
1answer
173 views

How do I ensure that perspective and orthographic projection matricies show objects at the same size on the screen?

I am working on a 3d scene editor and would like to show the scene in orthographic projection. My current problem is that I am not sure how to calculate the orthographic projection matrix such that ...
3
votes
1answer
1k views

Can a 4x4 matrix describe a camera's perspective?

I'm working with a closed-source 3D engine, and it only allows you to set the view projection via a 4x4 matrix. Can this matrix describe the camera's translation, rotation & perspective? I turned ...
3
votes
2answers
156 views

What kind of projection is ScreenX=X/Z, ScreenY=Y/Z?

I have an existing class which transforms 3D vectors and projects them on a 2D plane (Camera). The code is all written in C without help from an external library. To project a single vector (X,Y,Z) ...
3
votes
2answers
589 views

XNA - Non perspective projection?

For a section of my game, instead of having a perspective projection, i would like to display an isometric view of an object. So i don't want things to appear smaller if in a distance, etc. ...
3
votes
1answer
2k views

How do I create a decal system?

I'm currently given the task to design & create a simple decal-system in C++/DirectX. Does anybody know a great tutorial, article or paper to start with? (Especially the part about 2D-texture to ...
3
votes
1answer
384 views

Does the projection matrix flip winding order in right handed systems?

I am using a right handed coordinate system for my world coordinates (so, positive x goes right, y is up, and z is towards you). However, after projection and the w divide, nomalised device ...
3
votes
1answer
563 views

Perspective projection with 90 degrees between X-Y axis?

I'm trying to create a game that mimics Tibia's projection style: , As you can see, a 3d point is mapped to 2d like this: So I've downloaded Three.JS and a lib to create a Orthographic Camera. But ...
3
votes
1answer
143 views

Shear transformation in the projection matrix?

I am trying to understand what the shear transformation (l+r/r-l & b+t/t-b) is actually doing in the projection matrix? The only thing I got till now is headache :) Can you please help?
3
votes
1answer
410 views

How to calculate FOV with four-walled tiles?

I'm working on a 2D tile-based game. I'm trying to calculate FOV and I've implemented walls so they don't take up an entire tile. Instead, they just take up a side of each tile. Similar to: class ...
3
votes
1answer
269 views

How to do perspective projection “parallax” but without changing the scale or offset of objects?

Hello everyone I have this problem that I have tried everything I could think of. The problem: I am making a 2D game with parallax effect but I am using 3d space so am not simulating the parallax but ...
3
votes
1answer
426 views

Silly question about perspective correct texture mapping

OK, I'll admit, the math on a perspective projection matrix is quite hairy for me, but I get the general gist of it: morph the object so that it looks... perspective-ish. But there is one thing which ...
3
votes
2answers
511 views

Draw a projection of a mesh on a surface

I have a mesh looking almost like a cylinder, the cylinder goes through a mesh and continues on the other side. What I want to do is to draw the projection of the cylinder on the mesh. So if you look ...
3
votes
1answer
354 views

How to compute the 2D equations of 3D circular arcs?

I'd like to obtain these equations for the ellipses produced by the perspective projections of (3-dimensionally transformed) circles. This is useful for rendering in 2D contexts which provide curve ...
2
votes
2answers
229 views

What kind of projection is used here?

Tibia is a 2d game, but it's sprites are drawn using certain kind of orthographic projection that is not the same I'm used to: I'm trying to figure out what projection is used here. I've guessed ...
2
votes
2answers
1k views

How should I calculate world and projection matrices in this scenario?

I'm trying to understand transformation matrices. Suppose I use the camera from this StackOverflow answer, this is how my view matrix would look: Matrix.Identity * ...
2
votes
3answers
564 views

Game Engine which can provide 360 degree projection for PC [closed]

I'm searching Game engine which can provide 360 degree real-time projection. I've already achieved this by using VBS2 Game Engine. (Ref.: ...
2
votes
1answer
116 views

Is it bad-practice using left-handed coordinate system in OpenGL eye-space?

In the engine I am currently programming I want to use a left-handed coordinate system for eye-space instead of the glFrustum standard right-handed one. Is that in anyway considered bad practice?
2
votes
1answer
647 views

How to create projection/view matrix for hole in the monitor effect

Lets say I have my XNA app window that is sized at 640 x 480 pixels. Now lets say I have a cube model with its poly's facing in to make a room. This cube is sized 640 units wide by 480 units high by ...
2
votes
1answer
184 views

Coordinate spaces and transformation matrices

I'm trying to get an object from object space, into projected space using these intermediate matrices: The first matrix (I) is the one that transforms from object space into inertial space, but since ...
2
votes
2answers
81 views

Trying to project a point onto a cubemap

I've got a simple test program with a camera within a cubemap (skybox). You can look around, and it feels like you're in a 3D room, but really it's just a cubemap image. Now I want to draw a point ...
2
votes
1answer
102 views

Minimal Projection Matrix

i hope you can help me. I'm currently stuck at the creation process for projection matrices used by shadow maps. The problem is the following: I got the spot/directional light ...
2
votes
2answers
321 views

Unproject mouse position to tile — extremely jumpy position?

I'm trying to unproject the mouse position to get the position on the X-Z plane of a ray cast from the mouse. The camera is fully controllable by the user. Right now, the algorithm I'm using is... ...
2
votes
4answers
2k views

2D camera perspective projection from 3D coordinates — HOW?

I am developing a camera for a 2D game with a top-down view that has depth. It's almost a 3D camera. Basically, every object has a Z even though it is in 2D, and similarly to parallax layers their ...
2
votes
1answer
353 views

Shader issues when creating projection using CreateOrthographicOffCenter instead of CreateOrthographic

Pre. Having these matrix transformations: var scale = Matrix.CreateScale(50f); var eye = new Vector3(0, 0, 10.0f); var view = Matrix.CreateLookAt(eye, Vector3.Zero, Vector3.Up); var projection = ...
2
votes
0answers
99 views

Unproject considering parallax depth

How can I take screen coordinates (or alternatively world coordinates on the 'primary' parallax plane) and find out what world coordinates they translate into when taking parallax depth into account? ...
2
votes
0answers
104 views

Stereo 3D: drawing 2D elements at apparent screen depth

I'm developing an application making use of DirectX11's stereoscopic features. At such I am not relying on nVidia's automatic implementation. That means I have to replicate a way to render 2d elements ...
2
votes
0answers
64 views

uniform z slices in clip-space

1) Context I'm using a regular OpenGL perspective projection matrix created with GLM (glm::perspective) and taking the inverse (glm::inverse) to transform clip-space back into view space (and world ...
1
vote
3answers
185 views

Orthographic Projection with variable FOV

We are building agame with orthographic view. The problem we face is the fact that with different resolution you can see different area of the game world. E.g. if you have higher resolution you can ...
1
vote
2answers
259 views

What is the camera direction vector for an isometric view?

What values correspond to a 3D vector for screen-normal from within an isometric game? It needs to be in game coordinates. It is a standard isometric where tiles are rotated 45 degrees and half ...
1
vote
1answer
60 views

Why are there different ways of building projection matrices?

Matrix.PerspectiveFovLH documentation page says that this method uses the following formula to build a perspective projection matrix. [w, 0, 0, 0] [0, h, 0, 0] [0, 0, zFar/(zFar - zNear), 1] [0, 0, ...
1
vote
1answer
506 views

How to do geometric projection shadows?

I have decided that since my game world is mostly flat I don't need better shadows than geometric projections - at least for now. The only problem is I don't even know how to do those properly - that ...