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14
votes
1answer
2k views

What projection is this?

Could someone tell me what this projection is called? It's as if you are looking at an object from directly above it and then smear it up and left equally. Only the one dimension seems to be true ...
0
votes
0answers
30 views

Perspective projection

I'm studying Perspective projection in a computer graphics course and i'm really confused about a detail. The study material says there are 3 cases: Case 1: View plane parallel to the xy plane and ...
1
vote
1answer
27 views

Does projection take place before clipping in the rendering pipeline?

At first I thought clipping happens before projection since new vertices may be added and the output of projection is in NDC which is 2D. However after a lot of googling, I found that some ...
9
votes
4answers
186 views

How do I correctly project a point behind the camera?

I am making a 3D game in which I put an exclamation marker above points of interest. In order to find out where in the 2D screen should I put my marker, I am manually projecting the 3D point where ...
0
votes
1answer
63 views

How to draw 2d above 3d scene?

I have an OpenGL(3.3)+GLEW application. I want to draw a black vertical rectangle at the left side of the window for writing some information on it, like fps (I use GLEW function for drawing text). ...
0
votes
1answer
249 views

How do 3D games create the illusion of depth?

How do libraries like OpenGL convert three dimensional coordinates into the two dimensional pixels we see on our screens? I'm not talking about the 3DS or games that require 3D glasses, but rather the ...
0
votes
0answers
43 views

How to convert Screen-space translation into World-space translation

private void Translate(SceneMouseMoveEventArgs args) { var camera = args.Camera; origin_screenspace = camera.UnProject(_position).Xy; cursor_screenspace = new ...
0
votes
1answer
51 views

Projectile Shoot three at a time

In my game there is a bird flying and on touch it throws different artifacts projectile downwards. And these artifacts should hit the containers moving right to left on the screen. Now if user keeps ...
4
votes
2answers
351 views

How can I achieve a pseudo-3D camera effect like this?

I am trying to achieve a pseudo-3D camera effect similar to this: I have gotten the following results using a 3D camera and billboards: I am now running into the following problems: In the ...
2
votes
2answers
2k views

What is the difference between an orthographic and oblique projection?

They both seem to be a parallel projection. I know that the angles of axes of viewing differ based on the type of orthographic projection (eg, an isometric projection has equal angles for all the ...
2
votes
1answer
86 views

Why does the projection matrix transform object points into a unit cube in computer graphics?

This semester I both took a computer vision and a computer graphics seminar. But only now before the exams I realize that there seems to be a fundamental difference between projection in both topics. ...
0
votes
1answer
150 views

Distortion problem with perspective projection

For various reasons – partly educational, partly technical – I'm writing a 3D game engine from scratch, using OpenGL 3.0; aiming for Core Profile, eventually, so of course I'm using a custom matrix ...
0
votes
0answers
41 views

Perspective Projection Far Plane Not Clipping?

I've just discovered that far away objects in my world don't seem to clip like they should with a perspective projection matrix. When I fly far away from my main landscape, so that I am much more ...
0
votes
0answers
38 views

What map projection is needed to transform a shapefile into a 3D earth?

I'm looking for a way to create a 3D earth in Flash, something like the wonderful SolarSystemScope, only in my map the countries should be clickable and whatnot. To get started I've got map data from ...
2
votes
2answers
159 views

How to calculate a 3D orientation from 2D vanishing lines on an image?

Let say I have a image that represent a 3D scene. I did not have the 3D camera orientation of that scene (left, up and forward vectors) and i'd like to calculate it. On that picture, I draw the ...
0
votes
1answer
109 views

Perspective Projection - Drawing Lines

So I sort of understand the math behind projecting 3d points onto a 2d plane. It's just some simple dividing and multiplication of distances. However I can't seem to wrap my head around projecting ...
0
votes
1answer
108 views

GameObject is only rendered when it has a negative z scale

I have an orthographic camera that looks like this: I create 2d polygonal meshes that have uniform z values in their vertices. I use Camera.ViewportToWorldPoint() to map these viewpoint vertices to ...
0
votes
1answer
78 views

Scaling world - projection, view or separate matrix?

I am currently writing a simple 3D space visualisation program. Things get loaded into it from a simple XML file, which contains positions and sizes of objects in space, so you can put basically any ...
0
votes
1answer
120 views

Mesh Generation In Code [closed]

My camera looks like this: I am trying to add 2D polygons to the screen based on the percentage that they take up of a 1920x1080 pixel canvas. Therefore, I calculate this and then use ...
4
votes
1answer
149 views

How to compute point in view space from depth?

I am trying to implement do some screen space rendering but after looking over the web I still don't find answers to some doubts. First, I need to compute the point in view space from a value in the ...
0
votes
0answers
113 views

Change 2D Angle Into Isometric Angle

i Rendered My Sprite With 72 Angles In Isometric View. Rendered Frame Number 0 And Angle 0 Is When My Sprite Looking Right And And I Rendered My Sprite Every 5 Angle. In My 2D Game My Sprite Moving ...
3
votes
1answer
408 views

Mixing Perspective and Orthographic Projections?

I'm going to start with some background, so jump to my question at the bottom for the TLDR version. Problem: In a Japanese 4gamer article (english translation via Chev on Polycount) explaining some ...
2
votes
1answer
97 views

XNA: How do I match Spritebatch View/Projection Matrices with BasicEffect Matrices?

I'm rendering a bunch of 2D content using SpriteBatches to a default XNA viewport. A simple 2D camera is used to move around the scene, which generates a transformation matrix passed to each ...
2
votes
1answer
80 views

Orthogonal projections question

I'm very VERY new into the game development world and I had just some slight trouble wrapping my head around something. We were told between classes just to think about how scaling matrices can ...
0
votes
1answer
256 views

Computing Field-of-View from window dimensions

I'm looking into computing the vertical Field-of-View (FOVy) based on the projection parameters of my camera. From this source, I've found an equation that seems to work. float ...
1
vote
1answer
64 views

Rendering order for units behind objects?

Im developing a 2D game with some fake 3D effects (parallell projection). 2D-units are able to walk in front of buildings aswell as behind them, although themselves being just 2d-objects. This leads ...
4
votes
1answer
119 views

How do I deal with floating-point error given a far-away camera?

Whenever a camera is "far" away (its location is some "large" vector), trouble arises when rendering objects close to it: It is the classic precision loss from subtracting 2 floating point numbers. I ...
0
votes
1answer
150 views

How do you create a 2d world then view it in 3d?

I have been learning OpenGL for a while now and have a pretty good understanding so far. What I would like to know is if I create a 2D game in Orthographic Projection, is it possible to switch to a ...
1
vote
2answers
310 views

How to determine the visibility of a single vertex, given a viewpoint?

I have a 3D triangle mesh, and I want to know, given a viewpoint (defined by a model, view and projection matrix), if a certain vertex is visible or not. My approach was to render the mesh using ...
-3
votes
1answer
67 views

projection and matrices [closed]

Many games do just fine with two projections, that can be represented by a matrix (orthographic and linear perspective). But what about projections that can't be represented by a matrix? Can you ...
0
votes
1answer
734 views

Projective texturing and falloff

I quite understand how projective texturing works. I implemented successfully a shader for that following nvidia doc. The major problem I'm facing is that with that implementation the projector ...
21
votes
3answers
2k views

Are there 3D projections other than orthographic and perspective? [closed]

The question is pretty much in the title. Are there notable 3D projections other than orthographic and perspective that could be used in a 3D system such as OpenGL? In particular, are there any that ...
1
vote
1answer
100 views

projection / view matrix: the object is bigger than it should and depth does not affect vertices [closed]

I'm currently trying to write a C 3D software rendering engine from scratch just for fun and to have an insight on what OpenGL does behind the scene and what 90's programmers had to do on DOS. I have ...
2
votes
2answers
165 views

How do I convert screen coordinates to between -1 and 1?

I'm writing a function that allows me to click on my tiles. The origin for my tiles is the center, however, the mouse's origin is the top left. I need a way to transform my mouse coordinates into my ...
3
votes
1answer
305 views

How to achieve cavalier projection using OpenGL fixed pipeline?

I want to make a quick demo program showing a cube, or a user loaded model, rotating in screen rendered with one of three projections: perspective, isometric and cavalier. Using the fixed pipeline, ...
2
votes
1answer
536 views

How do I check why is no output on screen?

I'm using OpenGL 3.3+, and I'm trying to create an orthographic projection to draw on screen. I have the model data in a buffer: X Y 0, 0 50, 100 100, 0 And I create my Model-View-Projection ...
7
votes
2answers
960 views

What kind of projection is demonstrated in this screenshot?

I want to know what projection is used in the following game: The game is Goodgame Empire.
1
vote
2answers
620 views

What dimensions should you use for a perspective projection frustum?

What dimensions should you use for a perspective projection frustum? Initially I created a perspective matrix based on the width and height of the screen, with a calculated zNear value based on a ...
0
votes
0answers
62 views

Rasterizing euclidean planes

I'd like to visualize a BSP tree. To do this, I need to project an arbitrary euclidean plane onto a projection plane. I was thinking about calculating the intersections of the plane with the viewing ...
3
votes
1answer
2k views

Using gluUnProject to transform mouse position to world coordinates (LWJGL)?

I have a little LWJGL application and I have been trying to figure out how to successfully use the GLU.gluUnProject function in order to transform a given point on the screen (mouse position) to world ...
1
vote
1answer
630 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
198 views

Where is the error in my perspective projection implementation?

My question is not really a game development question, but since it's based on 3D programming, I thought it would fit best here. I've got a line made out of Point3D objects where the value of x, y, ...
1
vote
1answer
126 views

Why does everything appear backwards when using orthographic projection?

I may not be calculating my orthographic projection matrix properly. What can I do to ensure that my scene renders correctly when using orthographic projection? The rendering order appears to be ...
2
votes
1answer
173 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
2answers
249 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 ...
4
votes
1answer
963 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 ...
0
votes
1answer
43 views

Rotate final image with projection matrix

I'm trying to use space in my shadow (depth) maps in a more efficient way. If I could freely rotate the final image I get with projection matrix I could save a lot of pixels, but I don't know if it is ...
0
votes
2answers
415 views

OpenGL ES, orthopgraphics projection and viewport

I want to make some simple 2D game on iOS to familiarize myself with OpenGL ES. I started with Ray Wenderlich tutorial (How To Create A Simple 2D iPhone Game with OpenGL ES 2.0 and GLKit). That ...
1
vote
3answers
719 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 ...
0
votes
1answer
168 views

Perspective projection computation

I'm learning OpenGL from arcsynthesis and I don't understand something about perspective projection (http://www.arcsynthesis.org/gltut/Positioning/Tut04%20Perspective%20Projection.html). When the ...