Questions tagged [projection]

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(XNA) Pseudo-3D Buildings/Hills (like Road Rash)

So I was doing a pseudo-3d game in FNA (XNA) like roadrash or outrunners. The road is built from quads using 'UserIndexedPrimitives' and 'BasicEffect' which are calculated using pseudo-3d perspective ...
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1answer
41 views

Reversing plane projection texture mapping algorithm

I found this algorithm in some old codebase, it takes two triangles from a mesh ABC and PMN, where ABC is the triangle that will be rendered and PMN is an extra triangle that is only used to generate ...
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34 views

Unity custom camera projection only working in scene editor

I've found this article on Gamasutra on a custom camera projection to make 3D look more 2D and decided to implement it to make some gameplay tests. I had to make some changes to make it work on URP(on ...
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1answer
97 views

Can we flip znear and zfar so that positive z values increase away from the viewer?

I am confused about the projection matrix in OpenGL. i have a habit of writing the code as follows. ...
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1answer
2k views

Deproject Screen To World Coordinates (Unreal Engine 4.15)

I am working on a small game in Unreal Engine 4.15 using blueprints only and encountered a behaviour I don't understand. The game is based on the Top Down Example. As I'd like to teleport an actor ...
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1answer
76 views

Tiles on sphere - check visibility

I have a sphere with tiles. I need to heck if tile is visible or not. See the image. Tiles are red squares, "screen" is represented by yellow quad. Currently, I calculate coordinates of tile in ...
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3answers
852 views

How to render top-down perspective in a tile-based RPG?

My question is specifically about the type of perspective that GBA Pokemon games like Fire Red/Leaf Green have: I'm not sure of the correct terms for what I'm trying to achieve. I am using SDL2 and ...
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2answers
83 views

How to render a field of view of over 180 degrees?

In most 3D renderings, a view frustum is used. This has the problem, that things get stretched out towards the edges. At "normal" fov (field of view) of about 60 degrees, the effect is not ...
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2answers
676 views

Is a dynamic enviroment map using pincushion curvilinear perspective projection possible?

I'm wondering if it is possible to generate a dynamic spherical environment map using a single frame render using a pincushion curvilinear perspective projection matrix (phew, that's a mouthful)? I'...
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33 views

Game Maker - Raycasting from camera in orthographic projection

I have been trying to figure out how to click on 3D objects in Game Maker Studio 2. I am using an orthographic projection. I know the basic idea is to calculate a ray that comes from the camera ...
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35 views

Does Unity provide access to a camera's Viewport Rect in a shader?

If I, for example, set a camera's Viewport Rect to W:0.5 H:0.5, is there some way to access that in a shader? Is there some way to extract it from unity_CameraProjection? I thought about comparing ...
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1answer
144 views

Why when I do an isometric projection do I get a “dimmetric” view?

First of all I would like to apologize for my poor English. It is not my native language. I have some doubts about isometric projection that perhaps I do not know how to describe them and I would ...
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25 views

Projecting Coordinates from one Space into another, but with “twisting”

i'm trying to generate a decal mesh kinda like this: http://blog.wolfire.com/2009/06/how-to-project-decals/ but instead of projecting the decal with a box, i need to project it with a sort of ...
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1answer
85 views

Perspective projection and ultrawide resolution

The problem I'm going to describe did not occur to me until very recently, when I got a super ultra-wide monitor (32:9 aspect ratio) and tried playing videogames on it. TL;DR: the scenery is ...
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0answers
70 views

How to convert screen to world coordinates while using gluLookAt / gluPerspective or similar matrix transforms?

I am just starting an adventure in looking under the hood of graphics for a game project I've been working on for a while, and I could use some guidance. I am using Python/Kivy (though that is not ...
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27 views

Libnoise bounding box - from spherical to planar

I'm trying to convert a bounding box inside a spherical map (equirectangular image as a result of Libnoise/c++) into a planar projection, but I can't find the correct algorithm for it and I'm not good ...
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22 views

Map an equirectangular square slice inside cubemap

I'm trying to map a square slice of an equirectangular image inside a cubemap with 6 faces, without distortion. The point is that I'm dealing with huge array sizes if I try to project the whole ...
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39 views

Confused on graphics rendering

Implementing a viewport is just a rectangular space on the back buffer usually a 2d texture set to the size of the client window that we render to. However in direct3d when we describe the viewport ...
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0answers
472 views

Control frustum near and far clip plane sizes in a Projection Matrix

I'm trying to achieve a dolly zoom effect. My first try was the obvious one, the original "zoom in & dolly out" technique, which works nicely. Except that there are cases which this is not ...
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0answers
215 views

How to set the camera projectionmatrix so that it's 4 rays always exactly hit the corners of a defined plane?

I have a camera, and I have a plane. The plane has 4 corner points. I need to find out how to change the projection-matrix of the camera so that the projection-rays of the camera always hit the ...
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1answer
534 views

Greiner-Hormann clipping problem

I have a set of planar polygons in 3D space defined by their vertices in counterclockwise order. Let's define the 'positive face' as being the face of the 3D polygon such as when observed, the ...
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2answers
105 views

z ordering in directx11

Hi recently i am trying to implement z ordering system into my directx framework. So every object will have z order property(int), and this value will have higher priority than depth checking for ...
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1answer
315 views

2D HUD overlay drawing based on 3D coordinates and camera azimuth and elevation

Assume you have the 3d coordinates of the player and another unit N as well as the azimuth and elevation of a camera always looking at the player. In the following ...
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1answer
1k views

Perspective projection with 90 degrees between X-Y axis?

I'm trying to create a game that mimics Tibia's projection style: (source: mmoginfo.com) , 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 ...
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1answer
740 views

Unity3d: Get a direction vector parallel to plane

I need to send a raycast from my camera which is parallel to the plane (Ground) and in the same direction of its forward vector (Represented by the black color vector) I cant use world space ...
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0answers
60 views

Why projection window is between -1 and 1

Is it a convetion ? What we achieve with this ? I am reading about how the perspective and orthographic matrix is getting calculated and everyone is trying to normalize the homogenous coordinates to [...
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1answer
78 views

What is the alternative (new) 3d projection called that solves the stretching / zooming at sides of monitor?

I understand about camera's and projections etc, such that we have distortion and zooming when at the sides of the screen (exacerbated on 21:9 monitors), however a few years ago, in a Unity forum ...
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1answer
26 views

How can spotlights be implemented with a perspective projection?

I was reading Shadow Mapping with Directional Lights and noted that spotlights are implemented by rendering with the perspective projection, stating that the spotlight worked just like the camera. ...
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1answer
293 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 ...
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2answers
16k 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 axes)...
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1answer
43 views

Z rotation matrix inverting object

I'm currently creating a 3d game where I need to rotate shapes. To do se, I created a rotation matrix for each axis, X, Y and Z. X and Y are giving me expected results, but not Z who kind of "inverts ...
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1answer
860 views

3d isometric projection matrix?

I have 3d vectors that I want to project as 2d vectors to draw my shapes. I got a 3d vector cameraPosition, a 3d vector cameraDirection, a float renderDistance. I need to create an orthogonal / ...
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1answer
182 views

OpenGL orthographic projection rendering quarter of screen

I'm trying to set up an orthographic projection so I can draw a rectangle using screen coordinates, but even if I draw a rectangle using the width/height of the window, it only fills a quarter of the ...
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3answers
335 views

Project rendering onto a polygon in the scene

I have a function that renders a simple OpenGL scene. I want to display this scene on a polygon within another scene, without the function having to know about it. For example, to display the scene on ...
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0answers
74 views

Perspective projection matrix with a non-orthogonal near plane

I'm trying to figure out a way to provide such a perspective projection matrix to a shader that the "near" plane wouldn't necessarily be orthogonal to the camera vector. More specifically, I'm ...
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33 views

Camera LookAt position with fixed screen position

I have a perspective "lookAt-type" camera. I'm trying to compute specific focus point of the camera, which should be placed in the middle of the screen: I also have a custom 3d point in world space, ...
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1answer
912 views

Difference between two perspective projection representations

When researching perspective projections on the web, I've come across two different representations. One is unrelated to OpenGL and the other is strictly associated with it. What is the relation of ...
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1answer
1k 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, ...
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52 views

Why does this work in the fragment shader but not in the vertex shader?

I'm doing some model view and projection transforms in the vertex shader and I want to determine whether the current vertex will end up on the viewport or not. After searching a bit I found that ...
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2answers
1k 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.
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3answers
308 views

Figuring out if two objects overlap on screen

I want to figure out if 2 3D models overlap on screen. My general idea is: Compute the bounding box of each model Transform the bounding box to the View Volume using the ViewProjection matrix Check ...
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1answer
523 views

Project 360 video on the inside of a iso sphere / polygon sphere

I'm creating a game in Unity. I have a iso sphere or polygon sphere, and I want to project a 360 video on the inside of the polygon sphere. I've learned thow to put a 360 video on the inside of a ...
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1answer
354 views

Scanline filling of polygons that share edges and vertices

In the image below (a perspective projection of an icosahedron), the scanline (red) intersects that vertex at the top. In an icosahedron each edge belongs to two triangles. From edge a, only one ...
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2answers
124 views

Custom Camera View Fustrum in Unity

Is it possible in Unity to make some sort of bounding box (with a running application) within the current viewpoint of the actual screen? Let me explain: I'm working on a project which uses a ...
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0answers
455 views

2.5D UI, perspecitve view, distort objects by angle but not position

Instead of thousand words, a few pictures to explain what I want to achieve How do I get the merit of UI objects rotation in perspective projection, but ignore the position of an object(as in Overlay ...
2
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2answers
97 views

How to project textures onto an animated model?

I'm trying to figure out exactly how to project textures onto an animated model. I've taken a look at L4D2's wound's white paper. But their method doesn't exactly explain how they went about this. I'...
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3answers
7k 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: Below is a screenshot of Age of Empires II. How would you describe the "perspective"? Is it also a 2D sprite game? "...
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2answers
253 views

How can I draw the “cone of view” of a camera in a flat 2D minimap?

I have a 3D world with some model in it (the XZ-plane grid, some gray boxes and a red box). In the upper-left corner I'm trying to draw a minimap that should represents the whole world in 2D (flat). ...
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0answers
693 views

Screen-space shadows?

Is there such a thing as screen-space shadows? I know that most shadow projection comes from rendering the world from the viewpoint of the light source, projecting the shadows onto a large square ...
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0answers
147 views

How to implement a pannini projection in opengl?

I have read about the pannini projection, which involves (I think) projecting a scene onto a cyclinder instead of a rectangle. How can I implement this projection in a vertex shader? Blinky is using ...

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