Easiest way to reconstruct eye space position

[Karmux]

Hi,

I'm tring to reconstruct eye space position from depth buffer, but my result doesn't look correct.

This is my current and one of the shortest implementations i found:

    float depth = texture2D(depthBuffer, texCoord).r;
    vec2 xy = texCoord * 2.0 - 1.0;
    vec4 clipPos = vec4(xy, depth, 1.0);
    // I pass inverseProjectionMatrix as uniform
    vec4 homo = inverseProjectionMatrix * clipPos;
    vec3 position = homo.xyz / homo.w;
    gl_FragColor =  vec4(position, 1.0);

(from: http://www.gamedev.net/topic/577382-...on-from-depth/)

This gives me only green-yellow-red colors and no visible 3D objects:


But the correct result should look like this (top right)?


I have tried out many examples. Some of them were too difficult and others gave also artifacts etc. If i visualize depth texture, then everything looks correct.

Can anybody see mistake in above code?

[Kopelrativ]

Why do you want to do it?

Seems it is easier and faster to provide it using a uniform?

[Karmux]

Why do you want to do it?

Seems it is easier and faster to provide it using a uniform?

The code above is a lighting pass fragment shader in deferred renderer.

GLSL version is 4.1.

[Alfonse Reinheart]

I actually bookmarked a post of mine on this forum to remind myself of how the math works.

I really ought to make a GL Wiki page out of that.

[Karmux]

I actually bookmarked a post of mine on this forum to remind myself of how the math works.

I really ought to make a GL Wiki page out of that.

Amazing! Everything is working perfectly now! Thank you so much!

[Alfonse Reinheart]

Can you post your code, so that others can benefit?

[Karmux]

Can you post your code, so that others can benefit?

Sure

in vec2 texCoord;
uniform float nearPlane;
uniform float farPlane;
uniform sampler2D depthBuffer;
uniform mat4 inverseProjectionMatrix;
 
#define ZNEAR nearPlane
#define ZFAR farPlane
#define A (ZNEAR + ZFAR)
#define B (ZNEAR - ZFAR)
#define C (2.0 * ZNEAR * ZFAR)
#define D (ndcPos.z * B)
#define ZEYE (-C / (A + D))
 
void main() {
    float depth = texture2D(depthBuffer, texCoord).r;
    vec3 ndcPos = (vec3 (texCoord, depth) - 0.5) * 2.0;
    vec4 clipPos;
    clipPos.w = -ZEYE;
    clipPos.xyz = ndcPos * clipPos.w;
    vec4 eyePos = inverseProjectionMatrix * clipPos;
    gl_FragColor =  vec4(eyePos);
}