Getting textures to always point at the screen?

[Kirado]

Hi, is it possible to get a texture to point/face the screen at all times using a GLSL shader? Any advice on how I would go about doing this?

[Lord crc]

Sounds to me like you want to read up on billboarding.

Random link: http://www.lighthouse3d.com/opengl/billboarding/

[-NiCo-]

If you want to texture small particles you may also want to take a look at point sprites (http://www.opengl.org/registry/specs/ARB/point_sprite.txt).

[Kirado]

thanks for the replies. I want to have the texture map use screen co-orindates. ie. the texture bill boards but not the the 3d object.

[sqrt[-1]]

Then do this in the vertex shader




varying vec4 projectSpace;

void main(){

// Calculate the output position and projection space lookup
projectSpace = gl_ModelViewProjectionMatrix * gl_Vertex;
gl_Position = projectSpace;
projectSpace.xy = (projectSpace.xy + vec2(projectSpace.w)) * 0.5;




And this in the fragment shader:



varying vec4 projectSpace;
uniform sampler2D TextureBitmap;

void main(){

// Look texture in screen space
vec4 tex = texture2DProj(TextureBitmap, projectSpace);



You can scale the texture coordinates in the vertex shader to suit your needs. (by default the texture will be stretched over the screen)

[Kirado]

wow thanks for your help! awesome.. will try it out ;-)

[Kirado]

yeah that code worked really well thanks again