GLSL built-in function
texture2DProjLod()
Combines projected coordinates with an explicit mip level in a vertex shader.
Syntax
vec4 texture2DProjLod(sampler2D sampler, vec3 coord, float lod)Parameters
- sampler
- Bound fixture texture
- coord
- Lookup coordinate
- lod
- Mip level; zero is full resolution
Return value
A vec4 from a 2D lookup using coordinates divided by the projection component and the explicit mip level.
Live example
Edit the code and the preview updates as you type.
What texture2DProjLod does
Combines projected coordinates with an explicit mip level in a vertex shader.
Read the preview
The vertex call uses vec3(uv,1.0), so projection currently leaves UV unchanged before the explicit LOD lookup. Change 1.0 to 2.0 and the interpolated corner colors come from the lower-left quarter of the texture.
Core call
texture2DProjLod(u_texture,vec3(uv,1.0),u_parameter*7.0).rgb;
Requires mipmaps; LOD is not a blur radius. This example executes in the vertex stage.
Experiment
In the Vertex source, set u_parameter*7.0 to 7.0. This chooses a very coarse mip at the vertices, so the quad becomes a blend of coarse samples rather than displaying sharp lettering.