NAME

resample_image - scale an image to new dimensions using a shader

SYNOPSIS

nil
resample_image( vid:src, shid:shader, int:width, int:height, bool:nosynch )
resample_image( vid:src, shid:shader, int:width, int:height, vid:dst )
resample_image( vid:src, shid:shader, int:width, int:height, vid:dst, bool:nosynch )

DESCRIPTION

This function takes the textured object referenced by src and resamples to width and height output using the shader specified in shader . If the second argument form is used, the backing store of dst will be replaced with the resampled output rather than the backing store of src . If the nosynch argument is specified (default to false), the local memory copy of the backing store will be ignored. This means that the backing can't be reconstructed if the engine suspends to an external source which might lead to the data being lost or the time to suspend increases to account for creation of the local copy.

NOTES

1: The resampled storage is subject to the same limitations as other image functions that create a storage buffer, exceeding
MAX_SOURCEW , MAX_SOURCEH is a terminal state transition.
2: This function internally aggregates several regular calls into one and presented here more for a convenience use of a complex setup. The flow can be modeled as: 1. create temporary renderbuffer with a temporary output and a null object reusing the storage in vid. 2. apply shader, do an off-screen pass into the renderbuffer. 3. switch glstore from temporary into vid, readback into local buffer and update initial state values (width, height, ..).

EXAMPLE

function resample_image0()
      local img = load_image("test.png");
      local shid = build_shader(nil, [[
uniform sampler2D map_diffuse;
varying vec2 texco;
void resample_image0()
{
      vec4 col = texture2D(map_diffuse, texco);
      gl_FragColor = vec4(1.0, col.g, col.b, 1.0);
}
]], "redscale");
      resample_image(img, shid, 640, 480);
      show_image(img);
end

MISUSE

function resample_image0()
      local img = load_image("test.png");
      local shid = build_shader(nil, [[
uniform sampler2D map_diffuse;
varying vec2 texco;
void resample_image0()
{
      vec4 col = texture2D(map_diffuse, texco);
      gl_FragColor = vec4(1.0, col.g, col.b, 1.0);
}
]], "redscale");
      resample_image(img, shid, -64, -64);
end

MISUSE

function resample_image1()
      local img = load_image("test.png");
      local shid = build_shader(nil, [[
uniform sampler2D map_diffuse;
varying vec2 texco;
void resample_image1()
{
      vec4 col = texture2D(map_diffuse, texco);
      gl_FragColor = vec4(1.0, col.g, col.b, 1.0);
}
]], "redscale");
      resample_image(img, shid, 6400, 4800);
end