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/**
* Translates a position (or any <code>vec3</code>) that was encoded with {@link EncodedCartesian3},
* and then provided to the shader as separate <code>high</code> and <code>low</code> bits to
* be relative to the eye. As shown in the example, the position can then be transformed in eye
* or clip coordinates using {@link czm_modelViewRelativeToEye} or {@link czm_modelViewProjectionRelativeToEye},
* respectively.
* <p>
* This technique, called GPU RTE, eliminates jittering artifacts when using large coordinates as
* described in <a href="http://blogs.agi.com/insight3d/index.php/2008/09/03/precisions-precisions/">Precisions, Precisions</a>.
* </p>
*
* @name czm_translateRelativeToEye
* @glslFunction
*
* @param {vec3} high The position's high bits.
* @param {vec3} low The position's low bits.
* @returns {vec3} The position translated to be relative to the camera's position.
*
* @example
* attribute vec3 positionHigh;
* attribute vec3 positionLow;
*
* void main()
* {
* vec4 p = czm_translateRelativeToEye(positionHigh, positionLow);
* gl_Position = czm_modelViewProjectionRelativeToEye * p;
* }
*
* @see czm_modelViewRelativeToEye
* @see czm_modelViewProjectionRelativeToEye
* @see czm_computePosition
* @see EncodedCartesian3
*/
vec4 czm_translateRelativeToEye(vec3 high, vec3 low)
{
vec3 highDifference = high - czm_encodedCameraPositionMCHigh;
vec3 lowDifference = low - czm_encodedCameraPositionMCLow;
return vec4(highDifference + lowDifference, 1.0);
}
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8 entries across 8 versions & 1 rubygems