public void setupSprites(SInstancedSpriteData instanceData)
{
var numElements = Math.Max(_rects.Length, _scales.Length);
_spriteSlotIdxs = instanceData.requestSlots(numElements);
for (int i = 0; i < _rects.Length; ++i)
{
instanceData.writeRect(_spriteSlotIdxs[i], _rects [i]);
}
for (int i = 0; i < _scales.Length; ++i)
{
instanceData.writeMasterScale(_spriteSlotIdxs [i], _scales [i]);
}
}
public void updateSprites(SInstancedSpriteData instanceData, ref RectangleF screenClientRect,
ref Vector3 cameraPos, ref Matrix4 camera3dView, ref Matrix4 camera3dProj)
{
float occDiskScreenAreaUsed = (float)_occDiskObj.OcclusionQueueryResult;
if (occDiskScreenAreaUsed <= 0f)
{
// hide all sprites
var nanVec = new Vector2(float.NaN);
instanceData.writePosition(_backgroundSpriteIdx, nanVec);
instanceData.writePosition(_overlaySpriteIdx, nanVec);
return;
}
var laserParams = _laser.parameters;
var beam = _laser.beam(_beamId);
float beamIntensity = _laser.envelopeIntensity * beam.periodicIntensity;
// position sprites at the beam start in screen space
Matrix4 camera3dViewProjMat = camera3dView * camera3dProj;
var beamStartScreen = OpenTKHelper.WorldToScreen(beam.startPosWorld,
ref camera3dViewProjMat, ref screenClientRect);
instanceData.writePosition(_backgroundSpriteIdx, beamStartScreen);
instanceData.writePosition(_overlaySpriteIdx, beamStartScreen);
// compute screen space needed to occupy the area where the start of the middle's crossbeam
// would be displayed
Matrix4 viewInverted = camera3dView.Inverted();
Vector3 viewRight = Vector3.Transform(Vector3.UnitX, viewInverted).Normalized();
Vector3 occRightMost = _occDiskObj.Pos + viewRight * laserParams.middleBackgroundWidth;
Vector2 occRightMostPt = OpenTKHelper.WorldToScreen(occRightMost,
ref camera3dViewProjMat, ref screenClientRect);
Vector2 occCenterPt = OpenTKHelper.WorldToScreen(_occDiskObj.Pos,
ref camera3dViewProjMat, ref screenClientRect);
float crossBeamRadiusScreenPx = Math.Abs(occRightMostPt.X - occCenterPt.X);
// write sprite size big enough to cover up the starting section of the cross beam (middle)
float scale = Math.Max(laserParams.emissionFlareScreenSizeMin, crossBeamRadiusScreenPx * 2.5f)
* beamIntensity;
instanceData.writeMasterScale(_backgroundSpriteIdx, scale * 1.2f);
instanceData.writeMasterScale(_overlaySpriteIdx, scale * 1f);
// add some variety to orientation to make the sprites look less static
instanceData.writeOrientationZ(_backgroundSpriteIdx, beamIntensity * 1f * (float)Math.PI);
instanceData.writeOrientationZ(_overlaySpriteIdx, beamIntensity * 1f * (float)Math.PI);
// color intensity: depends on the dot product between to-camera vector and beam direction;
// also depends on how of the occlusion disk area is visible
float maxScreenArea = (float)Math.PI
* laserParams.emissionOccDiskRadiusPx * laserParams.emissionOccDiskRadiusPx;
float occDiskAreaRatio = occDiskScreenAreaUsed / maxScreenArea;
//System.Console.WriteLine("occDiskAreaRatio = " + occDiskAreaRatio);
Vector3 toCamera = (cameraPos - beam.startPosWorld).Normalized();
float dot = Math.Max(0f, Vector3.Dot(toCamera, beam.directionWorld()));
//System.Console.WriteLine("dot = " + dot);
var alpha = occDiskAreaRatio * 1.2f * (float)Math.Pow(beamIntensity, 0.1) * (float)Math.Pow(dot, 0.1);
alpha = Math.Min(alpha, 1f);
// finish background color
var backgroundColor = laserParams.backgroundColor;
backgroundColor.A = alpha;
instanceData.writeColor(_backgroundSpriteIdx, backgroundColor);
// finish overlay color
var overlayColor = laserParams.overlayColor;
overlayColor.A = alpha;
instanceData.writeColor(_overlaySpriteIdx, overlayColor);
}