public unsafe void Execute(int index)
{
RayDDAContext rayContext = inRays[index];
SegmentContext *segmentContext = rayContext.segment;
// TODO change the DDA ray setup so that we can do an intersection test with the world to find the first position instead of stepping to it
RayContinuation cont = new RayContinuation
{
segment = rayContext.segment,
ddaRay = rayContext.ddaRay,
planeRayIndex = rayContext.planeRayIndex,
rayColumn = segmentContext->activeRayBufferFull.GetRayColumn(rayContext.planeRayIndex + segmentContext->segmentRayIndexOffset),
lod = 0,
};
World *world = drawContext.worldLODs;
float farClip = drawContext.camera.FarClip;
float lodMax = drawContext.camera.LODDistances[0];
if (!World.REPEAT_WORLD)
{
// with a non-repeating world, we want to start inside the first grid position that is inside of the world
// this means we can simply stop the ray later on if it runs outside of the world
// (plus we know there's possible a lot of air out there)
int2 dimensions = world->Dimensions.xz;
int2 startPos = cont.ddaRay.Position;
if (any(startPos < 0 | startPos >= dimensions))
{
// so the start is outside of the limited world
if (cont.ddaRay.StepToWorldIntersection(dimensions))
{
while (cont.ddaRay.IntersectionDistances.x >= lodMax)
{
cont.ddaRay.NextLOD(1 << cont.lod);
cont.lod++;
world++;
lodMax = drawContext.camera.LODDistances[cont.lod];
}
if (cont.ddaRay.IsBeyondFarClip(farClip))
{
WriteSkyboxFull(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, cont.rayColumn);
}
else
{
outRays.AddNoResize(cont);
}
}
else
{
WriteSkyboxFull(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, cont.rayColumn);
}
return;
}
}
outRays.AddNoResize(cont);
}
unsafe static void ExecuteRay(RayContinuation rayContext, ref DrawContext drawContext, int ITERATION_DIRECTION)
{
SegmentContext *segmentContext = rayContext.segment;
int planeRayIndex = rayContext.planeRayIndex;
SegmentDDAData ray = rayContext.ddaRay;
ColorARGB32 * rayColumn = rayContext.rayColumn;
int lod = rayContext.lod;
int voxelScale = 1 << lod;
World *world = drawContext.worldLODs + lod;
float farClip = drawContext.camera.FarClip;
World.RLEColumn worldColumn = default;
float lodMax = drawContext.camera.LODDistances[lod];
byte *seenPixelCache = stackalloc byte[segmentContext->seenPixelCacheLength]; // turns out, stackalloc is zero-initialized with burst (for now?)
int nextFreePixelMin = segmentContext->originalNextFreePixelMin;
int nextFreePixelMax = segmentContext->originalNextFreePixelMax;
float worldMaxY = world->DimensionY;
float cameraPosYNormalized = drawContext.camera.PositionY / worldMaxY;
// small offset to the frustums to prevent have a division by zero in the clipping algorithm
float frustumBoundsMin = nextFreePixelMin - 0.501f;
float frustumBoundsMax = nextFreePixelMax + 0.501f;
float frustumDirMaxWorld = float.Epsilon;
float frustumDirMinWorld = float.Epsilon;
SetupProjectedPlaneParams(
ref drawContext.camera,
ref ray,
worldMaxY,
voxelScale,
drawContext.screen,
rayContext.segment->axisMappedToY,
out float3 planeStartBottomProjected,
out float3 planeStartTopProjected,
out float3 planeRayDirectionProjected
);
while (true)
{
// check whether we're at the end of the LOD
if (ray.IntersectionDistances.x >= lodMax)
{
ray.NextLOD(voxelScale);
lod++;
voxelScale *= 2;
world++;
lodMax = drawContext.camera.LODDistances[lod];
}
int columnRuns = world->GetVoxelColumn(ray.Position, ref worldColumn);
if (columnRuns == -1)
{
// out of world bounds
WriteSkybox(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, rayColumn, seenPixelCache);
return;
}
if (columnRuns == 0)
{
if (ray.Step(farClip))
{
break;
}
continue;
}
float worldBoundsMin = 0f;
float worldBoundsMax = worldMaxY;
if (frustumDirMaxWorld != float.Epsilon)
{
float distTop = select(ray.IntersectionDistances.x, ray.IntersectionDistances.y, frustumDirMaxWorld > 0f);
float distBot = select(ray.IntersectionDistances.x, ray.IntersectionDistances.y, frustumDirMinWorld < 0f);
float newMax = drawContext.camera.PositionY + frustumDirMaxWorld * distTop;
float newMin = drawContext.camera.PositionY + frustumDirMinWorld * distBot;
if (newMin > worldBoundsMax || newMax < worldBoundsMin)
{
// frustum went out of the world entirely
WriteSkybox(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, rayColumn, seenPixelCache);
return;
}
if (worldColumn.WorldMin > newMax || worldColumn.WorldMax < newMin)
{
// this column doesn't overlap the writable world bounds
if (ray.Step(farClip))
{
break;
}
continue;
}
worldBoundsMin = newMin;
worldBoundsMax = newMax;
}
// so, what we're going to do:
// create 2 lines from minY to maxY, one at the last intersection one at the next intersection
// project those to the screen, and adjust UVs with them to track how much of the world is on screen
// after frustum culling we'll know the minY and maxY visible on screen
// which we can then use to cull world RLE elements
float3 camSpaceMinLast = planeStartBottomProjected + planeRayDirectionProjected * ray.IntersectionDistances.x;
float3 camSpaceMinNext = planeStartBottomProjected + planeRayDirectionProjected * ray.IntersectionDistances.y;
float3 camSpaceMaxLast = planeStartTopProjected + planeRayDirectionProjected * ray.IntersectionDistances.x;
float3 camSpaceMaxNext = planeStartTopProjected + planeRayDirectionProjected * ray.IntersectionDistances.y;
if (ray.IntersectionDistances.x > 2f && frustumDirMaxWorld == float.Epsilon)
{
// determine the world/clip space min/max of the writable frustum
// clip the projected-world-column to fit in the writable-frustum; adjust the worldBounds accordingly
bool clippedLast = CameraData.GetWorldBoundsClippingCamSpace(
camSpaceMinLast,
camSpaceMaxLast,
frustumBoundsMin,
frustumBoundsMax,
out float clipLastMinLerp,
out float clipLastMaxLerp
);
bool clippedNext = CameraData.GetWorldBoundsClippingCamSpace(
camSpaceMinNext,
camSpaceMaxNext,
frustumBoundsMin,
frustumBoundsMax,
out float clipNextMinLerp,
out float clipNextMaxLerp
);
float camSpaceClippedMin, camSpaceClippedMax;
// from the (clipped or not) camera space positions, get the following data:
// min-max world space parts of the column visible - used to cull RLE elements early
// min-max camera space parts visible - used to adjust the writable pixel range, which can late-cull elements or cancel the ray entirely
if (clippedLast)
{
if (clippedNext)
{
WriteSkybox(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, rayColumn, seenPixelCache);
return;
}
else
{
worldBoundsMin = lerp(0f, worldMaxY, clipNextMinLerp);
worldBoundsMax = lerp(0f, worldMaxY, clipNextMaxLerp);
frustumDirMaxWorld = (worldBoundsMax - drawContext.camera.PositionY) / ray.IntersectionDistances.y;
frustumDirMinWorld = (worldBoundsMin - drawContext.camera.PositionY) / ray.IntersectionDistances.y;
float3 minClip = lerp(camSpaceMinNext, camSpaceMaxNext, clipNextMinLerp);
float3 maxClip = lerp(camSpaceMinNext, camSpaceMaxNext, clipNextMaxLerp);
camSpaceClippedMin = minClip.x / minClip.z;
camSpaceClippedMax = maxClip.x / maxClip.z;
if (camSpaceClippedMax < camSpaceClippedMin)
{
Swap(ref camSpaceClippedMin, ref camSpaceClippedMax);
}
}
}
else
{
if (clippedNext)
{
worldBoundsMin = lerp(0f, worldMaxY, clipLastMinLerp);
worldBoundsMax = lerp(0f, worldMaxY, clipLastMaxLerp);
float3 minClip = lerp(camSpaceMinLast, camSpaceMaxLast, clipLastMinLerp);
float3 maxClip = lerp(camSpaceMinLast, camSpaceMaxLast, clipLastMaxLerp);
frustumDirMaxWorld = (worldBoundsMax - drawContext.camera.PositionY) / ray.IntersectionDistances.x;
frustumDirMinWorld = (worldBoundsMin - drawContext.camera.PositionY) / ray.IntersectionDistances.x;
camSpaceClippedMin = minClip.x / minClip.z;
camSpaceClippedMax = maxClip.x / maxClip.z;
if (camSpaceClippedMax < camSpaceClippedMin)
{
Swap(ref camSpaceClippedMin, ref camSpaceClippedMax);
}
}
else
{
if (clipLastMinLerp < clipNextMinLerp)
{
worldBoundsMin = lerp(0f, worldMaxY, clipLastMinLerp);
frustumDirMinWorld = (worldBoundsMin - drawContext.camera.PositionY) / ray.IntersectionDistances.x;
}
else
{
worldBoundsMin = lerp(0f, worldMaxY, clipNextMinLerp);
frustumDirMinWorld = (worldBoundsMin - drawContext.camera.PositionY) / ray.IntersectionDistances.y;
}
if (clipLastMaxLerp > clipNextMaxLerp)
{
worldBoundsMax = lerp(0f, worldMaxY, clipLastMaxLerp);
frustumDirMaxWorld = (worldBoundsMax - drawContext.camera.PositionY) / ray.IntersectionDistances.x;
}
else
{
worldBoundsMax = lerp(0f, worldMaxY, clipNextMaxLerp);
frustumDirMaxWorld = (worldBoundsMax - drawContext.camera.PositionY) / ray.IntersectionDistances.y;
}
float3 minClipA = lerp(camSpaceMinLast, camSpaceMaxLast, clipLastMinLerp);
float3 maxClipA = lerp(camSpaceMinLast, camSpaceMaxLast, clipLastMaxLerp);
float3 minClipB = lerp(camSpaceMinNext, camSpaceMaxNext, clipNextMinLerp);
float3 maxClipB = lerp(camSpaceMinNext, camSpaceMaxNext, clipNextMaxLerp);
float minNext = minClipB.x / minClipB.z;
float minLast = minClipA.x / minClipA.z;
float maxNext = maxClipB.x / maxClipB.z;
float maxLast = maxClipA.x / maxClipA.z;
if (maxNext < minNext)
{
Swap(ref maxNext, ref minNext);
}
if (maxLast < minLast)
{
Swap(ref maxLast, ref minLast);
}
camSpaceClippedMin = min(minLast, minNext);
camSpaceClippedMax = max(maxLast, maxNext);
}
}
worldBoundsMin = floor(worldBoundsMin);
worldBoundsMax = ceil(worldBoundsMax);
// adjust the writable pixel range, which can late-cull elements or cancel the ray entirely
int writableMinPixel = (int)floor(camSpaceClippedMin);
int writableMaxPixel = (int)ceil(camSpaceClippedMax);
if (writableMaxPixel < nextFreePixelMin || writableMinPixel > nextFreePixelMax)
{
// world column doesn't overlap any writable pixels
WriteSkybox(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, rayColumn, seenPixelCache);
return;
}
if (writableMinPixel > nextFreePixelMin)
{
nextFreePixelMin = writableMinPixel;
while (nextFreePixelMin <= segmentContext->originalNextFreePixelMax && seenPixelCache[nextFreePixelMin] > 0)
{
nextFreePixelMin += 1;
}
}
if (writableMaxPixel < nextFreePixelMax)
{
nextFreePixelMax = writableMaxPixel;
while (nextFreePixelMax >= segmentContext->originalNextFreePixelMin && seenPixelCache[nextFreePixelMax] > 0)
{
nextFreePixelMax -= 1;
}
}
if (nextFreePixelMin > nextFreePixelMax)
{
// wrote to the last pixels on screen - further writing will run out of bounds
WriteSkybox(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, rayColumn, seenPixelCache);
return;
}
}
float elementBoundsMin;
float elementBoundsMax;
World.RLEElement *elementPointer;
if (ITERATION_DIRECTION > 0)
{
elementBoundsMin = worldMaxY;
elementBoundsMax = worldMaxY;
elementPointer = worldColumn.ElementGuardStart(ref world->Storage);
}
else
{
// reverse iteration order to render from bottom to top for correct depth results
elementBoundsMin = 0f;
elementBoundsMax = 0f;
elementPointer = worldColumn.ElementGuardEnd(ref world->Storage);
}
ColorARGB32 *worldColumnColors = worldColumn.ColorPointer(ref world->Storage);
while (true)
{
elementPointer += ITERATION_DIRECTION;
World.RLEElement element = *elementPointer;
if (!element.IsValid)
{
break;
}
if (ITERATION_DIRECTION > 0)
{
elementBoundsMax = elementBoundsMin;
elementBoundsMin = elementBoundsMin - element.Length * voxelScale;
}
else
{
elementBoundsMin = elementBoundsMax;
elementBoundsMax = elementBoundsMin + element.Length * voxelScale;
}
if (element.IsAir)
{
continue;
}
if (elementBoundsMin > worldBoundsMax)
{
if (ITERATION_DIRECTION < 0)
{
break; // bottom of the row is above the world, and we are iterating from the bottom to the top -> done
}
else
{
continue;
}
}
if (elementBoundsMax < worldBoundsMin)
{
if (ITERATION_DIRECTION > 0)
{
break; // top of this row is below the world, and we are iterating from the top to the bottom -> done
}
else
{
continue;
}
}
// we can re-use the projected full-world-lines by just lerping the camera space positions
float portionBottom = unlerp(0f, worldMaxY, elementBoundsMin);
float portionTop = unlerp(0f, worldMaxY, elementBoundsMax);
float3 camSpaceFrontBottom = lerp(camSpaceMinLast, camSpaceMaxLast, portionBottom);
float3 camSpaceFrontTop = lerp(camSpaceMinLast, camSpaceMaxLast, portionTop);
// draw the side of the RLE elements
{
float uA = element.Length;
float uB = 0f;
// check if it's in bounds clip-wise
if (drawContext.camera.ClipHomogeneousCameraSpaceLine(ref camSpaceFrontBottom, ref camSpaceFrontTop, ref uA, ref uB))
{
float2 uvA = float2(1f, uA) / camSpaceFrontBottom.z;
float2 uvB = float2(1f, uB) / camSpaceFrontTop.z;
float2 rayBufferBoundsFloat = drawContext.camera.ProjectClippedToScreen(camSpaceFrontBottom, camSpaceFrontTop);
// flip bounds; there's multiple reasons why we could be rendering 'upside down', but we just want to iterate pixels in ascending order
if (rayBufferBoundsFloat.x > rayBufferBoundsFloat.y)
{
Swap(ref rayBufferBoundsFloat.x, ref rayBufferBoundsFloat.y);
Swap(ref uvA, ref uvB);
}
int rayBufferBoundsMin = (int)round(rayBufferBoundsFloat.x);
int rayBufferBoundsMax = (int)round(rayBufferBoundsFloat.y);
// check if the line overlaps with the area that's writable
if (rayBufferBoundsMax >= nextFreePixelMin && rayBufferBoundsMin <= nextFreePixelMax)
{
// reduce the "writable" pixel bounds if possible, and also clamp the rayBufferBounds to those pixel bounds
ReducePixelHorizon(
segmentContext->originalNextFreePixelMin,
segmentContext->originalNextFreePixelMax,
ref rayBufferBoundsMin,
ref rayBufferBoundsMax,
ref nextFreePixelMin,
ref nextFreePixelMax,
seenPixelCache,
ref frustumBoundsMin,
ref frustumBoundsMax
);
for (int y = rayBufferBoundsMin; y <= rayBufferBoundsMax; y++)
{
// only write to unseen pixels; update those values as well
if (seenPixelCache[y] == 0)
{
frustumDirMaxWorld = float.Epsilon;
seenPixelCache[y] = 1;
float l = unlerp(rayBufferBoundsFloat.x, rayBufferBoundsFloat.y, y);
float2 wu = lerp(uvA, uvB, l);
// x is lerped 1/w, y is lerped u/w
float u = wu.y / wu.x;
int colorIdx = clamp((int)floor(u), 0, element.Length - 1) + element.ColorsIndex;
rayColumn[y] = worldColumnColors[colorIdx];
}
}
if (nextFreePixelMin > nextFreePixelMax)
{
// wrote to the last pixels on screen - further writing will run out of bounds
WriteSkybox(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, rayColumn, seenPixelCache);
return;
}
}
}
}
// depending on whether the element is above/below/besides us, draw the top/bottom of the element if needed
float3 camSpaceSecondaryA;
float3 camSpaceSecondaryB;
ColorARGB32 secondaryColor;
if (portionTop < cameraPosYNormalized)
{
if (elementBoundsMax > worldBoundsMax)
{
continue; // we should draw the top, but it's outside the world bounds so no
}
secondaryColor = worldColumnColors[element.ColorsIndex + 0];
camSpaceSecondaryA = lerp(camSpaceMinNext, camSpaceMaxNext, portionTop);
camSpaceSecondaryB = camSpaceFrontTop;
}
else if (portionBottom > cameraPosYNormalized)
{
if (elementBoundsMin < worldBoundsMin)
{
continue;
}
secondaryColor = worldColumnColors[element.ColorsIndex + element.Length - 1];
camSpaceSecondaryA = lerp(camSpaceMinNext, camSpaceMaxNext, portionBottom);
camSpaceSecondaryB = camSpaceFrontBottom;
}
else
{
continue; // looking straight from the side - no need to draw either top or bottom
}
// draw the top/bottom
if (drawContext.camera.ClipHomogeneousCameraSpaceLine(ref camSpaceSecondaryA, ref camSpaceSecondaryB))
{
float2 rayBufferBoundsFloat = drawContext.camera.ProjectClippedToScreen(camSpaceSecondaryA, camSpaceSecondaryB);
rayBufferBoundsFloat = round(rayBufferBoundsFloat);
int rayBufferBoundsMin = (int)rayBufferBoundsFloat.x;
int rayBufferBoundsMax = (int)rayBufferBoundsFloat.y;
// flip bounds; there's multiple reasons why we could be rendering 'upside down', but we just want to iterate in an increasing manner
if (rayBufferBoundsMin > rayBufferBoundsMax)
{
Swap(ref rayBufferBoundsMin, ref rayBufferBoundsMax);
}
// check if the line overlaps with the area that's writable
if (rayBufferBoundsMax >= nextFreePixelMin && rayBufferBoundsMin <= nextFreePixelMax)
{
// reduce the "writable" pixel bounds if possible, and also clamp the rayBufferBounds to those pixel bounds
ReducePixelHorizon(
segmentContext->originalNextFreePixelMin,
segmentContext->originalNextFreePixelMax,
ref rayBufferBoundsMin,
ref rayBufferBoundsMax,
ref nextFreePixelMin,
ref nextFreePixelMax,
seenPixelCache,
ref frustumBoundsMin,
ref frustumBoundsMax
);
for (int y = rayBufferBoundsMin; y <= rayBufferBoundsMax; y++)
{
// only write to unseen pixels; update those values as well
if (seenPixelCache[y] == 0)
{
frustumDirMaxWorld = float.Epsilon;
seenPixelCache[y] = 1;
rayColumn[y] = secondaryColor;
}
}
if (nextFreePixelMin > nextFreePixelMax)
{
// wrote to the last pixels on screen - further writing will run out of bounds
WriteSkybox(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, rayColumn, seenPixelCache);
return;
}
}
}
}
if (ray.Step(farClip))
{
break;
}
}
// reached far clip
WriteSkybox(segmentContext->originalNextFreePixelMin, segmentContext->originalNextFreePixelMax, rayColumn, seenPixelCache);
}