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Reconfigure how sampling is done so that we do it in 16x16 chunks

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This commit is contained in:
Eryn Wells 2018-10-27 10:14:23 -07:00
parent af3031ece6
commit a14943c42f
3 changed files with 48 additions and 20 deletions
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30
MetaballsKit/Shaders/MarchingSquares.metal
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@ -45,6 +45,11 @@ samplingKernel(constant MarchingSquaresParameters &parameters [[buffer(0)]],
device float *samples [[buffer(2)]],
uint2 position [[thread_position_in_grid]])
{
if (position.x >= parameters.gridSize.x || position.y >= parameters.gridSize.y)
{
return;
}
// Find the midpoint of this grid cell.
const float2 point = float2(position.x * parameters.cellSize.x + (parameters.cellSize.x / 2.0),
position.y * parameters.cellSize.y + (parameters.cellSize.y / 2.0));
@ -68,38 +73,43 @@ kernel void
contouringKernel(constant MarchingSquaresParameters &parameters [[buffer(0)]],
constant float *samples [[buffer(1)]],
device ushort *contourIndexes [[buffer(2)]],
uint position [[thread_position_in_grid]])
uint2 position [[thread_position_in_grid]])
{
if (position.x >= (parameters.gridSize.x - 1) || position.y >= (parameters.gridSize.y - 1)) {
return;
}
// Calculate an index based on the samples at the four points around this cell.
// If the point is above the threshold, adjust the value accordingly.
// d--c 8--4
// | | -> | |
// a--b 1--2
uint a = position + parameters.gridSize.x;
uint b = position + parameters.gridSize.x + 1;
uint c = position + 1;
uint d = position;
uint rowSize = parameters.gridSize.x - 1;
uint d = position.y * rowSize + position.x;
uint c = d + 1;
uint b = d + rowSize + 1;
uint a = d + rowSize;
uint index = (samples[d] >= 1.0 ? 0b1000 : 0) +
(samples[c] >= 1.0 ? 0b0100 : 0) +
(samples[b] >= 1.0 ? 0b0010 : 0) +
(samples[a] >= 1.0 ? 0b0001 : 0);
contourIndexes[position] = index;
contourIndexes[d] = index;
}
vertex RasterizerData
gridVertexShader(constant Vertex *vertexes [[buffer(0)]],
constant Rect *rects [[buffer(1)]],
constant Rect *cells [[buffer(1)]],
constant RenderParameters &renderParameters [[buffer(2)]],
uint vid [[vertex_id]],
uint instid [[instance_id]])
{
Vertex v = vertexes[vid];
Rect rect = rects[instid];
Rect cell = cells[instid];
RasterizerData out;
out.position = renderParameters.projection * rect.transform * float4(v.position.xy, 0, 1);
out.color = rect.color;
out.position = renderParameters.projection * cell.transform * float4(v.position.xy, 0, 1);
out.color = cell.color;
out.textureCoordinate = v.textureCoordinate;
out.instance = instid;
return out;