galaxy-game/client/world/hit_test.go

package world

import (
	"image/color"
	"testing"

	"github.com/stretchr/testify/require"
)

func TestHitTest_ReturnsBestByPriorityAndAllHits(t *testing.T) {
	t.Parallel()

	w := NewWorld(10, 10)

	// Build index once renderer state is initialized.
	params := RenderParams{
		ViewportWidthPx:  100,
		ViewportHeightPx: 100,
		MarginXPx:        0,
		MarginYPx:        0,
		CameraXWorldFp:   5 * SCALE,
		CameraYWorldFp:   5 * SCALE,
		CameraZoom:       1.0,
	}
	w.IndexOnViewportChange(params.ViewportWidthPx, params.ViewportHeightPx, params.CameraZoom)

	// Add overlapping objects near center.
	idLine, err := w.AddLine(4.5, 5.0, 5.5, 5.0, LineWithPriority(100))
	require.NoError(t, err)

	idCircle, err := w.AddCircle(5.0, 5.0, 1.0, CircleWithPriority(300))
	require.NoError(t, err)

	idPoint, err := w.AddPoint(5.0, 5.0, PointWithPriority(200))
	require.NoError(t, err)

	// Force index rebuild from last state (Add already does it, but keep explicit).
	w.Reindex()

	buf := make([]Hit, 0, 8)
	hits, err := w.HitTest(buf, &params, 50, 50) // center of viewport
	require.NoError(t, err)

	// Should find all three, best first (priority desc).
	require.Len(t, hits, 3)
	require.Equal(t, idCircle, hits[0].ID)
	require.Equal(t, idPoint, hits[1].ID)
	require.Equal(t, idLine, hits[2].ID)
}

func TestHitTest_BufferTooSmall_KeepsBestHits(t *testing.T) {
	t.Parallel()

	w := NewWorld(10, 10)

	params := RenderParams{
		ViewportWidthPx:  100,
		ViewportHeightPx: 100,
		MarginXPx:        0,
		MarginYPx:        0,
		CameraXWorldFp:   5 * SCALE,
		CameraYWorldFp:   5 * SCALE,
		CameraZoom:       1.0,
	}
	w.IndexOnViewportChange(params.ViewportWidthPx, params.ViewportHeightPx, params.CameraZoom)

	_, _ = w.AddLine(4.5, 5.0, 5.5, 5.0, LineWithPriority(100))
	idCircle, _ := w.AddCircle(5.0, 5.0, 1.0, CircleWithPriority(300))
	_, _ = w.AddPoint(5.0, 5.0, PointWithPriority(200))
	w.Reindex()

	// Only room for 1 hit => must keep the best (highest priority).
	buf := make([]Hit, 0, 1)
	hits, err := w.HitTest(buf, &params, 50, 50)
	require.NoError(t, err)
	require.Len(t, hits, 1)
	require.Equal(t, idCircle, hits[0].ID)
}

func TestHitTest_NoWrap_ClampsCameraAndStillHits(t *testing.T) {
	t.Parallel()

	w := NewWorld(10, 10)

	params := RenderParams{
		ViewportWidthPx:  100,
		ViewportHeightPx: 100,
		MarginXPx:        25,
		MarginYPx:        25,
		CameraXWorldFp:   -100000, // invalid camera, should be clamped
		CameraYWorldFp:   -100000,
		CameraZoom:       1.0,
		Options:          &RenderOptions{DisableWrapScroll: true},
	}
	w.IndexOnViewportChange(params.ViewportWidthPx, params.ViewportHeightPx, params.CameraZoom)

	_, err := w.AddPoint(0.0, 0.0, PointWithPriority(100))
	require.NoError(t, err)
	w.Reindex()

	// Tap near top-left of viewport should still map to world and find the point.
	buf := make([]Hit, 0, 8)
	hits, err := w.HitTest(buf, &params, 0, 0)
	require.NoError(t, err)
	require.NotEmpty(t, hits)
}

func TestHitTest_CircleStrokeOnly_HitsNearRingNotCenter(t *testing.T) {
	t.Parallel()

	w := NewWorld(10, 10)

	params := RenderParams{
		ViewportWidthPx:  100,
		ViewportHeightPx: 100,
		MarginXPx:        0,
		MarginYPx:        0,
		CameraXWorldFp:   5 * SCALE,
		CameraYWorldFp:   5 * SCALE,
		CameraZoom:       1.0,
	}
	w.IndexOnViewportChange(params.ViewportWidthPx, params.ViewportHeightPx, params.CameraZoom)

	// Stroke-only circle: FillColor alpha=0 => ring mode.
	ov := StyleOverride{
		FillColor:   color.RGBA{A: 0},
		StrokeColor: color.RGBA{A: 255},
	}
	strokeStyle := w.AddStyleCircle(ov)

	_, err := w.AddCircle(5.0, 5.0, 2.0,
		CircleWithStyleID(strokeStyle),
		CircleWithPriority(100),
	)
	require.NoError(t, err)

	w.Reindex()

	buf := make([]Hit, 0, 8)

	// Center must NOT hit.
	hits, err := w.HitTest(buf, &params, 50, 50)
	require.NoError(t, err)
	require.Empty(t, hits)

	// Near ring should hit. For small circles we use a minimum visible ring radius (3px).
	// So tapping at +3px from center should be within ring+slop.
	hits, err = w.HitTest(buf, &params, 50+3, 50)
	require.NoError(t, err)
	require.NotEmpty(t, hits)
	require.Equal(t, KindCircle, hits[0].Kind)
}

func TestHitTest_CircleRadiusScale_AffectsHitArea(t *testing.T) {
	t.Parallel()

	w := NewWorld(10, 10)
	w.SetTheme(DefaultTheme{}) // filled circles by default in our defaults
	w.IndexOnViewportChange(100, 100, 1.0)

	// raw radius=2 units, centered at (5,5)
	_, err := w.AddCircle(5, 5, 2)
	require.NoError(t, err)

	// scale=2 => eff radius=4
	require.NoError(t, w.SetCircleRadiusScaleFp(2*SCALE))
	w.Reindex()

	params := RenderParams{
		ViewportWidthPx:  100,
		ViewportHeightPx: 100,
		MarginXPx:        0,
		MarginYPx:        0,
		CameraXWorldFp:   5 * SCALE,
		CameraYWorldFp:   5 * SCALE,
		CameraZoom:       1.0,
	}

	// Tap at +4 px from center should hit (eff radius 4).
	buf := make([]Hit, 0, 8)
	hits, err := w.HitTest(buf, &params, 50+4, 50)
	require.NoError(t, err)
	require.NotEmpty(t, hits)
	require.Equal(t, KindCircle, hits[0].Kind)

	// Tap at +5 should typically miss (depending on slop); enforce by setting small slop via options.
	// We'll add a small-slope circle and test deterministically.
}