Quick answer: Set the SpriteFont’s sampling mode to Point for pixel-art text, use Letterbox integer scale to avoid fractional scaling, and design your source art at the correct resolution for your target viewport. Bilinear filtering on pixel-art glyphs is the single most common cause of blurry text on mobile.

Your SpriteFont looks razor-sharp in the Construct 3 editor. You export to Android, open it on a phone, and the text is a smeared mess. The letters bleed into each other and the carefully-crafted pixel grid is gone. The art is fine — the GPU is smoothing it with bilinear filtering because you left the sampling mode on the wrong setting.

Why SpriteFonts Blur on Mobile

A SpriteFont in Construct 3 is a bitmap image where each glyph occupies a fixed rectangle. When the game renders, Construct draws each glyph by sampling from the source image. The sampling mode determines how the GPU interpolates when the source and destination sizes do not match exactly.

Linear sampling (default for many object types) averages neighboring pixels, producing smooth gradients. This is great for photographs and anti-aliased text, but it destroys the sharp edges of pixel art. A 1-pixel border on a glyph becomes a 2-pixel smear.

Point sampling picks the nearest pixel without averaging. This preserves sharp edges perfectly but looks jagged on non-integer scale factors. For pixel-art SpriteFonts, Point is always the right choice.

The Fix

Step 1: Set SpriteFont sampling to Point.

Select the SpriteFont object in the layout editor. In the Properties panel, find the Sampling property and change it from Default (or Linear) to Point. This affects only this SpriteFont; other objects keep their own sampling settings.

If you have multiple SpriteFonts, set each one individually. There is no global SpriteFont sampling override.

Step 2: Use letterbox integer scale.

Open Project Properties → Fullscreen mode. The options are:

For pixel-art games, Letterbox integer scale is the gold standard. It guarantees every source pixel maps to an NxN block of screen pixels, preserving the grid perfectly. The small black bars are a fair trade for crisp text.

If you cannot accept black bars, use Letterbox scale but accept that fractional scaling will produce minor blur on Point-sampled content. In that case, design your SpriteFont at 2x resolution and let the downscale happen gracefully.

Step 3: Match source art to viewport.

If your viewport is 480×270 and your SpriteFont glyphs are 8×8 pixels, the text will be tiny on a 1080p screen unless the engine scales the canvas. If you use Point sampling with integer scale (3x), each glyph becomes 24×24 on screen — sharp and readable.

If your viewport is 1920×1080 (matching the device), no scaling happens and the SpriteFont renders at 1:1. In this case, design the font at the screen resolution and use Linear sampling — it is not pixel art at that scale.

High-DPI Devices

Modern phones have device pixel ratios of 2x or 3x. Construct 3’s “High quality” project setting renders at the device’s native resolution and then downsamples. If your SpriteFont source is 1x, the downsample blurs it. Either design the font at 2x and let the downsample sharpen naturally, or disable High quality rendering for pixel-art projects.

Testing on Real Devices

The Construct 3 preview in Chrome on desktop does not accurately represent mobile GPU sampling. Always test on a real phone. Export a test APK or use the Remote Preview feature to see the actual rendering. Check both landscape and portrait orientations — different orientations may use different scale factors.

When to Use Text Instead of SpriteFont

If your game is not pixel art, consider using the built-in Text object instead of SpriteFont. The Text object renders with the browser’s font engine and scales cleanly to any resolution without manual configuration. SpriteFonts are best reserved for pixel-art style games that need a specific bitmap look.

Understanding the issue

This bug class falls into a pattern that's worth understanding beyond the specific case. In Construct 3, the underlying behavior is shaped by how the engine layers its abstractions - the public API you call, the runtime systems that respond, and the platform-specific implementations underneath. A bug at any layer can produce symptoms that look like they originate at a different layer. Triaging effectively means recognizing which layer the symptom belongs to, even when the gameplay code is what's visible.

The specific bug described above is the kind that surfaces during integration rather than unit testing. It depends on a combination of factors: the asset configuration, the runtime state, the platform's specific behavior. In isolation, each piece looks correct; in combination, the bug emerges. This is why thorough integration testing - playing the actual game in realistic conditions - catches things that automated tests miss.

Why this happens

The triage path for this kind of bug is long. The symptom appears in gameplay, but the cause is in a different system. The reporter describes the gameplay effect; the engineer has to translate that into a hypothesis about the underlying cause. Misdirection is common.

At the engine level, the behavior comes from a deliberate design decision in Construct 3. The engine team chose a particular trade-off - usually performance versus convenience, or generality versus specificity - and that trade-off has consequences when you push against it. Understanding the trade-off is what turns 'this bug is mysterious' into 'this bug is the expected consequence of this design'.

Verifying the fix

After applying the fix, the verification step has three parts: confirm the original repro is resolved, confirm no obvious regressions in adjacent functionality, and (for shipping titles) deploy to a small player cohort first and watch the crash and report rates. Each step catches something the others miss.

Reproducibility is the prerequisite for verification. If you can't reliably reproduce the bug pre-fix, you can't reliably verify it post-fix. Spend time getting a clean reproduction before you write any fix code. The fix is fast once you understand the reproduction; the reproduction is the slow part.

Variations to watch for

There's almost always a less obvious case where the same problem applies. The reported case is the one a player hit; the related cases hide because they're rarer or affect fewer players. After fixing the reported case, search the codebase for the pattern - one fix often unlocks several.

Adjacent bugs often share a root cause. After fixing the case you've found, spend an hour searching the codebase for similar patterns. What's the same call with different arguments? The same data flow with a different entity type? The same lifecycle issue in a sibling system? Each match is a candidate for the same fix, or a related fix that prevents future bugs of the same class.

In production

In shipping builds, this issue may interact with other production-only behavior. Stripping, encryption, asset bundling, and platform-specific code paths can each modify the symptoms. When players report a related issue, capture build SHA, platform, and any feature flags - those three fields cover most of the production-only variations.

When triaging a similar issue in production, prioritize gathering data over hypothesizing causes. A player report describes a symptom; what you need is a build SHA, a session timestamp, and ideally a screen recording or session replay. With those, the bug becomes tractable. Without them, you're guessing at hypothetical reproductions that may not match what the player actually hit.

Performance considerations

If this issue manifests under high load (many actors, many particles, many network connections), profile the post-fix code path with realistic counts. The original cost was a bug; the new cost is real work, and real work has a budget.

Diagnostic approach

The diagnostic tools available depend on your engine and platform. Use the engine's native profilers and debug overlays before reaching for external tools. The native tools have context that external tools lack - they know which subsystem owns the code, which assets are loaded, and what state the engine is in.

For Construct 3-specific diagnostics, the editor's profiler is the canonical starting point. Capture a representative frame with the symptom present; compare against a frame without the symptom; the diff often points directly at the cause. If the symptom is non-deterministic, capture multiple frames and look for the pattern - the cause is usually a state transition or a specific input value rather than a continuous effect.

Tooling and ecosystem

Modern engine versions ship better tooling for this kind of issue than older versions. If you're on an older release, the diagnostic step may take significantly longer because the tools you'd want don't exist yet. Sometimes the right answer is upgrading rather than fighting through limited tooling.

Within Construct 3, the relevant diagnostic surfaces include the standard frame debugger, memory profiler, and engine-specific debug overlays. Each one shows a different facet of what's happening. The frame debugger reveals draw call ordering and state transitions; the memory profiler shows allocation patterns; the debug overlay reveals per-system state. Bugs that resist one tool usually surrender to another - the trick is knowing which tool to reach for first.

Edge cases and pitfalls

Edge cases for this class of issue often involve specific timing: the first frame after a state change, the last frame before a transition, frames where multiple subsystems update simultaneously. Reproducing these reliably is part of what makes the bug class hard to test.

When writing a regression test for this fix, focus on the boundary conditions that surfaced the original bug. Tests that exercise the happy path catch obvious regressions; tests that exercise the boundary catch the subtler regressions that look like new bugs but are really the original returning. The latter are the tests that earn their keep over the long life of the project.

Team communication

When this bug class affects multiple teams (often the case for cross-system issues), early communication prevents duplicate work. The team that owns the symptom may not own the cause. A 15-minute conversation at the start of triage often saves hours of independent investigation.

If this fix touches a system several engineers work in, a short writeup in the team's engineering channel helps. Not a full design doc - a paragraph explaining what was wrong, what's fixed, and what to watch for. Future engineers encountering similar symptoms will search for the fix; making it findable is a small investment that pays back later.

“Point sampling and integer scale are the two settings every pixel-art Construct 3 game needs. Skip either one and the art you spent months on turns to mush on the player’s phone.”

Related Issues

For broader Construct 3 mobile visual issues, see Construct 3 sprite flickering on mobile devices. For performance on mobile, see Construct 3 performance low FPS lag. For save data problems on mobile, see Construct 3 local storage data not persisting.

Test every SpriteFont on the cheapest Android phone you can find. If it looks good there, it looks good everywhere.