ntut-open-source-club/practical-tools-for-simple-design

Image Alignment Issue w/ Some PNG files

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#105 opened on Feb 11, 2024

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bughelp wanted

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Description

Problem

PNG/JPG files converted from GIF (from this website) has alignment issues when displayed on screen. However, BMP files converted with the same method doesn't have these issues.

Adding glPixelStorei(GL_UNPACK_ALIGNMENT, 1) before glTexImage2D fixes the issue with PNG/JPG files, but breaks BMP files. Also, glPixelStorei(GL_UNPACK_ALIGNMENT, 1) doesn't seems to have any affect on images that are not converted from GIFs.

Demo

PNG w/o glPixelStorei(GL_UNPACK_ALIGNMENT, 1)

image

PNG w/ glPixelStorei(GL_UNPACK_ALIGNMENT, 1)

image

BMP w/o glPixelStorei(GL_UNPACK_ALIGNMENT, 1)

image

BMP w/ glPixelStorei(GL_UNPACK_ALIGNMENT, 1)

image

Proposed Workaround

Use BMP when converting from GIFs

Contributor guide

Research direction
Investigate the pixel alignment settings for different image formats when loading textures in OpenGL.
Tech stack
cpp
Domain
game dev
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60