{"id":19867481,"url":"https://github.com/erkaman/planar_proj_shadows","last_synced_at":"2025-10-28T10:04:28.948Z","repository":{"id":141383067,"uuid":"84645757","full_name":"Erkaman/planar_proj_shadows","owner":"Erkaman","description":"Demo of Planar Projected Shadows in regl","archived":false,"fork":false,"pushed_at":"2017-03-11T20:12:30.000Z","size":171,"stargazers_count":34,"open_issues_count":0,"forks_count":7,"subscribers_count":3,"default_branch":"gh-pages","last_synced_at":"2025-04-06T23:13:58.178Z","etag":null,"topics":["demo","matrix","opengl","regl","shadow","shadows","webgl"],"latest_commit_sha":null,"homepage":"https://erkaman.github.io/planar_proj_shadows/planar_proj_shadows.html","language":"JavaScript","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"mit","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/Erkaman.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2017-03-11T11:39:35.000Z","updated_at":"2024-12-29T06:14:50.000Z","dependencies_parsed_at":null,"dependency_job_id":"0ba9942b-09f8-4d8e-9004-26644cd7fae0","html_url":"https://github.com/Erkaman/planar_proj_shadows","commit_stats":null,"previous_names":[],"tags_count":0,"template":false,"template_full_name":null,"repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/Erkaman%2Fplanar_proj_shadows","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/Erkaman%2Fplanar_proj_shadows/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/Erkaman%2Fplanar_proj_shadows/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/Erkaman%2Fplanar_proj_shadows/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/Erkaman","download_url":"https://codeload.github.com/Erkaman/planar_proj_shadows/tar.gz/refs/heads/gh-pages","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":251998254,"owners_count":21677960,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["demo","matrix","opengl","regl","shadow","shadows","webgl"],"created_at":"2024-11-12T15:29:27.398Z","updated_at":"2025-10-28T10:04:23.909Z","avatar_url":"https://github.com/Erkaman.png","language":"JavaScript","funding_links":[],"categories":[],"sub_categories":[],"readme":"# planar_proj_shadows\n\nDemo of Planar Projected Shadows implemented with [regl](https://github.com/mikolalysenko/regl).\n\n![](img.jpg)\n\n[Demo here](https://erkaman.github.io/planar_proj_shadows/planar_proj_shadows.html)\n\n# Implementation Details\n\nThis is an implementation of Planar Projected Shadows, described in\nthe excellent book [Real-Time\nShadows](https://www.amazon.com/Real-Time-Shadows-Elmar-Eisemann/dp/1568814380).\n\nBasically, if we only want a plane to receive shadows, we do not need\nany Shadow Maps or Shadow Volumes. Instead, we simply define a\nprojection matrix *P* that project onto that plane. To then render the\nshadows, we render the shadow casting geometry, but instead of\nrendering them normally, (in vertex shader)we project them onto the plane using the\nmatrix *P*, and(in fragment shader) we render the geometry in black.\n\nBut note that the trick only works when casting shadows onto a plane.\n\n# Build\n\nFirst install all dependencies by doing\n\n```bash\nnpm install\n```\n\nTo then run the demo, do\n\n```bash\nnpm run start\n```\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Ferkaman%2Fplanar_proj_shadows","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Ferkaman%2Fplanar_proj_shadows","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Ferkaman%2Fplanar_proj_shadows/lists"}