Add world-to-screen example (#138)

Author: aglitchman

render/world_to_screen/assets/SourceSansPro-Semibold.ttf

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+#version 140
+
+// Inputs should match the vertex shader's outputs.
+in vec2 var_texcoord0;
+
+// The texture to sample.
+uniform lowp sampler2D texture0;
+
+// The final color of the fragment.
+out lowp vec4 final_color;
+
+uniform fs_uniforms
+{
+    mediump vec4 tint;
+};
+
+void main()
+{
+    // Pre-multiply alpha since all runtime textures already are
+    vec4 tint_pm = vec4(tint.xyz * tint.w, tint.w);
+
+    // Sample the texture at the fragment's texture coordinates.
+    vec4 color = texture(texture0, var_texcoord0.xy) * tint_pm;
+
+    // Output the sampled color.
+    final_color = color;
+}

render/world_to_screen/assets/materials/unlit.fp

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+name: "unlit"
+tags: "model"
+vertex_program: "/assets/materials/unlit.vp"
+fragment_program: "/assets/materials/unlit.fp"
+vertex_space: VERTEX_SPACE_LOCAL
+vertex_constants {
+  name: "mtx_view"
+  type: CONSTANT_TYPE_VIEW
+}
+vertex_constants {
+  name: "mtx_proj"
+  type: CONSTANT_TYPE_PROJECTION
+}
+fragment_constants {
+  name: "tint"
+  type: CONSTANT_TYPE_USER
+  value {
+    x: 1.0
+    y: 1.0
+    z: 1.0
+    w: 1.0
+  }
+}
+samplers {
+  name: "texture0"
+  wrap_u: WRAP_MODE_CLAMP_TO_EDGE
+  wrap_v: WRAP_MODE_CLAMP_TO_EDGE
+  filter_min: FILTER_MODE_MIN_LINEAR
+  filter_mag: FILTER_MODE_MAG_LINEAR
+  max_anisotropy: 0.0
+}

render/world_to_screen/assets/materials/unlit.material

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+#version 140
+
+// The model's vertex position and texture coordinates.
+in vec4 position;
+in vec2 texcoord0;
+
+// The model's world matrix.
+in mat4 mtx_world;
+
+// The projection and view matrices.
+uniform general_vp
+{
+    mat4 mtx_view;
+    mat4 mtx_proj;
+};
+
+// The output of a vertex shader are passed to the fragment shader.
+// The texture coordinates of the vertex.
+out vec2 var_texcoord0;
+
+void main()
+{
+    // Pass the texture coordinates to the fragment shader.
+    var_texcoord0 = texcoord0;
+
+    // Transform the vertex position to clip space.
+    gl_Position = mtx_proj * mtx_view * mtx_world * vec4(position.xyz, 1.0);
+}

render/world_to_screen/assets/materials/unlit.vp

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+	
+
+	Graveyard Kit (5.0)
+
+	Created/distributed by Kenney (www.kenney.nl)
+	Creation date: 17-10-2025 11:00
+	
+			------------------------------
+
+	License: (Creative Commons Zero, CC0)
+	http://creativecommons.org/publicdomain/zero/1.0/
+
+	You can use this content for personal, educational, and commercial purposes.
+
+	Support by crediting 'Kenney' or 'www.kenney.nl' (this is not a requirement)
+
+			------------------------------
+
+	• Website : www.kenney.nl
+	• Donate  : www.kenney.nl/donate
+
+	• Patreon : patreon.com/kenney
+	
+	Follow on social media for updates:
+
+	• Twitter:	 twitter.com/KenneyNL
+	• BlueSky:	 kenney.bsky.social
+	• Instagram: instagram.com/kenney_nl

render/world_to_screen/assets/models/License.txt

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+font: "/assets/SourceSansPro-Semibold.ttf"
+material: "/builtins/fonts/font.material"
+size: 48
+outline_alpha: 0.0
+outline_width: 0.0

render/world_to_screen/assets/models/character-ghost.glb

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+---
+tags: render
+title: World to Screen
+brief: This example demonstrates how to convert 3D world coordinates to 2D screen coordinates using camera transformations.
+author: Artsiom Trubchyk
+scripts: player.script
+thumbnail: thumbnail.png
+---
+
+This example shows how to convert world positions to screen coordinates for UI positioning. It features:
+
+* A `world_to_screen()` function that transforms 3D world positions to 2D screen coordinates using the camera's view and projection matrices.
+* A ghost character that rotates around a crypt in 3D space while floating up and down.
+* A player name label in the GUI that follows the character's world position by converting it to screen coordinates.
+* Demonstrates practical use of world-to-screen conversion for positioning UI elements relative to 3D objects.