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Merge pull request #2160 from clayjohn/world_matrix_uniform

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Clarified use of WORLD_MATRIX in CanvasItem Shaders
This commit is contained in:
Rémi Verschelde
2019-01-26 20:51:13 +01:00
committed by GitHub
parent e76728850f 2522a78f60
commit 4f95bdba6e
1 changed files with 25 additions and 2 deletions
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27
tutorials/shading/shading_reference/canvas_item_shader.rst
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@@ -59,6 +59,29 @@ it manually with the following code:
VERTEX = (EXTRA_MATRIX * (WORLD_MATRIX * vec4(VERTEX, 0.0, 1.0))).xy;
}
.. note:: ``WORLD_MATRIX`` is actually a modelview matrix. It takes input in local space and transforms it
into view space.
In order to get the world space coordinates of a vertex, you have to pass in a custom uniform like so:
::
material.set_shader_param("global_transform", get_global_transform())
Then, in your vertex shader:
.. code-block:: glsl
uniform mat4 global_transform;
varying vec2 world_position;
void vertex(){
world_position = (global_transform * vec4(VERTEX, 0.0, 1.0)).xy;
}
``world_position`` can then be used in either the vertex or fragment functions.
Other built-ins, such as UV and COLOR, are also passed through to the fragment function if not modified.
For instancing, the INSTANCE_CUSTOM variable contains the instance custom data. When using particles, this information
@@ -71,11 +94,11 @@ is usually:
+--------------------------------+----------------------------------------------------------------+
| Built-in | Description |
+================================+================================================================+
| in mat4 **WORLD_MATRIX** | Image to World transform. |
| in mat4 **WORLD_MATRIX** | Image space to view space transform. |
+--------------------------------+----------------------------------------------------------------+
| in mat4 **EXTRA_MATRIX** | Extra transform. |
+--------------------------------+----------------------------------------------------------------+
| in mat4 **PROJECTION_MATRIX** | World to view transform. |
| in mat4 **PROJECTION_MATRIX** | View space to clip space transform. |
+--------------------------------+----------------------------------------------------------------+
| in float **TIME** | Global time, in seconds. |
+--------------------------------+----------------------------------------------------------------+