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Emphasize the importance of mipmaps for textureLod() in Screen-reading shaders

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This also mentions that reading the normal/roughness buffer is only
currently supported in Forward+.
This commit is contained in:
Hugo Locurcio
2023-10-26 02:25:20 +02:00
parent c1d835834d
commit 9773552257
4 changed files with 23 additions and 10 deletions
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7
tutorials/shaders/custom_postprocessing.rst
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@@ -40,8 +40,9 @@ Your scene tree will look something like this:
As of the time of writing, Godot does not support rendering to multiple
buffers at the same time. Your post-processing shader will not have access
to normals or other render passes. You only have access to the rendered
frame.
to other render passes and buffers not exposed by Godot (such as depth or
normal/roughness). You only have access to the rendered frame and buffers
exposed by Godot as samplers.
For this demo, we will use this :ref:`Sprite <class_Sprite2D>` of a sheep.
@@ -60,6 +61,8 @@ shader by `arlez80 <https://bitbucket.org/arlez80/hex-mosaic/src/master/>`_,
shader_type canvas_item;
uniform vec2 size = vec2(32.0, 28.0);
// If you intend to read from mipmaps with `textureLod()` LOD values greater than `0.0`,
// use `filter_nearest_mipmap` instead. This shader doesn't require it.
uniform sampler2D screen_texture : hint_screen_texture, repeat_disable, filter_nearest;
void fragment() {

11
tutorials/shaders/screen-reading_shaders.rst
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@@ -44,6 +44,12 @@ the third argument to ``textureLod`` and change the hint ``filter_nearest`` to
filter with mipmaps, Godot will automatically calculate the blurred texture for
you.
.. warning::
If the filter mode is not changed to a filter mode that contains ``mipmap`` in its name,
``textureLod`` with a LOD parameter greater than ``0.0`` will have the same appearance
as with the ``0.0`` LOD parameter.
Screen texture example
~~~~~~~~~~~~~~~~~~~~~~
@@ -163,6 +169,11 @@ The following code retrieves the 3D position below the pixel being drawn:
Normal-roughness texture
~~~~~~~~~~~~~~~~~~~~~~~~
.. note::
Normal-roughness texture is only supported in the Forward+ rendering method,
not Mobile or Compatibility.
Similarly, the normal-roughness texture can be used to read the normals and
roughness of objects rendered in the depth prepass. The normal is stored in the
``.xyz`` channels (mapped to the 0-1 range) while the roughness is stored in the

10
tutorials/shaders/shader_reference/shading_language.rst
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@@ -797,7 +797,7 @@ Full list of hints below:
+----------------------+--------------------------------------------------+-----------------------------------------------------------------------------+
| **sampler2D** | hint_depth_texture | Texture is the depth texture. |
+----------------------+--------------------------------------------------+-----------------------------------------------------------------------------+
| **sampler2D** | hint_normal_roughness_texture | Texture is the normal roughness texture. |
| **sampler2D** | hint_normal_roughness_texture | Texture is the normal roughness texture (only supported in Forward+). |
+----------------------+--------------------------------------------------+-----------------------------------------------------------------------------+
GDScript uses different variable types than GLSL does, so when passing variables
@@ -1285,8 +1285,8 @@ is used, it can be scalar or vector.
| gvec4_type **textureLod** (gsampler2D s, vec2 p, float lod) | Perform a texture read at custom mipmap. |
| | |
| gvec4_type **textureLod** (gsampler2DArray s, vec3 p, float lod) | The LOD defines which mipmap level is used. An LOD value of ``0.0`` |
| | will use the full resolution texture. |
| gvec4_type **textureLod** (gsampler3D s, vec3 p, float lod) | |
| | will use the full resolution texture. If the texture lacks mipmaps, |
| gvec4_type **textureLod** (gsampler3D s, vec3 p, float lod) | all LOD values will act like ``0.0``. |
| | |
| vec4 **textureLod** (samplerCube s, vec3 p, float lod) | |
| | |
@@ -1295,8 +1295,8 @@ is used, it can be scalar or vector.
| gvec4_type **textureProjLod** (gsampler2D s, vec3 p, float lod) | Performs a texture read with projection/LOD. |
| | |
| gvec4_type **textureProjLod** (gsampler2D s, vec4 p, float lod) | The LOD defines which mipmap level is used. An LOD value of ``0.0`` |
| | will use the full resolution texture. |
| gvec4_type **textureProjLod** (gsampler3D s, vec4 p, float lod) | |
| | will use the full resolution texture. If the texture lacks mipmaps, |
| gvec4_type **textureProjLod** (gsampler3D s, vec4 p, float lod) | all LOD values will act like ``0.0``. |
+-----------------------------------------------------------------------------+---------------------------------------------------------------------+
| gvec4_type **textureGrad** (gsampler2D s, vec2 p, vec2 dPdx, | Performs a texture read with explicit gradients. |
| vec2 dPdy) | |

5
tutorials/shaders/shaders_style_guide.rst
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@@ -30,14 +30,13 @@ Here is a complete shader example based on these guidelines:
shader_type canvas_item;
// Screen-space shader to adjust a 2D scene's brightness, contrast
// and saturation. Taken from
// https://github.com/godotengine/godot-demo-projects/blob/master/2d/screen_space_shaders/shaders/BCS.shader
// https://github.com/godotengine/godot-demo-projects/blob/master/2d/screen_space_shaders/shaders/BCS.gdshader
uniform sampler2D screen_texture : hint_screen_texture, filter_linear_mipmap;
uniform float brightness = 0.8;
uniform float contrast = 1.5;
uniform float saturation = 1.8;
uniform sampler2D screen_texture : hint_screen_texture, repeat_disable, filter_nearest;
void fragment() {
vec3 c = textureLod(screen_texture, SCREEN_UV, 0.0).rgb;