viewport drawing with gpu module #81334

New Issue

Jakub Uhlik · 2020-09-30T20:35:02+02:00

Jakub Uhlik commented

2020-09-30 20:35:02 +02:00

System Information
Operating system: Darwin-17.7.0-x86_64-i386-64bit 64 Bits

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-29 22:41, hash: e5aa9decb2
Worked: 2.90.1, 2.83.6
Started with 216d78687d

Short description of error
viewport drawing with gpu module, when scene is changed (something is deleted), object matrix is not correct until scene update, see video

Exact steps for others to reproduce the error
add an mesh (important, on empty it does not happen) object, run code, add another object, delete it, now matrix sent to shader is not correct (looks inverted?) until you for example select first object, if matrix is printed it is still the same, so i suspect something is happening on gpu
demo.mov

import bpy
import gpu
import bgl
from gpu_extras.batch import batch_for_shader
from mathutils import Matrix

vertex_shader = '''
in vec3 position;
in vec4 color;

uniform mat4 perspective_matrix;
uniform mat4 object_matrix;
uniform float point_size;
uniform float alpha_radius;
uniform float global_alpha;

out vec4 f_color;
out float f_alpha_radius;

void main()
{
    gl_Position = perspective_matrix * object_matrix * vec4(position, 1.0f);
    gl_PointSize = point_size;
    f_color = vec4(color[0], color[1], color[2], global_alpha);
    f_alpha_radius = alpha_radius;
}
'''

fragment_shader = '''
in vec4 f_color;
in float f_alpha_radius;

out vec4 fragColor;

void main()
{
    float r = 0.0f;
    float a = 1.0f;
    vec2 cxy = 2.0f * gl_PointCoord - 1.0f;
    r = dot(cxy, cxy);
    if(r > f_alpha_radius){
        discard;
    }
    fragColor = blender_srgb_to_framebuffer_space(f_color * a);
}
'''

coords = [(1, 1, 1), (2, 0, 0), (-2, -1, 3)]
colors = [(1, 0, 0, 1), (0, 1, 0, 1), (0, 0, 1, 1)]
shader = gpu.types.GPUShader(vertex_shader, fragment_shader)
batch = batch_for_shader(shader, 'POINTS', {"position": coords, "color": colors, })
o = bpy.context.active_object


def draw():
    bgl.glEnable(bgl.GL_PROGRAM_POINT_SIZE)
    bgl.glEnable(bgl.GL_DEPTH_TEST)
    bgl.glEnable(bgl.GL_BLEND)
    shader.bind()
    shader.uniform_float("perspective_matrix", bpy.context.region_data.perspective_matrix)
    shader.uniform_float("object_matrix", o.matrix_world)
    shader.uniform_float("point_size", 10)
    shader.uniform_float("alpha_radius", 1)
    shader.uniform_float("global_alpha", 1)
    batch.draw(shader)
    bgl.glDisable(bgl.GL_PROGRAM_POINT_SIZE)
    bgl.glDisable(bgl.GL_DEPTH_TEST)
    bgl.glDisable(bgl.GL_BLEND)


bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_VIEW')

for window in bpy.context.window_manager.windows:
    for area in window.screen.areas:
        if(area.type == 'VIEW_3D'):
            area.tag_redraw()

**System Information** Operating system: Darwin-17.7.0-x86_64-i386-64bit 64 Bits **Blender Version** Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-29 22:41, hash: `e5aa9decb2` Worked: 2.90.1, 2.83.6 Started with 216d78687d **Short description of error** viewport drawing with gpu module, when scene is changed (something is deleted), object matrix is not correct until scene update, see video **Exact steps for others to reproduce the error** add an mesh (important, on empty it does not happen) object, run code, add another object, delete it, now matrix sent to shader is not correct (looks inverted?) until you for example select first object, if matrix is printed it is still the same, so i suspect something is happening on gpu [demo.mov](https://archive.blender.org/developer/F8941209/demo.mov) ``` import bpy import gpu import bgl from gpu_extras.batch import batch_for_shader from mathutils import Matrix vertex_shader = ''' in vec3 position; in vec4 color; uniform mat4 perspective_matrix; uniform mat4 object_matrix; uniform float point_size; uniform float alpha_radius; uniform float global_alpha; out vec4 f_color; out float f_alpha_radius; void main() { gl_Position = perspective_matrix * object_matrix * vec4(position, 1.0f); gl_PointSize = point_size; f_color = vec4(color[0], color[1], color[2], global_alpha); f_alpha_radius = alpha_radius; } ''' fragment_shader = ''' in vec4 f_color; in float f_alpha_radius; out vec4 fragColor; void main() { float r = 0.0f; float a = 1.0f; vec2 cxy = 2.0f * gl_PointCoord - 1.0f; r = dot(cxy, cxy); if(r > f_alpha_radius){ discard; } fragColor = blender_srgb_to_framebuffer_space(f_color * a); } ''' coords = [(1, 1, 1), (2, 0, 0), (-2, -1, 3)] colors = [(1, 0, 0, 1), (0, 1, 0, 1), (0, 0, 1, 1)] shader = gpu.types.GPUShader(vertex_shader, fragment_shader) batch = batch_for_shader(shader, 'POINTS', {"position": coords, "color": colors, }) o = bpy.context.active_object def draw(): bgl.glEnable(bgl.GL_PROGRAM_POINT_SIZE) bgl.glEnable(bgl.GL_DEPTH_TEST) bgl.glEnable(bgl.GL_BLEND) shader.bind() shader.uniform_float("perspective_matrix", bpy.context.region_data.perspective_matrix) shader.uniform_float("object_matrix", o.matrix_world) shader.uniform_float("point_size", 10) shader.uniform_float("alpha_radius", 1) shader.uniform_float("global_alpha", 1) batch.draw(shader) bgl.glDisable(bgl.GL_PROGRAM_POINT_SIZE) bgl.glDisable(bgl.GL_DEPTH_TEST) bgl.glDisable(bgl.GL_BLEND) bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_VIEW') for window in bpy.context.window_manager.windows: for area in window.screen.areas: if(area.type == 'VIEW_3D'): area.tag_redraw() ```

Jakub Uhlik commented

2020-09-30 20:35:02 +02:00

Added subscriber: @JakubUhlik

blender-admin commented

2020-09-30 20:35:02 +02:00

#82843 was marked as duplicate of this issue

Dalai Felinto commented

2020-10-01 17:52:53 +02:00

Added subscribers: @Jeroen-Bakker, @dfelinto

Dalai Felinto commented

2020-10-01 17:52:53 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Dalai Felinto commented

2020-10-01 17:52:53 +02:00

@Jeroen-Bakker did anything change in 2.91 viewport that could have introduced that?

Philipp Oeser commented

2020-10-01 18:54:39 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-10-01 18:54:39 +02:00

I'll bet on 536c2e0ec9, will bisect.

I'll bet on 536c2e0ec9, will bisect.

Philipp Oeser commented

2020-10-01 19:26:52 +02:00

Well, it started with 216d78687d, then crashed for a couple of days, then no crash anymore somewhere around e4932d1167 (but bad as reported here)

Well, it started with 216d78687d, then crashed for a couple of days, then no crash anymore somewhere around e4932d1167 (but bad as reported here)

Philipp Oeser commented

2020-10-01 19:30:22 +02:00

Probably related: blender/blender-addons#80730 (BGL deprecation)

Philipp Oeser commented

2020-10-01 19:32:04 +02:00

Added subscriber: @fclem

Philipp Oeser commented

2020-10-01 19:32:04 +02:00

CC @fclem

Clément Foucault commented

2020-10-08 15:57:47 +02:00

I can't reproduce. Does that needs release builds? I don't understand how that would come from the refactor. Does that happens if you also deselect all object (alt+A)?

Philipp Oeser commented

2020-10-08 16:42:21 +02:00

In #81334#1030594, @fclem wrote:
I can't reproduce. Does that needs release builds? I don't understand how that would come from the refactor. Does that happens if you also deselect all object (alt+A)?

Happens in Debug builds as well. It also happens on deselection.

Now that I actually read the provided code, I am not sure if this is a bug anymore.
Upon deletion, there is no active object anymore, so accessing its matrix will fail

the object is defined outside the draw_handler function though, maybe thats why drawing also sticks to the object that was active at the time of script execution (and changing the active object does not change shader uniform?)
prior to 216d78687d it looks like the uniform doesnt change at all when active object changes
after 216d78687d I am actually getting an error (havent noticed before) : "StructRNA of type Object has been removed" [which seems correct]

@JakubUhlik : is the intention to stick this on the active object [and also change when active object changes]?
Then this line should move into the draw_handler function (with some fallback if no active object exists)?

o = bpy.context.active_object

If should just stick to the object that was active at the time of script execution (no change on change of active object), I guess you should get the matrix (or a copy) outside the draw handler function?

> In #81334#1030594, @fclem wrote: > I can't reproduce. Does that needs release builds? I don't understand how that would come from the refactor. Does that happens if you also deselect all object (alt+A)? Happens in Debug builds as well. It also happens on deselection. Now that I actually read the provided code, I am not sure if this is a bug anymore. Upon deletion, there is no active object anymore, so accessing its matrix will fail - the object is defined outside the draw_handler function though, maybe thats why drawing also sticks to the object that was active at the time of script execution (and changing the active object does not change shader uniform?) - prior to 216d78687d it looks like the uniform doesnt change at all when active object changes - after 216d78687d I am actually getting an error (havent noticed before) : "StructRNA of type Object has been removed" [which seems correct] @JakubUhlik : is the intention to stick this on the active object [and also change when active object changes]? Then this line should move into the draw_handler function (with some fallback if no active object exists)? ``` o = bpy.context.active_object ``` If should just stick to the object that was active at the time of script execution (no change on change of active object), I guess you should get the matrix (or a copy) outside the draw handler function?

Philipp Oeser commented

2020-10-08 16:44:53 +02:00

Changed status from 'Confirmed' to: 'Needs Developer To Reproduce'

Philipp Oeser commented

2020-10-08 16:44:53 +02:00

So might not be a bug here in the end, there has been a change in behavior in 216d78687d, but @fclem would have to comment again.

So might not be a bug here in the end, there has been a change in behavior in 216d78687d, but @fclem would have to comment again.

Jakub Uhlik commented

2020-10-08 17:29:23 +02:00

In #81334#1030629, @lichtwerk wrote:

In #81334#1030594, @fclem wrote:
I can't reproduce. Does that needs release builds? I don't understand how that would come from the refactor. Does that happens if you also deselect all object (alt+A)?

Happens in Debug builds as well. It also happens on deselection.

Now that I actually read the provided code, I am not sure if this is a bug anymore.
Upon deletion, there is no active object anymore, so accessing its matrix will fail

the object is defined outside the draw_handler function though, maybe thats why drawing also sticks to the object that was active at the time of script execution (and changing the active object does not change shader uniform?)

prior to 216d78687d it looks like the uniform doesnt change at all when active object changes

after 216d78687d I am actually getting an error (havent noticed before) : "StructRNA of type Object has been removed" [which seems correct]

@JakubUhlik : is the intention to stick this on the active object [and also change when active object changes]?
Then this line should move into the draw_handler function (with some fallback if no active object exists)?
o = bpy.context.active_object
If should just stick to the object that was active at the time of script execution (no change on change of active object), I guess you should get the matrix (or a copy) outside the draw handler function?

intention is, to draw something like it is part of an object, that is why i need its matrix for every draw i need to reflect its changes. if you swap active_object to something more defined, like o = bpy.data.objects['Plane'] problem is still there

> In #81334#1030629, @lichtwerk wrote: >> In #81334#1030594, @fclem wrote: >> I can't reproduce. Does that needs release builds? I don't understand how that would come from the refactor. Does that happens if you also deselect all object (alt+A)? > > Happens in Debug builds as well. It also happens on deselection. > > Now that I actually read the provided code, I am not sure if this is a bug anymore. > Upon deletion, there is no active object anymore, so accessing its matrix will fail > - the object is defined outside the draw_handler function though, maybe thats why drawing also sticks to the object that was active at the time of script execution (and changing the active object does not change shader uniform?) > - prior to 216d78687d it looks like the uniform doesnt change at all when active object changes > - after 216d78687d I am actually getting an error (havent noticed before) : "StructRNA of type Object has been removed" [which seems correct] > > @JakubUhlik : is the intention to stick this on the active object [and also change when active object changes]? > Then this line should move into the draw_handler function (with some fallback if no active object exists)? > ``` > o = bpy.context.active_object > ``` > If should just stick to the object that was active at the time of script execution (no change on change of active object), I guess you should get the matrix (or a copy) outside the draw handler function? intention is, to draw something like it is part of an object, that is why i need its matrix for every draw i need to reflect its changes. if you swap `active_object` to something more defined, like `o = bpy.data.objects['Plane']` problem is still there

Jakub Uhlik commented

2020-10-08 17:46:23 +02:00

for a side note, sorry if the example is a bit crude, but this worked for me from 2.80 until now, i wanted to isolate problem with least code amount possible while it being portable enough
https://github.com/uhlik/bpy#point-cloud-visualizer-for-blender-280
https://www.blendermarket.com/products/pcv

for a side note, sorry if the example is a bit crude, but this worked for me from 2.80 until now, i wanted to isolate problem with least code amount possible while it being portable enough https://github.com/uhlik/bpy#point-cloud-visualizer-for-blender-280 https://www.blendermarket.com/products/pcv

Jakub Uhlik commented

2020-10-09 12:29:22 +02:00

i played with it a bit more, there is no need to delete object (that is only i discovered there is something wrong)
selecting none, i.e. selecting background is all it needs.
also if code is run and no object is selected, i draw ok until view is moved, then it is wrong until any (!) object is selected
also checked win10, behaves the same
also prints from draw function are as they should, in this case

<bpy_struct, Object("Plane") at 0x7fe6fac41608>
<Matrix 4x4 (1.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 1.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 1.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 1.0000)>

b.mov

import bpy
import gpu
import bgl
from gpu_extras.batch import batch_for_shader
from mathutils import Matrix

vertex_shader = '''
in vec3 position;
in vec4 color;

uniform mat4 perspective_matrix;
uniform mat4 object_matrix;
uniform float point_size;
uniform float alpha_radius;
uniform float global_alpha;

out vec4 f_color;
out float f_alpha_radius;

void main()
{
    gl_Position = perspective_matrix * object_matrix * vec4(position, 1.0f);
    gl_PointSize = point_size;
    f_color = vec4(color[0], color[1], color[2], global_alpha);
    f_alpha_radius = alpha_radius;
}
'''

fragment_shader = '''
in vec4 f_color;
in float f_alpha_radius;

out vec4 fragColor;

void main()
{
    float r = 0.0f;
    float a = 1.0f;
    vec2 cxy = 2.0f * gl_PointCoord - 1.0f;
    r = dot(cxy, cxy);
    if(r > f_alpha_radius){
        discard;
    }
    fragColor = blender_srgb_to_framebuffer_space(f_color * a);
}
'''

coords = [(1, 1, 1), (2, 0, 0), (-2, -1, 3)]
colors = [(1, 0, 0, 1), (0, 1, 0, 1), (0, 0, 1, 1)]
shader = gpu.types.GPUShader(vertex_shader, fragment_shader)
batch = batch_for_shader(shader, 'POINTS', {"position": coords, "color": colors, })
# o = bpy.context.active_object
o = bpy.data.objects['Plane']


def draw():
    bgl.glEnable(bgl.GL_PROGRAM_POINT_SIZE)
    bgl.glEnable(bgl.GL_DEPTH_TEST)
    bgl.glEnable(bgl.GL_BLEND)
    shader.bind()
    shader.uniform_float("perspective_matrix", bpy.context.region_data.perspective_matrix)
    print(o)
    print(o.matrix_world)
    shader.uniform_float("object_matrix", o.matrix_world)
    shader.uniform_float("point_size", 10)
    shader.uniform_float("alpha_radius", 1)
    shader.uniform_float("global_alpha", 1)
    batch.draw(shader)
    bgl.glDisable(bgl.GL_PROGRAM_POINT_SIZE)
    bgl.glDisable(bgl.GL_DEPTH_TEST)
    bgl.glDisable(bgl.GL_BLEND)


bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_VIEW')

for window in bpy.context.window_manager.windows:
    for area in window.screen.areas:
        if(area.type == 'VIEW_3D'):
            area.tag_redraw()

i played with it a bit more, there is no need to delete object (that is only i discovered there is something wrong) selecting none, i.e. selecting background is all it needs. also if code is run and no object is selected, i draw ok until view is moved, then it is wrong until any (!) object is selected also checked win10, behaves the same also prints from draw function are as they should, in this case ``` <bpy_struct, Object("Plane") at 0x7fe6fac41608> <Matrix 4x4 (1.0000, 0.0000, 0.0000, 0.0000) (0.0000, 1.0000, 0.0000, 0.0000) (0.0000, 0.0000, 1.0000, 0.0000) (0.0000, 0.0000, 0.0000, 1.0000)> ``` [b.mov](https://archive.blender.org/developer/F8970882/b.mov) ``` import bpy import gpu import bgl from gpu_extras.batch import batch_for_shader from mathutils import Matrix vertex_shader = ''' in vec3 position; in vec4 color; uniform mat4 perspective_matrix; uniform mat4 object_matrix; uniform float point_size; uniform float alpha_radius; uniform float global_alpha; out vec4 f_color; out float f_alpha_radius; void main() { gl_Position = perspective_matrix * object_matrix * vec4(position, 1.0f); gl_PointSize = point_size; f_color = vec4(color[0], color[1], color[2], global_alpha); f_alpha_radius = alpha_radius; } ''' fragment_shader = ''' in vec4 f_color; in float f_alpha_radius; out vec4 fragColor; void main() { float r = 0.0f; float a = 1.0f; vec2 cxy = 2.0f * gl_PointCoord - 1.0f; r = dot(cxy, cxy); if(r > f_alpha_radius){ discard; } fragColor = blender_srgb_to_framebuffer_space(f_color * a); } ''' coords = [(1, 1, 1), (2, 0, 0), (-2, -1, 3)] colors = [(1, 0, 0, 1), (0, 1, 0, 1), (0, 0, 1, 1)] shader = gpu.types.GPUShader(vertex_shader, fragment_shader) batch = batch_for_shader(shader, 'POINTS', {"position": coords, "color": colors, }) # o = bpy.context.active_object o = bpy.data.objects['Plane'] def draw(): bgl.glEnable(bgl.GL_PROGRAM_POINT_SIZE) bgl.glEnable(bgl.GL_DEPTH_TEST) bgl.glEnable(bgl.GL_BLEND) shader.bind() shader.uniform_float("perspective_matrix", bpy.context.region_data.perspective_matrix) print(o) print(o.matrix_world) shader.uniform_float("object_matrix", o.matrix_world) shader.uniform_float("point_size", 10) shader.uniform_float("alpha_radius", 1) shader.uniform_float("global_alpha", 1) batch.draw(shader) bgl.glDisable(bgl.GL_PROGRAM_POINT_SIZE) bgl.glDisable(bgl.GL_DEPTH_TEST) bgl.glDisable(bgl.GL_BLEND) bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_VIEW') for window in bpy.context.window_manager.windows: for area in window.screen.areas: if(area.type == 'VIEW_3D'): area.tag_redraw() ```

Campbell Barton commented

2021-01-28 05:18:03 +01:00

Added subscriber: @ideasman42

Campbell Barton commented

2021-01-28 05:18:03 +01:00

@JakubUhlik I was looking into another bug caused by 216d78687d and thought it might be related.

Could you check if this bug is still happening?

I can't redo the error with e5aa9decb23f or latest master (862aa2a66bba922fbc4a24cc8a43a16e290e64cf)

Could you list exact steps to redo the error? (while it may seem obvious, since I can't redo it - there may be some step I'm missing).

@JakubUhlik I was looking into another bug caused by 216d78687d and thought it might be related. Could you check if this bug is still happening? I can't redo the error with `e5aa9decb23f` or latest master (`862aa2a66bba922fbc4a24cc8a43a16e290e64cf`) Could you list exact steps to redo the error? (while it may seem obvious, since I can't redo it - there may be some step I'm missing).

Campbell Barton commented

2021-01-28 05:18:54 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Needs User Info'

Jakub Uhlik commented

2021-01-28 08:12:37 +01:00

@ideasman42 yes, it is still happening in
version: 2.92.0 Beta, branch: master, commit date: 2021-01-18 17:08, hash: b5c3f26cba, type: Release
version: 2.93.0 Alpha, branch: master, commit date: 2021-01-19 22:43, hash: 6290091bac, type: Release

and bgl.glDepthFunc(bgl.GL_LEQUAL) fixes that behavior

@ideasman42 yes, it is still happening in version: 2.92.0 Beta, branch: master, commit date: 2021-01-18 17:08, hash: b5c3f26cba81, type: Release version: 2.93.0 Alpha, branch: master, commit date: 2021-01-19 22:43, hash: 6290091bace2, type: Release and `bgl.glDepthFunc(bgl.GL_LEQUAL)` fixes that behavior

Jakub Uhlik commented

2021-01-28 08:16:34 +01:00

ah, steps, add a Plane, run script, click outside to deselect Plane, drawn dots will be flipped

Jakub Uhlik commented

2021-01-28 08:18:21 +01:00

version: 2.93.0 Alpha, branch: master, commit date: 2021-01-27 22:47, hash: df135b74fc, type: Release - broken as well

version: 2.93.0 Alpha, branch: master, commit date: 2021-01-27 22:47, hash: df135b74fc93, type: Release - broken as well

Jakub Uhlik commented

2021-01-28 08:22:34 +01:00

one more thing, if there is an empty in scene, it works as it should, if there is only mesh objects it flips on deselect

Campbell Barton commented

2021-01-28 10:10:10 +01:00

Still cant redo:

OS: Linux 5.10.10-arch1-1
REV: 39cfc95c2cc3829d6dbc5e1f6fdda3a0e053ed4d
GPU: [AMD/ATI] Navi 10 [Radeon RX 5600 OEM/5600 XT / 5700/5700 XT]

Still cant redo: * OS: Linux 5.10.10-arch1-1 * REV: `39cfc95c2cc3829d6dbc5e1f6fdda3a0e053ed4d` * GPU: `[AMD/ATI] Navi 10 [Radeon RX 5600 OEM/5600 XT / 5700/5700 XT]`

Jakub Uhlik commented

2021-01-28 10:20:41 +01:00

you have to have with empty scene, no camera, no anything drawn with lines, like this
a.mp4

you have to have with empty scene, no camera, no anything drawn with lines, like this [a.mp4](https://archive.blender.org/developer/F9602302/a.mp4)

Jakub Uhlik commented

2021-01-28 10:23:49 +01:00

this is related i think https://developer.blender.org/T82843