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OpenGL question about deferred rendering

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Hi,

I'm trying to implement deferred rendering in a modern way using OGL 4.x core. For this goal I've read several articles pdfs, tutorials etc. about this topic, however I still have some questions.
First of all, when I create a G-buffer what do I really do?
I mean I surely want to create a FBO and an RBO and attach the RBO to the FBO so that I can render to a texture which I attach to the FBO.
But then how do I attach other stuff to the FBO?
As I've read I definitely will need at least an albedo a depth and a normal buffer. I suppose these will all be textures. However there are many formats to choose from, and it depends on the article (or rather game engine) which is used.
Which are the most common, or rather the most efficient, and nicest ones?
(to add I definitely want to go with the full HDR pipeline)
Another question is: how do I fill these buffers?
Especially when there are object in my scene which doesn't have textures or normals. And there is the cube mapping which should be completely untouched, since I only need the colors of it.
Finally, I ran into an article from Intel in which the whole shading part was solved within a compute shader. So how can I connect OpenCL and OpenGL so that I can get the same results with open source APIs?

Best regards,
Yours3!f

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Hi,

I'm trying to implement deferred rendering in a modern way using OGL 4.x core. For this goal I've read several articles pdfs, tutorials etc. about this topic, however I still have some questions.
First of all, when I create a G-buffer what do I really do?
I mean I surely want to create a FBO and an RBO and attach the RBO to the FBO so that I can render to a texture which I attach to the FBO.
But then how do I attach other stuff to the FBO?
As I've read I definitely will need at least an albedo a depth and a normal buffer. I suppose these will all be textures. However there are many formats to choose from, and it depends on the article (or rather game engine) which is used.
Which are the most common, or rather the most efficient, and nicest ones?
(to add I definitely want to go with the full HDR pipeline)
Another question is: how do I fill these buffers?
Especially when there are object in my scene which doesn't have textures or normals. And there is the cube mapping which should be completely untouched, since I only need the colors of it.
Finally, I ran into an article from Intel in which the whole shading part was solved within a compute shader. So how can I connect OpenCL and OpenGL so that I can get the same results with open source APIs?

Best regards,
Yours3!f


Well I am trying to work on the same thing and I can only attempt to try and answer one of your questions, "How do I fill these buffers?". And I believe to fill them you bind them before drawing and then your shader should output its final data to your buffer. I am not 100% sure if that is right, but I think it is.

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something like this?


glActiveTexture(GL_TEXTURE0);
texture0.bind();
glActiveTexture(GL_TEXTURE0 + 1);
albedo_texture.bind();
glActiveTexture(GL_TEXTURE0 + 2);
normal_texture.bind();
glActiveTexture(GL_TEXTURE0 + 3);
depth_texture.bind();
glUniform1i(texture0_location, GL_TEXTURE0);
glUniform1i(albedo_location, GL_TEXTURE0 + 1);
glUniform1i(normal_location, GL_TEXTURE0 + 2);
glUniform1i(depth_location, GL_TEXTURE0 + 3);
//render stuff...

(pixel shader)
#version 410
uniform sampler2D texture0;
uniform sampler2D albedo;
uniform sampler2D normal;
uniform sampler2D depth;

in vec3 normals;
in vec4 position;
smooth in vec2 texture_coordinates;

out vec4 fragment_color;

void main()
{
depth = position.z;
normal = vec4(normals, 1.0);
fragment_color = albedo = texture(texture0, texture_coordinates);
}

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About the texture formats:

I've looked at the possible formats found here:
http://www.opengl.or...ki/Image_Format
and I've read about them a lot.

I've found an nvidia HDR sample that has an FPS and a timer as well with it, which features some of these formats:

From best performance to worst:

HDR format RT format FPS time (ms)
RGB9_E5 R11F_G11F_B10F 750 1.31
R11F_G11F_B10F R11F_G11F_B10F 740 1.32
RGBA16F R11F_G11F_B10F 725 1.40
RGBA32F R11F_G11F_B10F 610 1.63
RGB9_E5 RGBA16F 523 1.91
R11F_G11F_B10F RGBA16F 523 1.91
RGBA16F RGBA16F 512 1.95
RGBA32F RGBA16F 470 2.12
RGB9_E5 RGBA32F 292 3.43
R11F_G11F_B10F RGBA32F 291 3.43
RGBA16F RGBA32F 288 3.46
RGBA32F RGBA32F 277 3.6

These were achieved with a Core i3 540, a HD 5770 with 1GB GDDR5, and on 1440x900.

I didn't notice any visual difference only when using a RGBA32F HDR format. However this might be because of some bug.
To add when using high performance formats like RGB9_E5 some visual glitches might appear if we combine this with other effects.
Another thing to notice is that if we want to make the game go with 30 FPS then in the worst case HDR rendering took 10% of the rendering time, in the best it only took 4.36%. Using an easily implementable format like the RGBA16F + RGBA16F would be the best way in my opinion because it takes 6.5% of the rendering time which is nice, and we still have enough precision.

On the other hand I've read the deferred rendering tutorial on Catalina's XNA blog, in which several combinations are mentioned for the G-buffer, from which the best seemed to be using a RGBA16F for albedo, R16G16F (I don't know if there's such format in OGL) for normal data (or maybe RGB10_A2), and R32F for position data. This would use about 33 MB of memory and would leave 1 channel of 16 bit data free to use for other purposes such as storing material ID. I think there would be need for another G-buffer component for other stuff like specular intensity and exponent material ID etc. For this a RGBA, or RGB format could be used.

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Did you already understand how it works? Add multiple out variables to the shader, and use glBindFragDataLocation before linking shader. And when rendering, call glDrawBuffers to tell what buffers you are using.


out vec4 depthFrag;
out vec4 normalFrag;
// ... whatever you want

void main() {
depthFrag = vec4(...);
normalFrag = vec4(...);
}



// Create shader program and attach shaders here

// Bind frag data locations
glBindFragDataLocation(shaderProgram, 0, "depthFrag");
glBindFragDataLocation(shaderProgram, 1, "normalFrag");

glLinkShader(shaderProgram);

// And when rendering, tell what buffers we will be using

GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1};
glDrawBuffers(2, buffers);


Hope this helps.

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No actually I didn't understand it until this point :) I just thought about it on a theoretical basis, but yeah that's what I was looking for, thank you.

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Ok, I tried to implement it, but in the final lighting stage I seem to be getting no normals or depth, and I also think that depth isn't calculated properly. I do get the albedo, which is great, but due to the lack of the other two components I can't do lighting.

So here's my initialization:

void deferred::init()
{
//load the lighting shader
objs::get()->shader_loader.load_shader_control_file ( "../shaders/deferred/fs_quad.sc", &fs_quad );

//load the full-screen quad
objs::get()->obj.load_obj_file ( "../resources/fs_quad.obj", &quad, &fs_quad );

//set texture parameters

float w = objs::get()->conf.SCREEN_WIDTH;
float h = objs::get()->conf.SCREEN_HEIGHT;

fbo.create(); //generate a fbo
fbo.bind(); //bind it

GLenum modes[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2 };
//set which draw buffers will it use
glDrawBuffers ( 3, modes );

//create render buffers
rb_albedo.create();
rb_normal.create();
rb_position.create();
rb_depth.create(); //this is not a g-buffer component it is just a depth attachment

//bind render buffers, set the storage format, and attach them to the fbo
rb_albedo.bind();
rb_albedo.set_storage_format ( GL_RGBA16F, w, h );
rb_albedo.attach_to_frame_buffer ( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, &fbo );
rb_normal.bind();
rb_normal.set_storage_format ( GL_RG16F, w, h );
rb_normal.attach_to_frame_buffer ( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, &fbo );
rb_position.bind();
rb_position.set_storage_format ( GL_R32F, w, h );
rb_position.attach_to_frame_buffer ( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, &fbo );
rb_depth.bind();
rb_depth.set_storage_format ( GL_DEPTH_COMPONENT32, w, h );
rb_depth.attach_to_frame_buffer ( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, &fbo );

//create textures
albedo.create();
normals.create();
position.create();

//set the albedo as the 5th (4) texture
glActiveTexture ( GL_TEXTURE4 );
albedo.bind(); //bind it
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
//use rgba16f format
glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGBA16F, w, h, 0, GL_RGBA, GL_FLOAT, 0 );
albedo.set_dimensions ( w, h ); //store the size of the texture for future use

glActiveTexture ( GL_TEXTURE5 );
normals.bind();
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexImage2D ( GL_TEXTURE_2D, 0, GL_RG16F, w, h, 0, GL_RGBA, GL_FLOAT, 0 );
normals.set_dimensions ( w, h );

glActiveTexture ( GL_TEXTURE6 );
position.bind();
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexImage2D ( GL_TEXTURE_2D, 0, GL_R32F, w, h, 0, GL_RGBA, GL_FLOAT, 0 );
position.set_dimensions ( w, h );

//reset the active texture
glActiveTexture ( GL_TEXTURE0 );

//attach textures to fbo
albedo.attach_to_frame_buffer ( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, &fbo );
normals.attach_to_frame_buffer ( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, &fbo );
position.attach_to_frame_buffer ( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, &fbo );

fbo.unbind();
}


here's the rendering code

void deferred::render()
{
//set orthographic view w, h, near, far
event::get()->get_resize()->set_orthographic ( 1.0f, 1.0f, -1.0f, 1.0f );
//disable depth testing
glDisable(GL_DEPTH_TEST);
//bind the lighting shader
fs_quad.bind();
//pass the matrices and scene information
fs_quad.pass_m4x4 ( objs::get()->ppl.get_projection_matrix(), "m4_p" );
fs_quad.pass_m4x4 ( objs::get()->ppl.get_model_view_matrix(), "m4_mv" );
//reset perspective mode
event::get()->get_resize()->set_perspective ();
//inverse projection matrix for depth to position reconstruction
fs_quad.pass_m4x4 ( objs::get()->ppl.get_projection_matrix().invert(), "inv_proj" );
//pass camera position
fs_quad.pass_vec4 ( mymath::vec4f ( objs::get()->cam.pos[0], objs::get()->cam.pos[1], objs::get()->cam.pos[2], 1.0f ), "cam_pos" );
//pass the textures
fs_quad.pass_int ( 4, "texture4" );
fs_quad.pass_int ( 5, "texture5" );
fs_quad.pass_int ( 6, "texture6" );
//draw full screen quad
quad.render();
//unbind the lighting shader
fs_quad.unbind();
//enable depth testing
glEnable(GL_DEPTH_TEST);
}


the shader that fills the G-buffer

//vertex shader
#version 410

//projection, modelview matrices
uniform mat4 m4_p, m4_mv;
uniform mat3 m3_n;

//the vertex position
in vec4 v4_vertex;
//the texture coordinates
in vec2 v2_texture;
in vec3 v3_normal;

smooth out vec2 v2_texture_coords;
out vec2 normal;
out float depth;

vec2 encode_normal_x_y_reconstruct_z(vec3 in_normal)
{
return vec2(in_normal.xy * 0.5 + 0.5);
}

void main()
{
normal = encode_normal_x_y_reconstruct_z(m3_n * v3_normal);
v2_texture_coords = v2_texture;

gl_Position = m4_p * m4_mv * v4_vertex;
depth = gl_Position.z / gl_Position.w;
}

//////////////////////////////////////////-------------------------------------------------------------

//pixel shader
#version 410

uniform sampler2D texture0;

smooth in vec2 v2_texture_coords;
in vec2 normal;
in float depth;

out vec4 v4_color; //color attachment0
out vec4 v4_normal; //c. a. 1
out vec4 v4_depth; //c. a. 2

void main()
{
v4_normal.xy = normal;
v4_depth.x = depth;
v4_color = texture(texture0, v2_texture_coords);
}


Using this shader the normals here seem to be good when I draw them: v4_color = vec4(v2_normal, 0.0, 1.0);
however when I draw the depth the mesh get all black, instead of that grayscale depth look. v4_color = vec4(vec3(depth), 1.0);
I also use the glBindFragDataLocation before linking as you suggested, although I don't know if it was bound

the lighting shader:


//vertex shader
#version 410

//projection, modelview matrices
uniform mat4 m4_p, m4_mv;

//the vertex position
in vec4 v4_vertex;
//the texture coordinates
in vec2 v2_texture;

smooth out vec2 v2_texture_coords;

void main()
{
v2_texture_coords = v2_texture;
gl_Position = m4_p * m4_mv * v4_vertex;
}


///////////////////////////////////---------------------------------------------------------------------------

//pixel shader
#version 410

uniform sampler2D texture4; //albedo RGBA16F
uniform sampler2D texture5; //normal RG16F
uniform sampler2D texture6; //depth R32F

smooth in vec2 v2_texture_coords; //texture coordinates for the G-buffer
uniform mat4 inv_proj; //inverse projection matrix
uniform vec4 cam_pos; //camera position

out vec4 v4_color; //the outgoing color

vec3 decode_normal_x_y_reconstruct_z(vec2 in_normal)
{
vec3 out_normal;
out_normal.xy = in_normal * 2 - 1; //convert from range [0.0, 1.0] to [-1.0, 1.0]
out_normal.z = sqrt(1 - dot(out_normal.xy, out_normal.xy)); //since it is perpendicular to x and y we can calculate it
return out_normal;
}

void main()
{
vec4 albedo = texture(texture4, v2_texture_coords);
vec3 normal = decode_normal_x_y_reconstruct_z(texture(texture5, v2_texture_coords).xy);
float depth = texture(texture6, v2_texture_coords).x;

//get texture coords from [0, 1] to [-1, 1], add them as x and y, add depth as z, and multiply by inverse projection matrix
vec4 position = vec4(v2_texture_coords.x * 2.0 - 1.0, -(v2_texture_coords.y * 2.0 - 1.0), depth, 1.0) * inv_proj;
position /= position.w;

//blinn lighting with a light placed at [0, 5, -2]
vec3 light = vec3( 0.0, 5.0, -2.0);
vec3 light_dir = normalize(light - position.xyz);
vec3 eye_dir = normalize(cam_pos.xyz - position.xyz);
vec3 half_vec = normalize(light_dir + eye_dir);
v4_color = max(dot(normal, light_dir), 0.0) * albedo + pow(max(dot(normal, half_vec), 0.0), 9.0) * 10.0;
}


When I try to draw the normals with v4_color = vec4(normal, 1.0); I get a black screen, this also happens with depth. Please help I'm struggling to get this working.

Best regards,
Yours3!f

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I think you have to call glDrawBuffers every time you want to render something on the buffers. It's probably using only the first buffer now (which is albedo), because you don't tell it what to use when rendering.

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I think you have to call glDrawBuffers every time you want to render something on the buffers. It's probably using only the first buffer now (which is albedo), because you don't tell it what to use when rendering.


Thanks, but you don't have to do this every frame. I know on Codinglabs in the tutorial it is done every frame, but you simply don't have to, because it only sets up the frame buffer object, so that it actually recieves the color input.

I updated the code (see the post above), and now I do get the color information, depth and normals as well.

Now I suppose the lighting equation or the decoding function is wrong, since I have all the data.

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ok so I tried to figure out why my ligthing doesn't work, so I tried some things.

first of all if in the lighting shader I gather the normal and depth and convert them the conversion works.

void main()
{
vec3 normal = decode_normal_x_y_reconstruct_z(texture(texture5, v2_texture_coords).xy);
float depth = texture(texture6, v2_texture_coords).x;

//get texture coords from [0, 1] to [-1, 1], add them as x and y, add depth as z, and multiply by inverse projection matrix
vec4 position = vec4(v2_texture_coords.x * 2.0 - 1.0, -(v2_texture_coords.y * 2.0 - 1.0), depth, 1.0) * inv_proj;
position /= position.w;

v4_color = vec4(normal, 1.0); //gives me a normal looking scene
//v4_color = vec4(vec3(depth), 1.0); //gives me a depth looking scene
//v4_color = position; //gives me a position scene (well it is red green and blue :) )
}


However when I do this I get a black screen:

void main()
{
v4_color = texture(texture4, v2_texture_coords);
vec3 normal = decode_normal_x_y_reconstruct_z(texture(texture5, v2_texture_coords).xy);

v4_color = vec4(normal, 1.0); //this should give me a normal looking scene
}


I have no idea why that happens, and I guess this is why my lighting doesn't work too...

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    • By norman784
      I'm having issues loading textures, as I'm clueless on how to handle / load images maybe I missing something, but the past few days I just google a lot to try to find a solution. Well theres two issues I think, one I'm using Kotlin Native (EAP) and OpenGL wrapper / STB image, so I'm not quite sure wheres the issue, if someone with more experience could give me some hints on how to solve this issue?
      The code is here, if I'm not mistaken the workflow is pretty straight forward, stbi_load returns the pixels of the image (as char array or byte array) and you need to pass those pixels directly to glTexImage2D, so a I'm missing something here it seems.
      Regards
    • By Hashbrown
      I've noticed in most post processing tutorials several shaders are used one after another: one for bloom, another for contrast, and so on. For example: 
      postprocessing.quad.bind() // Effect 1 effect1.shader.bind(); postprocessing.texture.bind(); postprocessing.quad.draw(); postprocessing.texture.unbind(); effect1.shader.unbind(); // Effect 2 effect2.shader.bind(); // ...and so on postprocessing.quad.unbind() Is this good practice, how many shaders can I bind and unbind before I hit performance issues? I'm afraid I don't know what the good practices are in open/webGL regarding binding and unbinding resources. 
      I'm guessing binding many shaders at post processing is okay since the scene has already been updated and I'm just working on a quad and texture at that moment. Or is it more optimal to put shader code in chunks and bind less frequently? I'd love to use several shaders at post though. 
      Another example of what I'm doing at the moment:
      1) Loop through GameObjects, bind its phong shader (send color, shadow, spec, normal samplers), unbind all.
      2) At post: bind post processor quad, and loop/bind through different shader effects, and so on ...
      Thanks all! 
    • By phil67rpg
      void collision(int v) { collision_bug_one(0.0f, 10.0f); glutPostRedisplay(); glutTimerFunc(1000, collision, 0); } void coll_sprite() { if (board[0][0] == 1) { collision(0); flag[0][0] = 1; } } void erase_sprite() { if (flag[0][0] == 1) { glColor3f(0.0f, 0.0f, 0.0f); glBegin(GL_POLYGON); glVertex3f(0.0f, 10.0f, 0.0f); glVertex3f(0.0f, 9.0f, 0.0f); glVertex3f(1.0f, 9.0f, 0.0f); glVertex3f(1.0f, 10.0f, 0.0f); glEnd(); } } I am using glutTimerFunc to wait a small amount of time to display a collision sprite before I black out the sprite. unfortunately my code only blacks out the said sprite without drawing the collision sprite, I have done a great deal of research on the glutTimerFunc and  animation.
    • By Lewa
      So, i stumbled upon the topic of gamma correction.
      https://learnopengl.com/Advanced-Lighting/Gamma-Correction
      So from what i've been able to gather: (Please correct me if i'm wrong)
      Old CRT monitors couldn't display color linearly, that's why gamma correction was nessecary. Modern LCD/LED monitors don't have this issue anymore but apply gamma correction anyway. (For compatibility reasons? Can this be disabled?) All games have to apply gamma correction? (unsure about that) All textures stored in file formats (.png for example) are essentially stored in SRGB color space (as what we see on the monitor is skewed due to gamma correction. So the pixel information is the same, the percieved colors are just wrong.) This makes textures loaded into the GL_RGB format non linear, thus all lighting calculations are wrong You have to always use the GL_SRGB format to gamma correct/linearise textures which are in SRGB format  
      Now, i'm kinda confused how to proceed with applying gamma correction in OpenGL.
      First of, how can i check if my Monitor is applying gamma correction? I noticed in my monitor settings that my color format is set to "RGB" (can't modify it though.) I'm connected to my PC via a HDMI cable. I'm also using the full RGB range (0-255, not the 16 to ~240 range)
       
      What i tried to do is to apply a gamma correction shader shown in the tutorial above which looks essentially like this: (it's a postprocess shader which is applied at the end of the renderpipeline)
      vec3 gammaCorrection(vec3 color){ // gamma correction color = pow(color, vec3(1.0/2.2)); return color; } void main() { vec3 color; vec3 tex = texture2D(texture_diffuse, vTexcoord).rgb; color = gammaCorrection(tex); outputF = vec4(color,1.0f); } The results look like this:
      No gamma correction:
      With gamma correction:
       
      The colors in the gamma corrected image look really wased out. (To the point that it's damn ugly. As if someone overlayed a white half transparent texture. I want the colors to pop.)
      Do i have to change the textures from GL_RGB to GL_SRGB in order to gamma correct them in addition to applying the post process gamma correction shader? Do i have to do the same thing with all FBOs? Or is this washed out look the intended behaviour?
    • By OneKaidou
      Hi
       
      I am trying to program shadow volumes and i stumbled upon an artifact which i can not find the cause for.
      I generate the shadow volumes using a geometry shader with reversed extrusion (projecting the lightfacing triangles to infinity) and write the stencil buffer according to z-fail. The base of my code is the "lighting" chapter from learnopengl.com, where i extended the shader class to include geometry shader. I also modified the "lightingshader" to draw the ambient pass when "pass" is set to true and the diffuse/ specular pass when set to false. For easier testing i added a view controls to switch on/off the shadow volumes' color rendering or to change the cubes' position, i made the lightnumber controllable and changed the diffuse pass to render green for easier visualization of my problem.
       
      The first picture shows the rendered scene for one point light, all cubes and the front cube's shadow volume is the only one created (intentional). Here, all is rendered as it should be with all lit areas green and all areas inside the shadow volume black (with the volume's sides blended over).

      If i now turn on the shadow volumes for all the other cubes, we get a bit of a mess, but its also obvious that some areas that were in shadow before are now erroneously lit (for example the first cube to the right from the originaly shadow volumed cube). From my testing the areas erroneously lit are the ones where more than one shadow volume marks the area as shadowed.

      To check if a wrong stencil buffer value caused this problem i decided to change the stencil function for the diffuse pass to only render if the stencil is equal to 2. As i repeated this approach with different values for the stencil function i found out that if i set the value equal to 1 or any other uneven value the lit and shadowed areas are inverted and if i set it to 0 or any other even value i get the results shown above.
      This lead me to believe that the value and thus the stencil buffer values may be clamped to [0,1] which would also explain the artifact, because twice in shadow would equal in no shadow at all, but from what i found on the internet and from what i tested with
      GLint stencilSize = 0; glGetFramebufferAttachmentParameteriv(GL_DRAW_FRAMEBUFFER, GL_STENCIL, GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE, &stencilSize); my stencilsize is 8 bit, which should be values within [0,255].
      Does anyone know what might be the cause for this artifact or the confusing results with other stencil functions?
       
      // [the following code includes all used gl* functions, other parts are due to readability partialy excluded] // glfw: initialize and configure // ------------------------------ glfwInit(); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 4); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // glfw window creation // -------------------- GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL); if (window == NULL) { cout << "Failed to create GLFW window" << endl; glfwTerminate(); return -1; } glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); glfwSetCursorPosCallback(window, mouse_callback); glfwSetScrollCallback(window, scroll_callback); // tell GLFW to capture our mouse glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED); // glad: load all OpenGL function pointers // --------------------------------------- if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { cout << "Failed to initialize GLAD" << endl; return -1; } // ==================================================================================================== // window and functions are set up // ==================================================================================================== // configure global opengl state // ----------------------------- glEnable(GL_DEPTH_TEST); glEnable(GL_CULL_FACE); // build and compile our shader program [...] // set up vertex data (and buffer(s)) and configure vertex attributes [...] // shader configuration [...] // render loop // =========== while (!glfwWindowShouldClose(window)) { // input processing and fps calculation[...] // render // ------ glClearColor(0.1f, 0.1f, 0.1f, 1.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glDepthMask(GL_TRUE); //enable depth writing glDepthFunc(GL_LEQUAL); //avoid z-fighting //draw ambient component into color and depth buffer view = camera.GetViewMatrix(); projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f); // setting up lighting shader for ambient pass [...] // render the cubes glBindVertexArray(cubeVAO); for (unsigned int i = 0; i < 10; i++) { //position cube [...] glDrawArrays(GL_TRIANGLES, 0, 36); } //------------------------------------------------------------------------------------------------------------------------ glDepthMask(GL_FALSE); //disable depth writing glEnable(GL_BLEND); glBlendFunc(GL_ONE, GL_ONE); //additive blending glEnable(GL_STENCIL_TEST); //setting up shadowShader and lightingShader [...] for (int light = 0; light < lightsused; light++) { glDepthFunc(GL_LESS); glClear(GL_STENCIL_BUFFER_BIT); //configure stencil ops for front- and backface to write according to z-fail glStencilOpSeparate(GL_FRONT, GL_KEEP, GL_DECR_WRAP, GL_KEEP); //-1 for front-facing glStencilOpSeparate(GL_BACK, GL_KEEP, GL_INCR_WRAP, GL_KEEP); //+1 for back-facing glStencilFunc(GL_ALWAYS, 0, GL_TRUE); //stencil test always passes if(hidevolumes) glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE); //disable writing to the color buffer glDisable(GL_CULL_FACE); glEnable(GL_DEPTH_CLAMP); //necessary to render SVs into infinity //draw SV------------------- shadowShader.use(); shadowShader.setInt("lightnr", light); int nr; if (onecaster) nr = 1; else nr = 10; for (int i = 0; i < nr; i++) { //position cube[...] glDrawArrays(GL_TRIANGLES, 0, 36); } //-------------------------- glDisable(GL_DEPTH_CLAMP); glEnable(GL_CULL_FACE); glStencilFunc(GL_EQUAL, 0, GL_TRUE); //stencil test passes for ==0 so only for non shadowed areas glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP); //keep stencil values for illumination glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE); //enable writing to the color buffer glDepthFunc(GL_LEQUAL); //avoid z-fighting //draw diffuse and specular pass lightingShader.use(); lightingShader.setInt("lightnr", light); // render the cubes for (unsigned int i = 0; i < 10; i++) { //position cube[...] glDrawArrays(GL_TRIANGLES, 0, 36); } } glDisable(GL_BLEND); glDepthMask(GL_TRUE); //enable depth writing glDisable(GL_STENCIL_TEST); //------------------------------------------------------------------------------------------------------------------------ // also draw the lamp object(s) [...] // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.) // ------------------------------------------------------------------------------- glfwSwapBuffers(window); glfwP } // optional: de-allocate all resources once they've outlived their purpose: // ------------------------------------------------------------------------ glDeleteVertexArrays(1, &cubeVAO); glDeleteVertexArrays(1, &lightVAO); glDeleteBuffers(1, &VBO); // glfw: terminate, clearing all previously allocated GLFW resources. // ------------------------------------------------------------------ glfwTerminate(); return 0;  
    • By Green_Baron
      Hi,
      i am self teaching me graphics and oo programming and came upon this:
      My Window class creates an input handler instance, the glfw user pointer is redirected to that object and methods there do the input handling for keyboard and mouse. That works. Now as part of the input handling i have an orbiting camera that is controlled by mouse movement. GLFW_CURSOR_DISABLED is set as proposed in the glfw manual. The manual says that in this case the cursor is automagically reset to the window's center. But if i don't reset it manually with glfwSetCursorPos( center ) mouse values seem to add up until the scene is locked up.
      Here are some code snippets, mostly standard from tutorials:
      // EventHandler m_eventHandler = new EventHandler( this, glm::vec3( 0.0f, 5.0f, 0.0f ), glm::vec3( 0.0f, 1.0f, 0.0f ) ); glfwSetWindowUserPointer( m_window, m_eventHandler ); m_eventHandler->setCallbacks(); Creation of the input handler during window creation. For now, the camera is part of the input handler, hence the two vectors (position, up-vector).  In future i'll take that functionally out into an own class that inherits from the event handler.
      void EventHandler::setCallbacks() { glfwSetCursorPosCallback( m_window->getWindow(), cursorPosCallback ); glfwSetKeyCallback( m_window->getWindow(), keyCallback ); glfwSetScrollCallback( m_window->getWindow(), scrollCallback ); glfwSetMouseButtonCallback( m_window->getWindow(), mouseButtonCallback ); } Set callbacks in the input handler.
      // static void EventHandler::cursorPosCallback( GLFWwindow *w, double x, double y ) { EventHandler *c = reinterpret_cast<EventHandler *>( glfwGetWindowUserPointer( w ) ); c->onMouseMove( (float)x, (float)y ); } Example for the cursor pos callback redirection to a class method.
      // virtual void EventHandler::onMouseMove( float x, float y ) { if( x != 0 || y != 0 ) { // @todo cursor should be set automatically, according to doc if( m_window->isCursorDisabled() ) glfwSetCursorPos( m_window->getWindow(), m_center.x, m_center.y ); // switch up/down because its more intuitive m_yaw += m_mouseSensitivity * ( m_center.x - x ); m_pitch += m_mouseSensitivity * ( m_center.y - y ); // to avoid locking if( m_pitch > 89.0f ) m_pitch = 89.0f; if( m_pitch < -89.0f ) m_pitch = -89.0f; // Update Front, Right and Up Vectors updateCameraVectors(); } } // onMouseMove() Mouse movement processor method. The interesting part is the manual reset of the mouse position that made the thing work ...
      // straight line distance between the camera and look at point, here (0,0,0) float distance = glm::length( m_target - m_position ); // Calculate the camera position using the distance and angles float camX = distance * -std::sin( glm::radians( m_yaw ) ) * std::cos( glm::radians( m_pitch) ); float camY = distance * -std::sin( glm::radians( m_pitch) ); float camZ = -distance * std::cos( glm::radians( m_yaw ) ) * std::cos( glm::radians( m_pitch) ); // Set the camera position and perspective vectors m_position = glm::vec3( camX, camY, camZ ); m_front = glm::vec3( 0.0, 0.0, 0.0 ) - m_position; m_up = m_worldUp; m_right = glm::normalize( glm::cross( m_front, m_worldUp ) ); glm::lookAt( m_position, m_front, m_up ); Orbiting camera vectors calculation in updateCameraVectors().
      Now, for my understanding, as the glfw manual explicitly states that if cursor is disabled then it is reset to the center, but my code only works if it is reset manually, i fear i am doing something wrong. It is not world moving (only if there is a world to render :-)), but somehow i am curious what i am missing.
       
      I am not a professional programmer, just a hobbyist, so it may well be that i got something principally wrong :-)
      And thanks for any hints and so ...
       
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