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• By lxjk
Hi guys,
There are many ways to do light culling in tile-based shading. I've been playing with this idea for a while, and just want to throw it out there.
Because tile frustums are general small compared to light radius, I tried using cone test to reduce false positives introduced by commonly used sphere-frustum test.
On top of that, I use distance to camera rather than depth for near/far test (aka. sliced by spheres).
This method can be naturally extended to clustered light culling as well.
The following image shows the general ideas

Performance-wise I get around 15% improvement over sphere-frustum test. You can also see how a single light performs as the following: from left to right (1) standard rendering of a point light; then tiles passed the test of (2) sphere-frustum test; (3) cone test; (4) spherical-sliced cone test

I put the details in my blog post (https://lxjk.github.io/2018/03/25/Improve-Tile-based-Light-Culling-with-Spherical-sliced-Cone.html), GLSL source code included!

Eric

• Good evening everyone!

I was wondering if there is something equivalent of  GL_NV_blend_equation_advanced for AMD?
Basically I'm trying to find more compatible version of it.

Thank you!

• Hello guys,

How do I know? Why does wavefront not show for me?
I already checked I have non errors yet.

And my download (mega.nz) should it is original but I tried no success...
- Add blend source and png file here I have tried tried,.....

PS: Why is our community not active? I wait very longer. Stop to lie me!
Thanks !

• I wasn't sure if this would be the right place for a topic like this so sorry if it isn't.
I'm currently working on a project for Uni using FreeGLUT to make a simple solar system simulation. I've got to the point where I've implemented all the planets and have used a Scene Graph to link them all together. The issue I'm having with now though is basically the planets and moons orbit correctly at their own orbit speeds.
I'm not really experienced with using matrices for stuff like this so It's likely why I can't figure out how exactly to get it working. This is where I'm applying the transformation matrices, as well as pushing and popping them. This is within the Render function that every planet including the sun and moons will have and run.
if (tag != "Sun") { glRotatef(orbitAngle, orbitRotation.X, orbitRotation.Y, orbitRotation.Z); } glPushMatrix(); glTranslatef(position.X, position.Y, position.Z); glRotatef(rotationAngle, rotation.X, rotation.Y, rotation.Z); glScalef(scale.X, scale.Y, scale.Z); glDrawElements(GL_TRIANGLES, mesh->indiceCount, GL_UNSIGNED_SHORT, mesh->indices); if (tag != "Sun") { glPopMatrix(); } The "If(tag != "Sun")" parts are my attempts are getting the planets to orbit correctly though it likely isn't the way I'm meant to be doing it. So I was wondering if someone would be able to help me? As I really don't have an idea on what I would do to get it working. Using the if statement is truthfully the closest I've got to it working but there are still weird effects like the planets orbiting faster then they should depending on the number of planets actually be updated/rendered.

• Hello everyone,
I have problem with texture

OpenGL avoid loosing Stacked Transformations on Load identity matrix

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Hi guys,

When I use to code in regular old opengl it had glLoadIdentity() which would help me translate my object , load Identity matrix and then rotate it around its own axis.

when stacking translation and rotation together an object will not rotate around its own origin, but rather (around the initial point it was translated from).(which according to matrix math it is supposed to)

How do I translate an object and then rotatate it about its own origin using glm library or even better manually since I want to understand how it can be done. I presume loadIdentity resets the model matrix to identity matrix but then you will loose your previous translation .. I cannot seem to figure out how you could do it manually here is my code:

RenderScene

void renderScene()
{
glm::mat4 ModelViewProject;

glm::mat4 View;

glm::mat4 Model;

glm::mat4 Projection = glm::perspective(45.0f, 1024.0f / 768.0f, 0.1f, 10.0f);

glm::mat4 rotation = glm::rotate(Model, angle, glm::vec3(1, 0, 0));

Model *= rotation;

glm::mat4 transRotation = glm::translate(rotation, glm::vec3(xCh, yCh, zCh));

Model *= transRotation;
View = glm::lookAt(glm::vec3(0, 0, 2), glm::vec3(0, 0, 0), glm::vec3(0.0, 1.0, 0.0));

ModelViewProject = Projection * View *  Model;

GLint transform = glGetUniformLocation(programId, "ModelViewProject");

glUniformMatrix4fv(transform, 1, false, glm::value_ptr(ModelViewProject));;

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glClearColor(0.0, 0.0, 0.0, 1.0);

glDrawArrays(GL_TRIANGLES, 0, 6);

glutSwapBuffers();
}



Vertex Initial position


void init()
{
int z = 1.0f;

GLfloat vertices[] =
{

0.999999f, 1.000000f, 1.0f,
0.0f, 0.0f, 1.0f,
-1.000000f, 1.000000f, 1.0f,
1.0f, 1.0f, 0.0f,
-1.000000f, -1.000000f, 1.0f,
0.0f, 1.0f, 1.0f, // colors

1.000000f, -1.000000f, 1.0f,
1.0f, 1.0f, 0.4f,
0.999999f, 1.000000f, 1.0f,
1.0f, 0.8f, 0.4f,
-1.000000f, -1.000000f, 1.0f,
0.7f, 0.8f, 0.4f,
};

GLint VertexId;

VertexId = glGetAttribLocation(programId, "position");

glEnable(GL_DEPTH_TEST);

GLuint myBuffId = 0;

glGenBuffers(1, &myBuffId);

glEnableVertexAttribArray(VertexId);

glBindBuffer(GL_ARRAY_BUFFER, myBuffId);

glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

glVertexAttribPointer(VertexId, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 6, 0);

glVertexAttribPointer(FragmentShaderColorId, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 6, (char *)(sizeof(float) * 3));  // stride of 5 floats describing my colors starting at position 2



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glm::mat4 translation = glm::translate(glm::mat4(1.0f), glm::vec3(x, y, z));
The mat4(1.0f) is an identity matrix so it leaves your rotation matrix intact

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Ok, when I try to multiply the translation with the (Model * View * Projection) and then the rotation with the translated (Model * View * Projection) it gives me the same result.

glm::mat4 ModelViewProject;

glm::mat4 View;

glm::mat4 Model;

glm::mat4 Projection = glm::perspective(45.0f, 1024.0f / 768.0f, 0.1f, 10.0f);

glm::mat4 translate = glm::translate(glm::mat4(1.0), glm::vec3(xCh, yCh, zCh));

Model *= translate;

glm::mat4 rotation = glm::rotate(glm::mat4(1.0), angle, glm::vec3(1, 0, 0));

Model *= rotation;

View = glm::lookAt(glm::vec3(0, 0, 2), glm::vec3(0, 0, 0), glm::vec3(0.0, 1.0, 0.0));

ModelViewProject = Projection * View *  Model;



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glm::mat4 translate = glm::translate(glm::mat4(1.0), glm::vec3(xCh, yCh, zCh));

Model *= translate;

glm::mat4 rotation = glm::rotate(glm::mat4(1.0), angle, glm::vec3(1, 0, 0));

Model *= rotation;

View = glm::lookAt(glm::vec3(0, 0, 2), glm::vec3(0, 0, 0), glm::vec3(0.0, 1.0, 0.0));

You have a lot of mix and match values here i dont know if it has been improved but glm never liked that so it might be worth changing your 1 to a 1.0f or a 1.f the same with your other numbers such as 0 and 2 to 0.0f and 2.0f

With matrix math aswell i believe the order is Scale * Rotation * Translation so in c++ it would be

model = translation * rotation * scale;

Then after doing that do your

modelViewProject = projection * view * model;

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Hi, thanks for your reply, I followed what you said, now the object rotates but still it rotates in an arc sort of way( yet less of an arc than before) but not around its own axis.
The most surprising thing is it rotates in an arc way even if you do not apply translation (just rotation).....any ideas ?

void renderScene()
{
glm::mat4 ModelViewProject(1.0f);

glm::mat4 View(1.0f);

glm::mat4 Model(1.0f);

glm::mat4 Projection = glm::perspective(45.0f, 1024.0f / 768.0f, 0.1f, 10.0f);

glm::mat4 translate = glm::translate(glm::mat4(1.0f), glm::vec3(xCh, yCh, zCh));

glm::mat4 rotation = glm::rotate(glm::mat4(1.0), angle, glm::vec3(1.0f, 0.0f, 0.0f));

Model = translate * rotation;

View = glm::lookAt(glm::vec3(0.0f, 0.0f, 2.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));

ModelViewProject = Projection * View *  Model;

GLint transform = glGetUniformLocation(programId, "ModelViewProject");

glUniformMatrix4fv(transform, 1, false, glm::value_ptr(ModelViewProject));;

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

glDrawArrays(GL_TRIANGLES, 0, 6);

glutSwapBuffers();
}