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Questions tagged [geometry-shader]

Geometry shader should not be mixed up with [vertex-shader], but are shader programs executed after vertex shaders. They take as input a whole primitive like point, line or triangle.

Geometry shaders are the 3rd type of GPU shader programs after and and process whole primitives like points, lines or triangles.

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232 questions
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Passing Data Through GLSL Shaders

I'm having some trouble passing data through my shaders, notably the Geometry shader. I've never used a Geometry Shader before so I'm having a little trouble understanding the way it passes data. Basically, before the Geometry shader, I'd pass data…
Seagull
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Screen-space distance along line strip in GLSL

When rendering a line strip, how do I get the distance of a fragment to the start point of the whole strip along the line in pixels? When rendering a single line segment between two points in 3D, the distance between those two points in screen space…
mOfl
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GLSL EndPrimitive() breaks triangle strip

I'm experimenting with geometry shaders on a Macbook Pro with Intel HD 4000 graphics running Mavericks. I'm noticing some odd behavior from an EndPrimitive() call. Here's my geometry shader: #version 150 core layout(points)…
anthonyvd
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opengl Draw Oval not Circle

if I call the function DrawFilledCircleo() it makes an oval and not a circle , even if i put glBegin(GL_LINE_LOOP); it always makes Oval void drawFilledCircle(GLfloat x, GLfloat y, GLfloat radius){ int i; int triangleAmount = 20; //# of…
NPLS
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Geometry shader, MaxVertexCount cannot be known

I am currently working on a shader where the amount of vertices are not defined by the amount of triangles, my shader puts a cuber every X units. This means that I cannot know in advance how many cubes it will create and I do not know many vertices…
Subject009
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Pass-through geometry shader

I just started with OpenGL in conjunction with Qt. I try to use a geometry shader to change the width of lines, but even a simple pass-through geometry shader results in an empty screen. Here is (an excerpt of) my…
user2970139
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Is it possible to draw a sphere with strands using a unique geometry shader?

I'd like to display a simple UV sphere (exported from Blender) and generate lines with normal coordinates using a unique geometry shader. In a first time, I wrote a simple geometry shader which simply return the input vertices informations to the…
user1364743
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How can I find the interpolated position between 4 vertices in a fragment shader?

I'm creating a shader with SharpDX (DirectX11 in C#) that takes a segment (2 points) from the output of a Vertex Shader and then passes them to a Geometry Shader, which converts this line into a rectangle (4 points) and assigns the four corners a…
c4sh
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Calculate Normals Geometry Shader

Im currently writing my own GLSL shaders, and wanted to have smooth shading. The shading worked when i calculated the normals bevore sending them to a VBO, but the problem here is when I implement animations with bone matricies, the normals are not…
Leo
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Rotating verticies created by a geometry shader

I am trying to generate a cube from 6 points (each point representing a side, then 2 extra values to say if its rotated to face on the x, or y axis, z axis doesn't need one because its like that by default). Problem comes in when I try to multiply…
Lemon Drop
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GLSL How to show normals with Geometry shader?

I have vertex shader #version 330 core layout(location = 0) in vec3 VertexPosition; layout(location = 1) in vec2 VertexUV; layout(location = 2) in vec3 VertexNormal; out VS_GS_VERTEX { vec2 UV; vec3 vs_worldpos; vec3 vs_normal; }…
user2091150
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How come I pass thru more vertices than I can generate in GLSL Geometry Shaders?

How come I can pass my geometry shader N (where N is a very high number, like 10000) vertices and render them like this: for (int i = 0; i < gl_VerticesIn; ++i) { gl_Position = projectionmodelview_matrix_ * gl_PositionIn[i]; …
Viktor Sehr
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corrupted primitives out of geometry shader opengl 3.2 GLSL 150

I have a simple geometry shader which I am using to calculate per face normals. VertexShader #version 150 in vec3 in_Position; uniform mat4 modelMat; uniform vec3 scale; void main(void) { // scale the verts vec3 scaledPosition = vec3(…
B_o_b
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generate vertices using geometry shader(GLSL)

recently I'm trying to implement an algorithm to generate vine in real time. I kinda know how to do it on cpu, but I want to use GPU to accomplish this. I was thinking of geometry shader, but it looks like geometry shader executes in primitive…
Nowibananatzki
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GLSL geometry value changing when it shouldnt

I'm working with a VERY simple program that is passing an array of points into the programable pipline to draw a cube. I'm trying to set it up so I can change the geometry every frame (based on some external input) and as such, for lighting, I need…
APalmer
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