Opengl thicker lines. I'm new to OpenGL. After a quick search on google, it surprises Native line rendering in WebGL leaves a lot to be desired. My Specifies the width of rasterized lines. Anyway if you want to use a geometry shader, transform the vertex coordinate with the model view projection matrix in the vertex shader: #version 330 in vec4 a_position; uniform mat4 u_modelviewprojection_matrix; void main() { gl_Position = u The first line of the above shader specifies the shader language used, for OpenGL 3. Drawing a simple Picking in OpenGL is based on geometry. Are there any fast post-processing outline techniques that allow for thick outlines? For engine programmers, there are many cases you have to draw lines on screen, e. f, depending on the machine). Kind regards Alain When you draw a line in OpenGL, glLineWidth creates a fixed-size line, regardless how close the line is to you. Because that would result in generating two fragments in these cases, resulting in a thicker line than intended. Draw a quad over the entire viewport and discard any Hi, I’m making a program that draws lines by coloring in each pixel one at a time to form the line (using Bresenhan’s algorithm) and the line can have thickness from 1 to 15. opengles. I got it and I tried like that. I simply want to thicken one line using glLineWidth, Drawing a thick line with legacy OpenGL (immediate mode) in C++. I tryed to set glScissor(-width_of_line, -width_of_line, screen_width + width_of_line, screen_heigth + width_of_line) but lines are still cliped incorrecly. I develop with VC8. What I've already tried is to actually construct a poly with rounded joints like in this question's answer OpenGL doesn’t do joins or caps. . 3, Eighth Edition [Book] This is an example project that demonstrates how to draw thick and smooth lines / curves in 3D. In the OpenGL specification, line rasterization is defined by the 'diamond-exit' rule. Individual lines are therefore - Selection from OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4. Note how the connection between the Today I tried about a half-dozen of methods from shadertoy, to draw lines using a vertex-geometry-fragment shader, but none worked. 0f); does not have any effect on lines, and they remain just one pixel thick (even if I try a whole range of numbers). A “polyline” rendered with GL_LINE_STRIP or GL_LINE_LOOP is no different to rendering the individual I'm drawing a few lines using OpenGL ES and I need to change their thickness from 1 pixel to 3 pixels smoothly, but glLineWidth doesn't allow to set line thickness between If you are looking to draw thicker lines on a wireframe model you can use the wireframe example as a basis. I know how you can draw triangles using buffers, so I tried that with a line. The GL_LINES I am trying to implement geometry shader for line thickness using OpenGL 4. [Expected] I GL_LINE_STRIP: The adjacent vertices are considered lines. • Each bit represents a section of the line segment that is either on or off. This means if you [QUOTE=GClements;1292416]OpenGL doesn’t do joins or caps. • By default,each bit corresponds to a Lines, Strips, and Loops In OpenGL, the term line refers to a line segment, not the mathematician’s version that extends to infinity in both directions. rendering a grid on the ground, drawing bounding boxes and other helper objects. js, allowing line thicknesses of any size (THREE. It seems to be a limitation of the OpenGL Core Profil. However, I find no way to change how often the texture is repeated. I’m using 00x on both mac and PC. 9. Set glLineWidth() to 0. If you need thicker lines you can always emulate it via two triangles. Unfortunately, drawing lines is a weak point of OpenGL. I have also tried using a 128x128 texture version. GClements August 30, 2018, I want to draw a series of connected lines (GL_LINE_STRIP) in following way. So essentially the list of 2D points need to become a list of vertices specifying the outline of a The task is to generate thick line strip, with as less CPU and GPU overhead as possible. Hello, I’m trying to draw cube with lines which connects every single vertex on 3D space. I'm using OpenGl 4. A standard sobel filter with a 3x3 kernel gives outlines with a width of 2 pixels, and the kernel size can be increased to give thicker outlines, but an outline of 16 pixels with this method requires 225(?) texture samples per fragment. I have an array of all edges (lines) which are specified by two vertices. Drawing a line in modern OpenGL. Here's the result using a glLineWidth of 1 for comparison. That means to avoid computation of polygons on the CPU as well as geometry shaders (or This code results in the following mesh: For demonstration purposes, the generated mesh is once rendered in wireframe mode (light green), and once in fill mode (transparent green). Drawing Lines is Hard. the lines are a bit thicker on both The result with a line width of 1 is good enough: However, when I set a thicker line width (> 3), this happens: OpenGL render lines as quads, resulting in blank spaces between edges and a popping effect whenever the model is rotated. How to draw the outline of a thick line? 4. and I want lines that are actually visible to user to be drawn on the screen. Cumore October 15, 2007, 6:00pm 3. (there are many lines which come very close to each other, so at a width of 10 many of them overlap, but the artifacts are still present on lines with no near neighbors and at smaller widths). Follow It is seen that Cairo draws thin lines a little bit thicker than it should look. If shading mode is set to smooth, OpenGL will interpolate the colors along the line. (is not efficient using only the Fragment shader code! this is just for the test with 2. 6. By a brief benchmark, it is 30 times faster than OpenGL native line drawing with smoothing turned on. Is it possible in opengl to draw this type to triangles? I have already tried glBegin(GL_TRIANGLES); glBegin(GL_LINE_LOOP); Code and Result i got using glBegin(GL_LINE_LOOP) Code: glBegin( Hello! I’m writing a function that draws thick dashed lines with OpenGL. One needs some kind of tie-breaking rule, and the formulation chosen in the GL spec is just that. A “polyline” rendered with GL_LINE_STRIP or GL_LINE_LOOP is no different to rendering the individual line segments separately. edges) in OpenGL. Everything is ok. You can change the line width with glLineWidth() I'm looking for a way to draw lines with thickness and smoothness with OpenGL ES2 without using the build it glLineWidth function which has a lot of limitations. Note This is forked from three. glLineWidth specifies the rasterized width of both aliased and antialiased lines. I’m guessing you’ve left out the calculation for n12 for brevity, but if that suggestion doesn’t work, 6. Using a line width other than 1 has different effects, depending on whether line antialiasing is A thick line can be easily implemented by creating a tri-strip along the path, where every pair of points (one “above” the line, one “below”) is displaced by +/- a displacement I am trying to draw a skeleton of a cube (i. 2 the corresponding shader language version is 1. glPointSize(5. I am able to render a If you want to draw a thick smooth line, you have 3 options: Draw a highly tessellated polygon with many vertices. Maps are mostly made up of lines, as well as the occasional polygon thrown in. Next, we have a global variable of type vec4 that will receive the position of a vertex, a GLSL vector that can store 4 values, by default this is initialized with (0,0,0,1). If you need "lines" with a thickness that changes with the camera distance, you will have to draw them as polygons. That means to avoid computation of polygons on the CPU as well as geometry shaders (or tessellation shaders). The line should be rendered in OpenGL (using OSG) as triangles. The red Description. There is no March 9, 2015. I followed accepted answer and other given solutions of stackoverflow, but it is wrong according \$\begingroup\$ +1 - this is the most straightforward approach. And 40 times faster than Cairo when rasterization is heavy (e. It all seems to work until I try to change the line thickness of the I simply want to draw a line to the screen. I had tried to code by my own, but not get desired result, so i come here, help me to find out where i was wrong. If you want joins or caps, you’ll need to render them yourself. It is known that the native GL_LINE_STRIP_ADJACENCY creates gaps when drawing a polyline. Line width and point size are rasterization parameters A good and fast solution based on my Rasterizer library that uses Wu's algorithm for thin lines (xmin,ymin,xmax,ymax are the boundaries of the viewport used for clipping). Do the lines on my texture just need to be thicker? Provides a Mesh-based replacement for THREE. Then draw lines using glDrawArrays (or Elements if your data is indexed) with mode=GL_LINES or one of the other line drawing modes. After great efforts I have ensured that the geometry of the texture suits well to the line (drawn with triangle strips). If the user only specifies 1 vertex, the drawing command is By Konstantin Käfer. Getting good The cell shading approach (drawing extruded back face mesh) might be easier and look better, even if the lines become thinner on a corner than on an edge. I am able to render a I want to turn these into a strip of triangles in order to render a textured line with a specified thickness (and other such things). 0 in pocket PC, i want to get wider lines using glLinewidth(), but its width is always 1. Imagine a highway which is being constructed. Imagine a highway which is being 3. Khronos Forums How to draw a smooth thick polyline? OpenGL. I think this can be done using shaders, but my glsl skills are limited. The version of this starts at 2. I think it is just A possible solution without using a geometry shader is presented in the answer to OpenGL Line Width. It depends on the country, company, etc, but This code results in the following mesh: For demonstration purposes, the generated mesh is once rendered in wireframe mode (light green), and once in fill mode (transparent green). If you want your lines be thicker on near end and thinner on far end, I suppose you have to model them from polygons. e. Note that since the user is talking about line drawing in 3d, the 'thick lines' should actually be cylinders and the Note: This first option is no longer a valid solution since the latest OpenGL versions no longer support line thickness either. Provide details and share your research! But avoid . After reading up Drawing a thick line with legacy OpenGL (immediate mode) in C++ (1 answer) Closed 2 years ago. Another restriction of the above mode is that thickness cannot surpass certain threshold (e. I have a 3D CAD-like application for which I use OpenGL wrapper library (OpenSceneGraph). Usually it’s not a problem if you are very used to the jaggies, but recently I can’t stand it anymore, my eyes complain to me that they want anti-aliased lines. glLineWidth(desired_line_size) If you require lines of varying The red color line is drawn by using OpenGL default GL_LINE_STRIP, while the greenish line is drawn by using the shader program. glGetFloatv(GL_LINE_WIDTH_RANGE,sizes); One crazy idea is to use a cylinder for drawing lines ;). Share. Dude, 1. Here I explore The bottom line is that OpenGL abandoned lines thicker than one pixel, and given the advent of high-dpi displays that makes line drawing less useful with only 1 pixel lines. Cumore October 15, 2007, 12:11am 1. The texture (see the attached image) is 4 pixels wide by 8 high. 1. Outlines can be accomplished by rendering a thick line with a slimmer line on top, using the same data set for each. The initial value is 1. The OpenGL is very good at drawing points, lines, and triangles, and hardware accelerating certain common operations such as clipping, face culling, perspective divides, So I have an application with a wireframe type draw and I was wondering if anyone has any useful tips/hints on doing really good line Anti-Aliasing with basic OpenGL? Currently I Enable GL_MULTISAMPLE. The real You can clip the line at z=0, or just punt and divide by abs (w) instead. Line is limited to 1 pixel width), and other features. It didn't work, Line Stippling • In addition to changing line widths, you can create lines with a dotted or dashed pattern, called stippling • The pattern parameter is a 16-bit value that speciﬁes a pattern to Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. So I'm trying to (what I think would be simply) draw the outline of a number of 2D shapes using OpenGL. I have a list of points (3D) and want to draw a line connecting all points with a specified width. Hello, Nils. 50. Nils. Apr 18, 2017 1 min read. 0f) works perfectly, and enabling GL_LINE_SMOOTH doesn’t seem to make any difference other than slightly thicker OpenGL draws lines at a fixed width measured in pixels, independent of the distance from the camera. 0 because it modernizes the code base in ways that make it a breaking change, and removes deprecated First, set use the shaderprogram. The task is to generate thick line strip, with as less CPU and GPU overhead as possible. If I understood your question wrong then maybe you can Now the lines need to be . Render the thick line in the I have a problem with thick lines - they are cliped incorrectly, as if they were 1 pixel width. Help! I’ve been trying to sort out this problem for ages, and I am not getting anywhere! It seems that glLineWidth(5. This code demonstrates how a GLSL shaders can help to OpenGL. for each (x, y) position along the sin wave, emit two vertices, the same x but y = 0 (the bottom). gl. Enable GL_LINE_SMOOTH. There’s inconsistency in the implementation, so you can’t trust that the line width you want will be available to you, for example. This is accomplished through pyglet like so: pyglet. I use it when I want to have nice and controllable lines but I am not aware of a handy OpenGl function to do so. Twitter: @mattdesl. One of the main challenges consists in drawing thick dashed lines (roads, e. , 10. meshline, as that project has been dormant. g). Drawing lines might not sound like rocket science, but it’s damn difficult to do well in OpenGL, particularly WebGL. Not sure. If an object intersects the clip volume after transformations, a hit is recorded. Obviously the flaw is with my software. Description In OpenGL 1. For the application I am trying to come up with the best strategy on how Therefore, I have to render complicated maps. b) as it is a 3d application, they basically must have an cylindrical shape (It would look very weird otherwise). Also, since δ and ϵ are positive, does To tessellate the above, specify a top then a bottom vertex right along the line, then draw a triangle strip. Check also @gman his answer. I wanted to draw a line that will appear bigger when it's close. a) thick lines and . Improve this answer. OpenGL: Basic Coding. The MeshLine Class looks very promising (very smooth lines) but I have no idea how to “transform” the imported geometry into this nice looking lines (and how to ignore triangles on flat surfaces). g. The red points show the input points. 3. To draw a line in Fragment Shader, we should check that the current pixel (UV) is on the line position. If anybody could guide me to the right direction . Thus, if you pass n vertices, you will get n-1 lines. here i am giving only my draw() function. Each segment of the The default OpenGL drawing of line strip geometry does not allow to render smooth (non-broken) lines, as well as to render them of customary thicker than default width: One of the ways to solve the problem is to represent Description. Hi. Line from Three. 5 Enable GL_BLEND (with standard blend function) Set glDepthMask to FALSE Set glHint to Line Stippling • In addition to changing line widths, you can create lines with a dotted or dashed pattern, called stippling • The pattern parameter is a 16-bit value that speciﬁes a pattern to use when drawing the lines. Modern opengl (core profile), the line width is limited by system. All tutorials I found used a glVertexPointer, which is deprecated as far as I can tell. Using a line width other than 1 has different effects, depending on whether line antialiasing is I am trying to draw a skeleton of a cube (i. The thinest part of the white lines are only a couple of pixels thick. In order to draw a free width line smooth, we draw multiple One of the main challenges consists in drawing thick dashed lines (roads, e. i. Here's a code example for 2D lines with different color in each end. How can I make OpenGL clip thick lines correctly? Clarifying Differences in Line Rendering Between OpenGL and DX12 I’d like to clarify some points regarding the visual differences in line rendering between the old OpenGL engine and the modern DX12 engine, especially focusing on anti-aliasing (AA) and driver settings. 2, the tokens GL_LINE_WIDTH_RANGE and GL_LINE_WIDTH_GRANULARITY You can change the width of lines by calling glLineWidth. , drawing 10000 thick lines). Asking for help, clarification, Draw thick lines in opengl core profile. Also, these weird The problem is more obvious with thicker lines (screenshots above used glLineWidth of 10).

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Opengl thicker lines. My … Specifies the width of rasterized lines.