glsl

I am using freeglut, GLEW and DevIL to render a textured teapot using a vertex and fragment shader. This is all working fine in OpenGL 2.0 and GLSL 1.2 on Ubuntu 14.04. Now, I want to apply a bump map to the teapot. My lecturer evidently doesn't brew his own tea, and so doesn't know they're supposed to be smooth . Anyway, I found a nice-looking tutorial on old-school bump mapping that includes a fragment shader that begins: uniform sampler2D DecalTex; //The texture uniform sampler2D BumpTex; //The bump-map What they don't mention is how to pass two textures to the shader in the first place.

I'm doing ray casting in the fragment shader. I can think of a couple ways to draw a fullscreen quad for this purpose. Either draw a quad in clip space with the projection matrix set to the identity matrix, or use the geometry shader to turn a point into a triangle strip. The former uses immediate mode, deprecated in OpenGL 3.2. The latter I use out of novelty, but it still uses immediate mode to draw a point. You can send two triangles creating a quad, with their vertex attributes set to -1/1 respectively. You do not need to multiply them with any matrix in the vertex/fragment shader. Here

UPDATE: Because I needed something right away, I've created a simple shader wrapper that does the sort of thing I need. You can find it here: ShaderManager on GitHub . Note that it's designed for Objective-C / iOS, so may not be useful to everyone. If you have any suggestions for design improvements, please let me know! Original Problem: I'm new to using GLSL shaders. I'm familiar enough with the GLSL language and the OpenGL interface, but I'm having trouble designing a simple API through which to use shaders. OpenGL's C interface to interact with shaders seems cumbersome. I can't seem to find

I'm learning glsl shading and I've come across different file formats. I've seen people giving their vertex and fragment shaders .vert and .frag extensions. But I've also seen .vsh and .fsh extensions, and even both shaders together in a single .glsl file. So I'm wondering if there is a standard file format, or which way is the 'correct' one? There is no standard file extension for GLSL shaders. The most common ones are probably .vert and .frag , as these are the extensions that 3D Labs used in some of their tools. But that's about it for any form of standard extension. There's no official

Well making something transparent isn't that difficult, but i need that transparency to be different based on an object's curve to make it look like it isn't just a flat object. Something like the picture below. The center is more transparent than the sides of the cylinder, it is more black which is the background color. Then there is the bezel which seems to have some sort of specular lighting at the top to make it more shiny, but i'd have no idea how to go about that transparency in that case. Using the normals of the surface relative to the eye position to determine the transparency value?

I searched a lot but could not find if the following statements are legal in a #version 330 vertex shader: #define note_the_following_whitespaces 0x01 (layout location = 7) vec3 out ov; (layout location = 8) vec3 out rv; void main() { rv = vec3(1.0,2.0,3.0); ov = (1.0+rv)/2.0; gl_Position = [whatever]... } I'm referring particularly to the (1.0+rv) - the shader compiles fine on every nVidia card, but refuses to compile on ATI cards. Unfortunately I don't have the exact compilation result, I just know that the compilation was unsuccessful. http://www.opengl.org/registry/doc/GLSLangSpec.3.30.6

I'm using (Py)OpenGL to display 256 colors indexed images. I use a shader together with a 1D texture containing the palette. Here's the Fragment shader code : #version 330 uniform sampler2D texture; uniform sampler1D palette; void main() { vec2 uv = gl_TexCoord[0].xy; vec4 color = texture2D(texture, uv); gl_FragColor = texture1D(palette, color.a) ; } To avoid rounding errors, all MAG and MIN filters are set to NEAREST. The way I was seeing the texture coordinates for the 1D texture was : color 0 lies in interval [0 ; 1/256[ color 1 lies in interval [1/256 ; 2/256[ ... color 255 lies in