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Shader problems
Dear Shader Experts
For an outdoor scene I am trying to get a vertex / fragment shader bundle working that allows for rendering a dynamic sky model. The project can be found here: https://github.com/kosua20/opengl-skydome While I have basic knowledge of GLSL and shaders I am having a hard time to get this running. In fact, when I import the sky sphere and apply the shaders, the sphere gets transparent, i.e. disappears. I assume that the problem might have to do with a missing uniform. For example, I am not sure whether it is possible to submit my uniforms as "vizmat" variables as I currently do for "mvp" and "star_pos" I attach my code together with the vertex and fragment shaders below. I really appreciate any kind of help! :-) Many thanks, Andreas ################ PYTHON CODE ################ import viz import vizfx import vizcam viz.setMultiSample(4) viz.go() logo = vizfx.addChild('logo.osgb') cam = vizcam.PivotNavigate(distance=3.5) cam.centerNode(logo) # add sky sphere mySphere = viz.add('sphere.obj') # import textures tint = viz.add('./img/tint.tga') tint2 = viz.add('./img/tint2.tga') sun = viz.add('./img/sun.tga') moon = viz.add('./img/moon.tga') clouds1 = viz.add('./img/clouds1.tga') clouds2 = viz.add('./img/clouds2.tga') # apply textures to buffers mySphere.texture(tint,'',0) mySphere.texture(tint2,'',1) mySphere.texture(sun,'',2) mySphere.texture(moon,'',3) mySphere.texture(clouds1,'',4) mySphere.texture(clouds2,'',5) # import shaders myVert = viz.addVertexProgram('skydome_vshader.glsl') myFrag = viz.addFragmentProgram('skydome_fshader.glsl') # apply shaders to sphere mySphere.apply(myVert) mySphere.apply(myFrag) # Use static clip plane so projection matrix doesn't change viz.MainWindow.clip(0.1,100) m = viz.MainWindow.getProjectionMatrix() # assign uniforms to shaders starPos = vizmat.Transform() starPos.makeEuler(0,0,0) sunPos = viz.addUniformFloat('sun_pos', [0,1,0]) mvp = viz.addUniformMatrix('mvp', m) time = viz.addUniformFloat('time', 0) weather = viz.addUniformFloat('weather', 0.5) starPos = viz.addUniformMatrix('star_pos', starPos) mySphere.apply(sunPos) mySphere.apply(mvp) mySphere.apply(time) mySphere.apply(weather) mySphere.apply(starPos) # update sky model based on current time stamp def ontimer(num): time=viz.addUniformFloat('time', viz.FRAME_TIMESTAMP) mySphere.apply(time) #sky_vp.param(0,viz.get(viz.FRAME_TIMESTAMP)*CLOUD _SPEED) viz.callback(viz.TIMER_EVENT,ontimer) viz.starttimer(0,0,viz.FOREVER) # add some ground ground = viz.add('tut_ground.wrl') ground.setPosition(0,-5,0) ################ VERTEX SHADER ################ #version 330 core //---------IN------------ in vec3 vpoint; in vec3 vnormal; //---------UNIFORM------------ uniform vec3 sun_pos;//sun position in world space uniform mat4 mvp; uniform mat3 rot_stars;//rotation matrix for the stars //---------OUT------------ out vec3 pos; out vec3 sun_norm; out vec3 star_pos; //---------MAIN------------ void main(){ gl_Position = mvp * vec4(vpoint, 1.0); pos = vpoint; //Sun pos being a constant vector, we can normalize it in the vshader //and pass it to the fshader without having to re-normalize it sun_norm = normalize(sun_pos); //And we compute an approximate star position using the special rotation matrix star_pos = rot_stars * normalize(pos); ################ FRAGMENT SHADER ################ #version 330 core //---------IN------------ in vec3 pos; in vec3 sun_norm; in vec3 star_pos; //---------UNIFORM------------ uniform sampler2D tint;//the color of the sky on the half-sphere where the sun is. (time x height) uniform sampler2D tint2;//the color of the sky on the opposite half-sphere. (time x height) uniform sampler2D sun;//sun texture (radius x time) uniform sampler2D moon;//moon texture (circular) uniform sampler2D clouds1;//light clouds texture (spherical UV projection) uniform sampler2D clouds2;//heavy clouds texture (spherical UV projection) uniform float weather;//mixing factor (0.5 to 1.0) uniform float time; //---------OUT------------ out vec3 color; //---------NOISE GENERATION------------ //Noise generation based on a simple hash, to ensure that if a given point on the dome //(after taking into account the rotation of the sky) is a star, it remains a star all night long float Hash( float n ){ return fract( (1.0 + sin(n)) * 415.92653); } float Noise3d( vec3 x ){ float xhash = Hash(round(400*x.x) * 37.0); float yhash = Hash(round(400*x.y) * 57.0); float zhash = Hash(round(400*x.z) * 67.0); return fract(xhash + yhash + zhash); } //---------MAIN------------ void main(){ vec3 pos_norm = normalize(pos); float dist = dot(sun_norm,pos_norm); //We read the tint texture according to the position of the sun and the weather factor vec3 color_wo_sun = texture(tint2, vec2((sun_norm.y + 1.0) / 2.0,max(0.01,pos_norm.y))).rgb; vec3 color_w_sun = texture(tint, vec2((sun_norm.y + 1.0) / 2.0,max(0.01,pos_norm.y))).rgb; color = weather*mix(color_wo_sun,color_w_sun,dist*0.5+0.5) ; //Computing u and v for the clouds textures (spherical projection) float u = 0.5 + atan(pos_norm.z,pos_norm.x)/(2*3.14159265); float v = - 0.5 + asin(pos_norm.y)/3.14159265; //Cloud color //color depending on the weather (shade of grey) * (day or night) ? vec3 cloud_color = vec3(min(weather*3.0/2.0,1.0))*(sun_norm.y > 0 ? 0.95 : 0.95+sun_norm.y*1.8); //Reading from the clouds maps //mixing according to the weather (1.0 -> clouds1 (sunny), 0.5 -> clouds2 (rainy)) //+ time translation along the u-axis (horizontal) for the clouds movement float transparency = mix(texture(clouds2,vec2(u+time,v)).r,texture(clou ds1,vec2(u+time,v)).r,(weather-0.5)*2.0); // Stars if(sun_norm.y<0.1){//Night or dawn float threshold = 0.99; //We generate a random value between 0 and 1 float star_intensity = Noise3d(normalize(star_pos)); //And we apply a threshold to keep only the brightest areas if (star_intensity >= threshold){ //We compute the star intensity star_intensity = pow((star_intensity - threshold)/(1.0 - threshold), 6.0)*(-sun_norm.y+0.1); color += vec3(star_intensity); } } //Sun float radius = length(pos_norm-sun_norm); if(radius < 0.05){//We are in the area of the sky which is covered by the sun float time = clamp(sun_norm.y,0.01,1); radius = radius/0.05; if(radius < 1.0-0.001){//< we need a small bias to avoid flickering on the border of the texture //We read the alpha value from a texture where x = radius and y=height in the sky (~time) vec4 sun_color = texture(sun,vec2(radius,time)); color = mix(color,sun_color.rgb,sun_color.a); } } //Moon float radius_moon = length(pos_norm+sun_norm);//the moon is at position -sun_pos if(radius_moon < 0.03){//We are in the area of the sky which is covered by the moon //We define a local plane tangent to the skydome at -sun_norm //We work in model space (everything normalized) vec3 n1 = normalize(cross(-sun_norm,vec3(0,1,0))); vec3 n2 = normalize(cross(-sun_norm,n1)); //We project pos_norm on this plane float x = dot(pos_norm,n1); float y = dot(pos_norm,n2); //x,y are two sine, ranging approx from 0 to sqrt(2)*0.03. We scale them to [-1,1], then we will translate to [0,1] float scale = 23.57*0.5; //we need a compensation term because we made projection on the plane and not on the real sphere + other approximations. float compensation = 1.4; //And we read in the texture of the moon. The projection we did previously allows us to have an undeformed moon //(for the sun we didn't care as there are no details on it) color = mix(color,texture(moon,vec2(x,y)*scale*compensatio n+vec2(0.5)).rgb,clamp(-sun_norm.y*3,0,1)); } //Final mix //mixing with the cloud color allows us to hide things behind clouds (sun, stars, moon) color = mix(color,cloud_color,clamp((2-weather)*transparency,0,1)); } |
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