i'm trying simple texture splatting on ios opengl es 2.0 (ipad). I have 4 tiled textures in pvrt compressed atlas (2x2 tiles). 4 single textures on 4 texture units was terribly slow.
vertex shader:
attribute lowp vec4 position;
attribute lowp vec2 tex0;
varying lowp vec2 surfCoord;
uniform mat4 projection_modelview;
uniform lowp float uv_coef;
varying lowp vec2 texCoord1;
varying lowp vec2 texCoord2;
varying lowp vec2 texCoord3;
varying lowp vec2 texCoord4;
void main()
{
gl_Position = projection_modelview * position;
vec2 texCoord = fract(vec2(position.x / uv_coef, position.y / uv_coef));
texCoord1 = texCoord * 0.5;
texCoord2 = texCoord1 + vec2(0.5, 0);
texCoord3 = texCoord1 + vec2(0, 0.5);
texCoord4 = texCoord1 + vec2(0.5, 0.5);
surfCoord = tex0;
}
fragment shader:
uniform sampler2D texture0; // surface alpha map
uniform sampler2D texture1; // atlas
varying lowp vec2 surfCoord;
varying lowp vec2 texCoord1;
varying lowp vec2 texCoord2;
varying lowp vec2 texCoord3;
varying lowp vec2 texCoord4;
void main()
{
lowp vec4 surfTexel = texture2D(texture0, surfCoord);
lowp vec4 texel1 = texture2D(texture1, texCoord1);
lowp vec4 texel2 = texture2D(texture1, texCoord2);
lowp vec4 texel3 = texture2D(texture1, texCoord3);
lowp vec4 texel4 = texture2D(texture1, texCoord4);
texel1 *= surfTexel.r;
texel2 = mix(texel1, texel2, surfTexel.g);
texel3 = mix(texel2, texel3, surfTexel.b);
gl_FragColor = mix(texel3, texel4, surfTexel.a);
}
shows this one:
(source: inputwish.com)
My problem is probably texture unit interpolators but i don't how to resolve. I don't see mistake in my shaders. Any advice please?
mistake is using fract in vertex shader. it's too early. It should be in fragment shader:
lowp vec4 texel1 = texture2D(texture1, fract(texCoord) * 0.5);
lowp vec4 texel2 = texture2D(texture1, fract(texCoord) * 0.5 + vec2(0.5, 0.0));
lowp vec4 texel3 = texture2D(texture1, fract(texCoord) * 0.5 + vec2(0.0, 0.5));
lowp vec4 texel4 = texture2D(texture1, fract(texCoord) * 0.5 + vec2(0.5, 0.5));
... and mix them together..
anyway it's slow because dependent texture reads on ipad ios.
Related
I am completely new to opengl es shader and cook-torrance,
the following shader only output red, no texture color processed for ambient light and point light.
the cube is for testing,no shader applied to it, the right side rocket with texture with no output,just red color. Any opengl es guy can help?
no texture only red
original texture before apply cook-torrance and output by gl_FragColor =texture2D(texture,vertTexCoord.st).rgb*vertColor;
But what make CookTorance() below fail?
fragment shader
#ifdef GL_ES
precision mediump float;
precision mediump int;
#endif
#define PI 3.14159265
//copper
uniform vec3 diffuseColor = vec3(0.75164,0.60648,0.22648);
uniform vec3 specularColor = vec3(0.256777,0.137622,0.086014);
uniform float F0 = 0.8;
uniform float roughness = 0.1;
uniform float k = 0.2;
//uniform vec3 lightColor = vec3(1, 1, 1);
uniform sampler2D texture;
varying vec4 varyvertColor;
varying vec3 ecNormal; //eye normal
varying vec3 lightDir;
varying vec4 varyambient;
varying vec4 varyspecular;
varying float varyshininess; //0.1
varying vec4 vertTexCoord;
varying vec4 vposition;
vec3 CookTorrance(vec3 materialDiffuseColor,
vec3 materialSpecularColor,
vec3 normal,
vec3 lightDir,
vec3 viewDir,
vec3 lightColor)
{
float NdotL = max(0, dot(normal, lightDir));
float Rs = 0.0;
if (NdotL > 0)
{
vec3 H = normalize(lightDir + viewDir);
float NdotH = max(0, dot(normal, H));
float NdotV = max(0, dot(normal, viewDir));
float VdotH = max(0, dot(lightDir, H));
// Fresnel reflectance
float F = pow(1.0 - VdotH, 5.0);
F *= (1.0 - F0);
F += F0;
// Microfacet distribution by Beckmann
float m_squared = roughness * roughness;
float r1 = 1.0 / (4.0 * m_squared * pow(NdotH, 4.0));
float r2 = (NdotH * NdotH - 1.0) / (m_squared * NdotH * NdotH);
float D = r1 * exp(r2);
// Geometric shadowing
float two_NdotH = 2.0 * NdotH;
float g1 = (two_NdotH * NdotV) / VdotH;
float g2 = (two_NdotH * NdotL) / VdotH;
float G = min(1.0, min(g1, g2));
Rs = (F * D * G) / (PI * NdotL * NdotV);
}
return materialDiffuseColor * lightColor * NdotL + lightColor * materialSpecularColor * NdotL * (k + Rs * (1.0 - k));
}
void main(){
vec3 direction = normalize(lightDir);
//vec3 normal = normalize(ecNormal);
vec3 normal = -normalize(ecNormal);
vec4 vertColor = varyambient +
vec4(CookTorrance(texture2D(texture,vertTexCoord.st).rgb*varyvertColor.xyz,
varyspecular.xyz*specularColor,
vposition.xyz,
direction,
normal,
varyvertColor.rgb),1.0);
gl_FragColor = vertColor;
}
is there any error in the above cook-torrance?
please help on it.
the vertex shader
uniform mat4 modelviewMatrix;
uniform mat4 transformMatrix;
uniform mat3 normalMatrix;
uniform mat4 texMatrix;
attribute vec4 position;
attribute vec4 color;
attribute vec3 normal;
attribute vec4 ambient;
attribute vec4 specular;
attribute float shininess;
attribute vec2 texCoord;
varying vec4 vposition;
varying vec4 vertColor;
varying vec3 ecNormal;
varying vec3 lightDir;
varying vec4 varyambient;
varying vec4 varyspecular;
varying float varyshininess;
varying vec4 varyvertColor;
varying vec4 vertTexCoord;
void main() {
// Vertex in clip coordinates
gl_Position = transformMatrix * position;
vposition = transformMatrix * position;
// Vertex in eye coordinates
vec3 ecVertex = vec3(modelviewMatrix * position);
// Normal vector in eye coordinates
ecNormal = normalize(normalMatrix * normal);
varyambient=ambient;
varyspecular=specular;
varyshininess=shininess;
varyvertColor=color;
vertTexCoord = texMatrix * vec4(texCoord, 1.0, 1.0);
}
I have variable in vertex shader "uIsTeapot".
uniform float uIsTeapot;
Vertex shader work with it very well, but fragment shader don't see it. If I use
if (uIsTeapot == 0.0)
then an error occured
"uIsTeapot": undeclared identifier
but I defined it in vertex shader. If I define uIsTeapot in both shaders as uniform, then program say "Could not initialise shaders" since program don't pass veryfication
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
}
EDITED:
I add mediump to variables and now program compiled without errors, but result is one object on screen, but I draw two object.
Vertex shader
attribute vec3 aVertexPosition;
attribute vec3 aVertexNormal;
attribute vec2 aTextureCoord;
attribute vec4 aVertexColor;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
uniform mat3 uNMatrix;
uniform vec3 uAmbientColor;
uniform vec3 uPointLightingLocation;
uniform vec3 uPointLightingColor;
uniform mediump float uIsTeapot;
//varying float vIsTeapot;
varying vec2 vTextureCoord;
varying vec3 vLightWeighting;
varying vec4 vColor;
void main(void) {
if (uIsTeapot == 1.0) {
vec4 mvPosition = uMVMatrix * vec4(aVertexPosition, 1.0);
gl_Position = uPMatrix * mvPosition;
vec3 lightDirection = normalize(uPointLightingLocation - mvPosition.xyz);
vec3 transformedNormal = uNMatrix * aVertexNormal;
float directionalLightWeighting = max(dot(transformedNormal, lightDirection), 0.0);
directionalLightWeighting = 100.0;
vLightWeighting = uAmbientColor + uPointLightingColor * directionalLightWeighting;
vTextureCoord = aTextureCoord;
}
if (uIsTeapot == 0.0) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vColor = aVertexColor;
} }
Fragment shader
precision mediump float;
varying vec2 vTextureCoord;
varying vec3 vLightWeighting;
varying vec4 vColor;
uniform sampler2D uSampler;
uniform mediump float uIsTeapot;
//varying float vIsTeapot;
void main(void) {
if (uIsTeapot == 1.0) {
vec4 textureColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
gl_FragColor = vec4(textureColor.rgb * vLightWeighting, textureColor.a);
} else {
gl_FragColor = vColor;
}
}
You need to declare it in both shaders, with the same precision.
What do you mean by:
then program don't work right.
Can you post your vertex shader and your fragment shader? I suspect you are relying on the default precision, and it is likely that you are using highp in the vertex shader and mediump in the fragment shader
Try using:
uniform mediump float uIsTeapot;
... in both vertex shader and fragment shader.
I'm very new to OpenGL, GLSL and WebGL. I'm trying to get this sample code to work in a tool like http://shdr.bkcore.com/ but I can't get it to work.
Vertex Shader:
void main()
{
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
gl_TexCoord[0] = gl_MultiTexCoord0;
}
Fragment Shader:
precision highp float;
uniform float time;
uniform vec2 resolution;
varying vec3 fPosition;
varying vec3 fNormal;
uniform sampler2D tex0;
void main()
{
float border = 0.01;
float circle_radius = 0.5;
vec4 circle_color = vec4(1.0, 1.0, 1.0, 1.0);
vec2 circle_center = vec2(0.5, 0.5);
vec2 uv = gl_TexCoord[0].xy;
vec4 bkg_color = texture2D(tex0,uv * vec2(1.0, -1.0));
// Offset uv with the center of the circle.
uv -= circle_center;
float dist = sqrt(dot(uv, uv));
if ( (dist > (circle_radius+border)) || (dist < (circle_radius-border)) )
gl_FragColor = bkg_color;
else
gl_FragColor = circle_color;
}
I figured that this code must be from an outdated version of the language, so I changed the vertex shader to:
precision highp float;
attribute vec2 position;
attribute vec3 normal;
varying vec2 TextCoord;
attribute vec2 textCoord;
uniform mat3 normalMatrix;
uniform mat4 modelViewMatrix;
uniform mat4 projectionMatrix;
varying vec3 fNormal;
varying vec3 fPosition;
void main()
{
gl_Position = vec4(position, 0.0, 1.0);
TextCoord = vec2(textCoord);
}
That seemed to fix the error messages about undeclared identifiers and not being able to "convert from 'float' to highp 4-component something-or-other", but I have no idea if, functionally, this will do the same thing as the original intended.
Also, when I convert to this version of the Vertex Shader I have no idea what I'm supposed to do with this line in the Fragment Shader:
vec2 uv = gl_TexCoord[0].xy;
How do I convert this line to fit in with the converted vertex shader and how can I be sure that the vertex shader is even converted correctly?
gl_TexCoord is from desktop OpenGL, and not part of OpenGL ES. You'll need to create a new user-defined vec2 varying to hold the coordinate value.
I've been trying to implement a basic fog function, and some resources I've found have led me to try a linear fog function that my understanding has led me to believe is based on the original fixed function fog equation (though I could be wrong on that). However, when I try to implement it, all my surfaces become black. I'm pretty sure my problem lies in how I (attempt to) compute the eye distance, as the rest of the equation is pretty straightforward.
My vertex shader:
precision mediump float;
attribute vec4 position;
attribute vec3 normal;
attribute vec2 texCoordIn;
varying vec3 eyeNormal;
varying vec4 eyePos;
varying vec2 texCoordOut;
varying float eyeDistance;
uniform mat4 modelViewProjectionMatrix;
uniform mat4 modelViewMatrix;
uniform mat3 normalMatrix;
uniform vec3 cameraPosition;
void main()
{
eyeNormal = (normalMatrix * normal);
eyePos = modelViewMatrix * position;
eyeDistance = sqrt((eyePos.x - cameraPosition.x) * (eyePos.x - cameraPosition.x) + (eyePos.y - cameraPosition.y) * (eyePos.y - cameraPosition.y) + (eyePos.z - cameraPosition.z) * (eyePos.z - cameraPosition.z));
texCoordOut = texCoordIn;
gl_Position = modelViewProjectionMatrix * position;
}
My fragment shader:
precision mediump float;
varying vec3 eyeNormal;
varying vec4 eyePos;
varying vec2 texCoordOut;
varying float eyeDistance;
uniform sampler2D texture;
uniform vec3 flashlightPosition;
uniform vec3 diffuseLightPosition;
uniform vec4 diffuseComponent;
uniform float shininess;
uniform vec4 specularComponent;
uniform vec4 ambientComponent;
uniform float maxFogDistance;
uniform float minFogDistance;
uniform vec4 fogColor;
void main()
{
vec4 ambient = ambientComponent;
vec3 N = normalize(eyeNormal);
float nDotVP = max(0.0, dot(N, normalize(diffuseLightPosition)));
vec4 diffuse = diffuseComponent * nDotVP;
vec3 E = normalize(-eyePos.xyz);
vec3 L = normalize(flashlightPosition - eyePos.xyz);
vec3 H = normalize(L+E);
float Ks = pow(max(dot(N, H), 0.0), shininess);
vec4 specular = Ks*specularComponent;
if( dot(L, N) < 0.0 ) {
specular = vec4(0.0, 0.0, 0.0, 1.0);
}
float factor = (maxFogDistance - eyeDistance) / (maxFogDistance - minFogDistance);
factor = clamp(factor, 0.0, 1.0);
vec4 finalFogColor = factor * fogColor;
vec4 finalColor = (ambient + specular) * texture2D(texture, texCoordOut);
gl_FragColor = finalColor * factor + fogColor * (1.0 - factor);
gl_FragColor.a = 1.0;
}
Additionally, the minimum fog distance has been set to 1f and the maximum to 10f (my movement space is quite small, currently 5x5, so this should be appropriate) and the fog color is set to white.
Any help anybody could provide would be much appreciated. I can post additional code if the problem isn't in the shaders (though, I can't figure anywhere else it would be, the other aspects of the shaders worked fine before this).
I have been working in a skull with opengl es 2.0. The skull appeared without some faces:
After that I dedided to disable gl_cull_face. The problem with the faces was
solved but the the skull appears now without light and I haven´t changed shader code:
I have tried with other lighting algorithms and the skull continues black. I can't understand what is the relationship between gldisable(gl_cull_face) and lighting. The shader code is this:
Vertex Shader:
uniform mediump mat4 MODELVIEWMATRIX;
uniform mediump mat4 PROJECTIONMATRIX;
uniform mediump mat3 NORMALMATRIX;
uniform mediump vec3 LIGHTPOSITION;
varying lowp vec3 lightcolor;
attribute mediump vec3 POSITION;
attribute lowp vec3 NORMAL;
lowp vec3 normal;
attribute mediump vec2 TEXCOORD0;
varying mediump vec2 texcoord0;
void main( void ) {
mediump vec3 position = vec3( MODELVIEWMATRIX * vec4( POSITION, 1.0 ) );
normal = normalize( NORMALMATRIX * NORMAL );
mediump vec3 lightdirection = normalize( LIGHTPOSITION - position );
lowp float ndotl = max( dot( normal, lightdirection ), 0.0 );
lightcolor = ndotl * vec3( 1.0 );
gl_Position = PROJECTIONMATRIX * vec4( position, 1.0 );
texcoord0 = TEXCOORD0;
}
Fragment Shader:
varying mediump vec2 texcoord0;
uniform sampler2D DIFFUSE;
varying lowp vec3 lightcolor;
void main( void ) {
gl_FragColor = texture2D( DIFFUSE, texcoord0 ) * vec4( lightcolor, 1.0 ) + vec4( 0.1);
}
Thank you.