GLSL ES equivalent to OpenGL GLSL 'out' keyword? - ios
I have a vertex shader which works fine on Windows with OpenGL. I want to use the same shader on an iPad which supports OpenGL ES2.0.
Compilation of the shader fails with:
Invalid storage qualifiers 'out' in global variable context
From what I have read, the 'out' keyword required GLSL 1.5 which the iPad won't support. Is there an equivalent keyword to 'out' that I can use to pass the color into my fragment shader?
attribute vec4 vPosition;
attribute vec4 vColor;
uniform mat4 MVP;
out vec4 pass_Color;
void main()
{
gl_Position = MVP * vPosition;
pass_Color = vColor;
}
This vertex shader is used by me to create gradient blends, so I'm assigning a color to each vertex of a triangle and then the fragment shader interpolates the color between each vertex. That's why I'm not passing a straight color directly into the fragment shader.
Solved! In GLSL ES 1.0 that I'm using, I need to use 'varying' instead of 'in' and 'out'. Here's the working shader:
attribute vec4 vPosition;
attribute vec4 vColor;
uniform mat4 MVP;
varying vec4 pass_Color;
void main()
{
gl_Position = MVP * vPosition;
pass_Color = vColor;
}
Related
Sampler3D in iOS
I have just include OpenGL ES 3.0 in my iOS app and it is working fine.
I have a working shader below:
#version 300 es
precision mediump float;
uniform sampler2D texSampler;
uniform float fExposure;
in vec2 fTexCoord;
in vec3 fColor;
out vec4 fragmentColor;
void main()
{
fragmentColor = texture(texSampler, fTexCoord) * vec4(fColor, 1.0) * fExposure;
}
Now, I want to use a sampler3D so I have:
#version 300 es
precision mediump float;
uniform sampler3D texSampler;
uniform float fExposure;
in vec3 fTexCoord;
in vec3 fColor;
out vec4 fragmentColor;
void main()
{
fragmentColor = texture(texSampler, fTexCoord) * vec4(fColor, 1.0) * fExposure;
}
and it doesn't compile. Also, I changed the vec2 texCoord to vec3 texCoord in the vertex shader.
Actually, sampler3D is not recognized, but as far as i know it exists in OpenGL ES 3.0.
Any ideas?
Similar to float, sampler3D does not have a default precision. Add this at the start of your fragment shader, where you also specify the default float precision: precision mediump sampler3D; Of course you can use lowp instead if that gives you sufficient precision. The only sampler types that have a default precision in ES 3.0/3.1 are sampler2D and samplerCube (both default to lowp). For all others, the precision has to be specified either as a default precision, or as part of the variable declaration.
Working with shaders using lookup data IOS
I have lookup data provided by one software and I want to use this data with shader as written below:
7999745,8000001,8000258,8066051,8066308,8132357,8132614,8198407,8198664,8264457,8264969,8330762,8331019,8396812,8397069,8463118,8463375,8529168,8529425,8595218,8595730,8661523,8661780,8727573,8727830,8793879,8794136,8859929,8860186,8925979,8926491,8992284,8992541,9058334,9058591,9059104,9124897,9125154,9190947,9191204,9257252,9257509,9323302,9323559,9389352,9389865,9455658,9455915,9521708,9521965,9588013,9588270,9654063,9654320,9720113,9720626,9786419,9786676,9852469,9852726,9918774,9919031,9984824,9985081,10050874,10051387,10117180,10117437,10183230,10183743,10183999,10249792,10250049,10315842,10316355,10382148,10382405,10448198,10448455,10514503,10514760,10580553,10580810,10646603,10647116,10712909,10713166,10778959,10779216,10845264,10845521,10911314,10911571,10977364,10977877,11043670,11043927,11109720,11109977,11176025,11176282,11242075,11242332,11308125,11308638,11308895,11374688,11374945,11440738,11441250,11507043,11507300,11573093,11573350,11639399,11639656,11705449,11705706,11771499,11772011,11837804,11838061,11903854,11904111,11970160,11970417,12036210,12036467,12102260,12102772,12168565,12168822,12234615,12234872,12300921,12301178,12366971,12367228,12433277,12433278,12433535,12433536,12433793,12499330,12499587,12499588,12499845,12565382,12565639,12565896,12565897,12566154,12631691,12631948,12631949,12632206,12697743,12698000,12698001,12698258,12698515,12764052,12764310,12764311,12764568,12830105,12830362,12830363,12830620,12830621,12896414,12896671,12896672,12896929,12962466,12962723,12962724,12962981,12962982,13028775,13028776,13029033,13029290,13094827,13095084,13095086,13095343,13095344,13161137,13161138,13161395,13161396,13227189,13227446,13227447,13227704,13227705,13293498,13293499,13293756,13293757,13359550,13359807,13359808,13360065,13360066,13425859,13425860,13426117,13426119,13491912,13491913,13492170,13492427,13492428,13558221,13558222,13558479,13558480,13624273,13624274,13624531,13624532,13624789,13690582,13690583,13690840,13690841,13756634,13756635,13756892,13756893,13757151,13822688,13822945,13823202,13823203,13888996,13888997,13889254,13889255,13889512,13955049,13955306,13955307,13955564,14021357,14021358,14021615,14021616,14021873,14087410,14087667,14087668,14087925,14153719
Fragment Shader code:
precision highp float;
uniform sampler2D inputImageTexture;
uniform sampler2D inputImageTexture2;
varying vec2 textureCoordinate;
uniform float uAmount;
void main() {
vec4 color = texture2D(inputImageTexture, textureCoordinate);
vec2 pos = vec2((color.r + color.g + color.b)/ 3.0, 0.0);
vec4 dstColor = texture2D(inputImageTexture2, pos);
gl_FragColor = mix(
color,
dstColor,
uAmount);
}
Help me to pass this data to sampler2D inputimageTexture2.
I am thinking that these should converted to rgb(image texture) somehow, so I can pass this to sampler2D.
I take it that the lookup table is 1 channel and 2D (16x16?). You could try uploading it with glTexImage2D as GL_FLOAT with GL_LUMINANCE or GL_ALPHA and your shader would become vec4 color = texture2D(inputImageTexture, textureCoordinate).xxxx // GL_LUMINANCE or vec4 color = texture2D(inputImageTexture, textureCoordinate).aaaa // GL_ALPHA This question is tagged as GPUImage, which I don't know at all (so what follows could be completely wrong!), but I imagine it manages its own textures so you may have to ask it to make the LUT available to your shader. Looking through the source, GPUImageRawDataInput looks like a good place to start to get your lookup table into GPUImage, maybe with something like GPUImageRawDataInput *rawInput = [[GPUImageRawDataInput alloc] initWithBytes:yourTable size:CGSizeMake(16, 16) pixelFormat:GPUPixelFormatLuminance type:GPUPixelTypeFloat];
I found solution these lookup data are 32-bit integer type. Convert 32-bit integer to RGB, then pass RGB array as texture to shader.
OpenGL ES 2.0 draw Fullscreen Quad very slow
When I'm rendering my content onto a FBO with a texture bound to it and then render this bound texture to a fullscreen quad using a basic shader the performance drops ridiculously. For example: Render to screen directly (with basic shader): And when render to texture first, then render texture with fullscreen quad: (with same basic shader, would be something like blur or bloom normally): Anyone got an idea how to speed this up? Since the current performance is not usable. Also I'm using GLKit for the basic OpenGL stuff.
Need to use precisions in places where it's needed.
lowp - for colors, textures coord, normals etc.
highp - for matrices and vertices/positions
Quick reference , check the range of precisions, on 3 page in "Qualifiers".
// BasicShader.vsh
precision mediump float;
attribute highp vec2 position;
attribute lowp vec2 texCoord;
attribute lowp vec4 color;
varying lowp vec2 textureCoord;
varying lowp vec4 textureColor;
uniform highp mat4 projectionMat;
uniform highp mat4 worldMat;
void main() {
highp mat4 worldProj = worldMat * projectionMat;
gl_Position = worldProj * vec4(position, 0.0, 1.0);
textureCoord = texCoord;
textureColor = color;
}
// BasicShader.fsh
precision mediump float;
varying lowp vec2 textureCoord;
varying lowp vec4 textureColor;
uniform sampler2D sampler;
void main() {
lowp vec4 Color = texture2D(sampler, textureCoord);
gl_FragColor = Color * textureColor;
}
This is very likely caused by ill-performant openGL ES API calls. You should attach a real device and do an openGL ES frame capture. (It really needs a real device, the option for frame capture won't be available with a simulator). The frame capture will indicate memory and other warnings along with suggestions to fix them alongside each API call. Step through these and fix each. The performance should improve considerably. Here's a couple of references to get this done: Debugging openGL ES frame Xcode tools overview
OpenGl ES on iOS lightshading removes color
I am still getting used to OpenGL with shaders, been using OGL ES 1.0 before but it's time to update my knowledge! Now I have a problem with the simple shaders I'm looking at and I have searched for 2 days straight with no luck of a solution.
Problem is this: I render some cubes with a VBO in the form of (Vx, Vy, Vz, NormalX, NormalY, NormalZ, ColorR, ColorG, ColorB, ColorA) and this works nicely when I render it without the shader but I have to use the shader for translation and stuff (I know it can be done without but bear with me). Here is my vertex shader, default from OGL template in XCode:
attribute vec4 position;
attribute vec3 normal;
uniform vec3 translation;
varying lowp vec4 colorVarying;
uniform mat4 modelViewProjectionMatrix;
uniform mat3 normalMatrix;
void main()
{
vec3 eyeNormal = normalize(normalMatrix * normal);
vec3 lightPosition = vec3(0.0, 0.0, 10.0);
vec4 diffuseColor = vec4(0.4, 0.4, 1.0, 1.0);
float nDotVP = max(0.0, dot(eyeNormal, normalize(lightPosition)));
colorVarying = diffuseColor * nDotVP;
gl_Position = modelViewProjectionMatrix * (position + vec4(translation, 1));
}
And the fragment shader, also default:
varying lowp vec4 colorVarying;
void main()
{
gl_FragColor = colorVarying;
}
Now this ALWAYS renders whatever triangles I draw in the same color (defined by diffuseColor) without regard for the colors in the VBO. So I have tried and failed with other fragment shader like gl_FragColor = gl_FrontColor; but gl_FrontColor/gl_Color etc aren't included in OpenGL ES and are deprecated in OpenGL 3.x or something. I have also viewed code using texture samplers but since I'm not using textures but colors it gets a bit complicated for a beginner.
So my question is this, how would I have my fragmentshader find the Material Color of the current fragment being shaded?
If I should pass the colors in an array to the shaders, how would I do that and how, then, would I reference it with regard to the currently shading fragment?
(Some 'also's; tried not using a fragment shader but OGL doesn't allow only using vertex shader. Tried simply removing the gl_FragColor = colorVarying; but that leaves the colors really screwed up)
You need to add a colour attribute to your shader: attribute vec4 position; attribute vec3 normal; attribute vec4 colour; ...and use that attribute instead of diffuseColor. You must also tell OpenGL where to find that vertex attribute within your VBO using glVertexAttribPointer (I assume you are doing this for the position and normal attributes already).
Shader Not Working
So i cant get my shader to render with color. My shader works when i dont set the color using the attribute Color.
my code for vertex is:
typedef struct
{
GLKVector3 Position; //Position
GLKVector4 Color; //32 Bit color
GLKVector3 Normal; //For Lighting
GLKVector2 TexCoord; //For Texturing
} Vertex;
I have given the colors for all vertices as [1,0,0,1]
My vertex shader is this:
attribute vec3 Position;
attribute vec4 Color;
attribute vec3 Normal;
attribute vec2 TexCoord;
uniform mat4 ModelViewMatrix;
uniform mat4 ProjectionMatrix;
varying vec4 DestinationColor;
void main(void)
{
gl_Position = ProjectionMatrix*ModelViewMatrix*vec4(Position,1);
DestinationColor = Color;
}
And my Fragment Shader is this:
precision mediump float;
varying lowp vec4 DestinationColor;
void main (void)
{
gl_FragColor =DestinationColor;
}
And it Displays nothing.
It doesnt even work if i change the fragment shader to say gl_FragColor = vec4(1,0,0,1); Unless i uncomment the line in vertex shader setting the DestinationColor.
Please help i have been sitting on this for a while now
I found the answer to this problem but i can't access my old account for bobjamin so I am using this new one. The solution was fairly simple. Firstly i should mention that drhass' suggestion did help in that it allowed me to set a static color from the vertex shader and it would display however the problem was that the name Color must be a reserved keyword and its was causing problems. The Answer was to change the attribute Color to SourceColor and everything worked fine!