using this code I can send one texture to the shader:
devcon->PSSetShaderResources(0, 1, &pTexture);
Of course i made the pTexture by: D3DX11CreateShaderResourceViewFromFile
Shader:
Texture2D Texture;
return color * Texture.Sample(ss, texcoord);
I'm currently only sending one texture to the shader, but I would like to send multiple textures, how is this possible?
Thank You.
You can use multiple textures as long as their count does not exceed your shader profile specs. Here is an example:
HLSL Code:
Texture2D diffuseTexture : register(t0);
Texture2D anotherTexture : register(t1);
C++ Code:
devcon->V[P|D|G|C|H]SSetShaderResources(texture_index, 1, &texture);
So for example for above HLSL code it will be:
devcon->PSSetShaderResources(0, 1, &diffuseTextureSRV);
devcon->PSSetShaderResources(1, 1, &anotherTextureSRV); (SRV stands for Shader Texture View)
OR:
ID3D11ShaderResourceView * textures[] = { diffuseTextureSRV, anotherTextureSRV};
devcon->PSSetShaderResources(0, 2, &textures);
HLSL names can be arbitrary and doesn't have to correspond to any specific name - only indexes matter. While "register(tXX);" statements are not required, I'd recommend you to use them to avoid confusion as to which texture corresponds to which slot.
By using Texture Arrays. When you fill out your D3D11_TEXTURE2D_DESC look at the ArraySize member. This desc struct is the one that gets passed to ID3D11Device::CreateTexture2D. Then in your shader you use a 3rd texcoord sampling index which indicates which 2D texture in the array you are referring to.
Update: I just realised you might be talking about doing it over multiple calls (i.e. for different geo), in which case you update the shader's texture resource view. If you are using the effects framework you can use ID3DX11EffectShaderResourceVariable::SetResource, or alternatively rebind a new texture using PSSetShaderResources. However, if you are trying to blend between multiple textures, then you should use texture arrays.
You may also want to look into 3D textures, which provide a natural way to interpolate between adjacent textures in the array (whereas 2D arrays are automatically clamped to the nearest integer) via the 3rd element in the texcoord. See the HLSL sample remarks.
Related
I'm developing a 3d program with OpenGL 3.3. So far I managed to render many cubes and some spheres. I need to texture all the faces of all the cubes with a common texture except one face which should have a different texture. I tried with a single texture and everything worked fine but when I try to add another one the program seems to behave randomly.
My questions:
is there a suitable way of passing multiple textures to the shaders?
how am I supposed to keep track of faces in order to render the right texture?
Googling I found out that it could be useful to define vertices twice, but I don't really get why.
Is there a suitable way of passing multiple textures to the shaders?
You'd use glUniform1i() along with glActiveTexture(). Thus given your fragment shader has multiple uniform sampler2D:
uniform sampler2D tex1;
uniform sampler2D tex2;
Then as you're setting up your shader, you set the sampler uniforms to the texture units you want them associated with:
glUniform1i(glGetUniformLocation(program, "tex1"), 0)
glUniform1i(glGetUniformLocation(program, "tex2"), 1)
You then set the active texture to either GL_TEXTURE0 or GL_TEXTURE1 and bind a texture.
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D, texture1)
glActiveTexture(GL_TEXTURE1)
glBindTexture(GL_TEXTURE_2D, texture2)
How am I supposed to keep track of faces in order to render the right texture?
It depends on what you want.
You could decide which texture to use based the normal (usually done with tri-planar texture mapping).
You could also have another attribute that decides how much to crossfade between the two textures.
color = mix(texture(tex1, texCoord), texture(tex2, texCoord), 0.2)
Like before, you can equally have a uniform float transition. This would allow you to fade between textures, making it possible to fade between slides like in PowerPoint, so to speak.
Try reading LearnOpenGL's Textures tutorial.
Lastly there's a minimum of 80 texture units. You can check specifically how many you have available using GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS.
You can use index buffers. Define the vertices once, and then use one index buffer to draw the portion of the mesh with the first texture, then use the second index buffer to draw the portion that needs the second texture.
Here's the general formula:
Setup the vertex buffer
Setup the shader
Setup the first texture
Setup and draw the index buffer for the part of the mesh that should use the first texture
Setup the second texture
Setup and draw the index buffer for the part of the mesh that should use the second texture.
I'd like to access framebuffer to get RGB and change their values for each pixel. It is because the glReadPixels, and glDrawPixels are too slow to use, so that i should use shaders instead of using them.
Now, I write code, and success to display three-dimensional model using GLSL shaders.
I drew two cubes as follows.
....
glDrawArrays(GL_TRIANGLES, 0, 12*6);
....
and fragment shader :
varying vec3 fragmentColor;
void main()
{
gl_FragColor = vec4(fragmentColor, 1);
}
Then, how can I access to RGB values and change it?
For example, If the pixel values at (u1, v1) on window and (u2, v2) are (0,0,255), then I want to change them to (255,0,0)
With the exception of an OpenGL ES-only extension, fragment shaders cannot just read from the current framebuffer. Otherwise, we wouldn't need blending.
You also can't just render to the image you're reading from in a shader. So if you need to do some sort of post-processing, then that is best done by rendering to a separate image. That is, you do your rendering to image 1, then bind that as a texture and change the FBO so that you're rendering to image 2.
Alternatively, if you have access to OpenGL 4.5/ARB/NV_texture_barrier, then you can use texture barriers to handle this. This permits you a single read/modify/write pass, if you bind the current framebuffer's image as a texture. You'd issue the barrier before doing your read/modify/write, then bind that texture to a sampler while still rendering to that framebuffer.
Also, this requires that the FS read from the exact texel that it would write to. Assuming a viewport anchored at 0,0, the code for this would be texelFetch(sampler, ivec2(gl_FragCoord.xy), 0). You can't read from someone else's texel and modify it.
Obviously you must be rendering to a texture; you cannot use the default framebuffer for this.
Texture barrier could be used for cases where you read from different texels than you write to. But that would require doing something similar to the first case of switching bound images. Though you wouldn't need to change the FBO exactly; you could change the region of the FBO that you render to. That is, so long as you're reading from a different area than you're rendering to, and you use barriers appropriately when switching between those regions, everything is fine.
I need to pass a 2D (Rectangle) texture to my fragment shader. The data in the texture must be read in the sampler as a uniform. Depending on the value read in the texture, the color of a pixel will or will not be changed.
here is my code in the API to bind texture and sampler:
//create texture and sampler
glEnable(GL_TEXTURE_2D);
GLuint CosineTexture;
glGenTextures(1,&CosineTexture);
glTexStorage2D(GL_TEXTURE_RECTANGLE,1,GL_RGBA,1440,1080);
glTexSubImage2D(GL_TEXTURE_RECTANGLE,0,0,0,1440,1080,GL_RGBA,GL_FLOAT,dataCosines1);
GLuint SensorCosines;
glGenSamplers(1,&SensorCosines);
glActiveTexture(GL_TEXTURE0 + 0);
glBindTexture(GL_TEXTURE_RECTANGLE,CosineTexture);
glBindSampler(0,SensorCosines);
and here is my code in the shader to receive and read from the texture:
uniform samplerRect SensorCosines;
...
float textureValue;
textureValue = texture(SensorCosines, Bin).r;
Nothing happens. So, I guess that my texture is not being passed to the shader. My feeling is that it is at the level of binding texture to sampler in the API but I have no clue what is my error.
glTexStorage2D(GL_TEXTURE_RECTANGLE,1,GL_RGBA,1440,1080);
This call will produce an OpenGL error. Specifically, GL_INVALID_ENUM. You must use sized image formats when using glTexStorage functions. GL_RGBA is not a sized image format.
You may have other problems in un-shown code, but this is certainly one of the issues.
I have few textures that I want to set in my HLSL shader as array.
Each texture is represented as ID3D11ShaderResourceView*.
Each texture may be DIFFERENT size.
Now, If I set them in D3D as array:
ID3D11ShaderResourceView* m_array[3];
m_array[0] = ...;
m_array[1] = ...;
m_array[2] = ...;
m_deviceContext->PSSetShaderResources(
0, // Start slot
3, // Nb of textures
m_array); // Array
And in my HLSL shader I declared:
Texture2D g_textures[3];
Will it be mapped correctly?
This is in general a method you can use to map texture arrays from runtime to shader execution. It does not matter that the texture dimensions in the array match, however, you may need to account for this within your shader code, depending on exactly how you are sampling the textures.
Also, in your HLSL, you making the assumption that the g_textures array is assigned to slot 0, so if for some reason it doesn't actually go there (eg. there is another texture resource that comes before it in the shader source), then you won't be setting the intended resource to the correct slot. I find it's better to map them explicitly, eg:
Texture2D g_textures[3] : register(t0);
If there is a collision, it will be found at (shader) compile time.
I have a functioning OpenGL ES 3 program (iOS), but I've having a difficult time understanding OpenGL textures. I'm trying to render several quads to the screen, all with different textures. The textures are all 256 color images with a sperate palette.
This is C++ code that sends the textures to the shaders
// THIS CODE WORKS, BUT I'M NOT SURE WHY
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, _renderQueue[idx]->TextureId);
glUniform1i(_glShaderTexture, 1); // what does the 1 mean here
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, _renderQueue[idx]->PaletteId);
glUniform1i(_glShaderPalette, 2); // what does the 2 mean here?
glDrawElements(GL_TRIANGLES, sizeof(Indices)/sizeof(Indices[0]), GL_UNSIGNED_BYTE, 0);
This is the fragment shader
uniform sampler2D texture; // New
uniform sampler2D palette; // A palette of 256 colors
varying highp vec2 texCoordOut;
void main()
{
highp vec4 palIndex = texture2D(texture, texCoordOut);
gl_FragColor = texture2D(palette, palIndex.xy);
}
As I said, the code works, but I'm unsure WHY it works. Several seemingly minor changes break it. For example, using GL_TEXTURE0, and GL_TEXTURE1 in the C++ code breaks it. Changing the numbers in glUniform1i to 0, and 1 break it. I'm guessing I do not understand something about texturing in OpenGL 3+ (maybe Texture Units???), but need some guidance to figure out what.
Since it's often confusing to newer OpenGL programmers, I'll try to explain the concept of texture units on a very basic level. It's not a complex concept once you pick up on the terminology.
The whole thing is motivated by offering the possibility of sampling multiple textures in shaders. Since OpenGL traditionally operates on objects that are bound with glBind*() calls, this means that an option to bind multiple textures is needed. Therefore, the concept of having one bound texture was extended to having a table of bound textures. What OpenGL calls a texture unit is an entry in this table, designated by an index.
If you wanted to describe this state in a C/C++ style notation, you could define the table of bound texture as an array of texture ids, where the size is the maximum number of bound textures supported by the implementation (queried with glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS, ...)):
GLuint BoundTextureIds[MAX_TEXTURE_UNITS];
If you bind a texture, it gets bound to the currently active texture unit. This means that the last call to glActiveTexture() determines which entry in the table of bound textures is modified. In a typical call sequence, which binds a texture to texture unit i:
glActiveTexture(GL_TEXTUREi);
glBindTexture(GL_TEXTURE_2D, texId);
this would correspond to modifying our imaginary data structure by:
BoundTextureIds[i] = texId;
That covers the setup. Now, the shaders can access all the textures in this table. Variables of type sampler2D are used to access textures in the GLSL code. To determine which texture each sampler2D variable accesses, we need to specify which table entry each one uses. This is done by setting the uniform value to the table index:
glUniform1i(samplerLoc, i);
specifies that the sampler uniform at location samplerLoc reads from table entry i, meaning that it samples the texture with id BoundTextureIds[i].
In the specific case of the question, the first texture was bound to texture unit 1 because glActiveTexture(GL_TEXTURE1) was called before glBindTexture(). To access this texture from the shader, the shader uniform needs to be set to 1 as well. Same thing for the second texture, with texture unit 2.
(The description above was slightly simplified because it did not take into account different texture targets. In reality, textures with different targets, e.g. GL_TEXTURE_2D and GL_TEXTURE_3D, can be bound to the same texture unit.)
GL_TEXTURE1 and GL_TEXTURE2 refer to texture units. glUniform1i takes a texture unit id for the second argument for samplers. This is why they are 1 and 2.
From the OpenGL website:
The value of a sampler uniform in a program is not a texture object,
but a texture image unit index. So you set the texture unit index for
each sampler in a program.