How do I change my OpenGL texture?
To replace texture data, just bind the texture and call glTexImage2D with the new data. bindTexture, at least the opengl one, just binds a texture name to a specific target, GL_TEXTURE_2D here. It does not delete or replace anything, just put a particular texture in use.
How do I change opacity in OpenGL?
Show activity on this post. I have no idea about OpenGL ES, but in standard OpenGL you would set the opacity by declaring a colour for the texture before you use it: // R, G, B, A glColor4f(1.0, 1.0, 1.0, 0.5); The example would give you 50% alpha without affecting the colour of your texture.
Why are OpenGL textures upside down?
You probably noticed that the texture is flipped upside-down! This happens because OpenGL expects the 0.0 coordinate on the y-axis to be on the bottom side of the image, but images usually have 0.0 at the top of the y-axis.
What is glActiveTexture?
glActiveTexture selects which texture unit subsequent texture state calls will affect. The number of texture units an implementation supports is implementation dependent, but must be at least 80.
How do you use glClearColor?
To set the clear color, we use the OpenGL command glClearColor(); An example follows: glClearColor(0.0f, 0.0f, 0.0f, 0.0f); This command sets the clear color to be black. (0 red, 0 green, 0 blue, and 0 alpha).
How do I disable texture in OpenGL?
In your case, the target would be GL_TEXTURE_2D . So to answer your question: Select the texture-unit i by using glActiveTexture(GL_TEXTURE0+i) and then disable it with glDisable(GL_TEXTURE_2D) .
What is a texture unit OpenGL?
Texture units are references to texture objects that can be sampled in a shader. Textures are bound to texture units using the glBindTexture function you’ve used before. Because you didn’t explicitly specify which texture unit to use, the texture was bound to GL_TEXTURE0 .
How to update 2D textures in OpenGL?
In modern OpenGL there are 4 different methods to update 2D textures: glTexImage2D – the slowest one, recreates internal data structures. glTexSubImage2D – a bit faster, but can’t change the parameters (size, pixel format) of the image. Render-to-texture with FBO – update texture entirely on GPU, very fast.
What is OpenGL texture sampling?
Texture sampling has a loose interpretation and can be done in many different ways. It is thus our job to tell OpenGL how it should sample its textures. Texture coordinates usually range from (0,0) to (1,1) but what happens if we specify coordinates outside this range?
What is the best way to repeat a texture in OpenGL?
The default behavior of OpenGL is to repeat the texture images (we basically ignore the integer part of the floating point texture coordinate), but there are more options OpenGL offers: GL_REPEAT: The default behavior for textures. Repeats the texture image. GL_MIRRORED_REPEAT: Same as GL_REPEAT but mirrors the image with each repeat.
Why is my texture upside down in OpenGL?
You should get the following result: You probably noticed that the texture is flipped upside-down! This happens because OpenGL expects the 0.0 coordinate on the y-axis to be on the bottom side of the image, but images usually have 0.0 at the top of the y-axis.