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Asked: 2025-04-23T02:14:02+05:30

How can I achieve the water wave effect using the R and G channels of the provided texture?

I’ve been diving deep into creating a water wave effect using a fragment shader, and I hit a wall. I’ve been trying to replicate an effect I stumbled upon in a blog post. The author does an amazing job demonstrating how they achieved this wavy water look with just one texture read, and I’m so intrigued by the underlying technique.

In the post, the author shows this pretty cool video of animated waves, which just pulls me in every time I watch it. The texture they used holds all the secrets, or at least that’s what I’m hoping for. They mention that the R and G channels of this texture encode something crucial for the wave effect, while the B and A channels serve as masks. After isolating the R and G channels, I can see they have some interesting patterns, but I’m at a complete standstill trying to figure out how to utilize them to create those animated waves.

I’ve attempted a bunch of different strategies, including comparing the R and G channels to varying thresholds, hoping to latch onto something that resembles the movement of waves. I also tried calculating the dot product between the camera view direction and the X,Y values from these channels, but honestly, it hasn’t given me anything even close to what I’m looking for.

I even reached out to the author, but they mentioned they randomly experimented until things just clicked for them, which is both inspiring and frustrating! I could really use some insight from anyone who’s attempted something similar. Is there a technique to combine or manipulate these channels that I might be overlooking? Maybe a specific mathematical operation or creative approach that would allow me to harness the texture effectively? I’m open to any advice, ideas, or even pointers that could help spark some inspiration. I really want to make those waves come to life!

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    2 Answers

    1. Trying to Create Wave Effects with Shader

      It sounds like you’re really diving deep into creating a cool water wave effect! That kind of shader work can be quite tricky, especially with just a single texture read. The way the R and G channels are used for wave patterns is definitely a neat trick!

      If you’re stuck on how to utilize those R and G channels, here are a few ideas that might help:

      • Combine R and G Channels: Try using a mix of both R and G values to create a new value that can represent the height or intensity of the waves. You could use something like vec2 wave = vec2(texture.r, texture.g); and then manipulate this value based on time or camera position!
      • Sinusoidal Functions: Use sine or cosine functions to animate the waves. For example, you could do something like float waveHeight = sin(u_time + wave.x * frequency) * amplitude; to get a nice oscillation.
      • Thresholding: Since you’ve tried thresholds already, maybe experiment with different ranges to isolate specific wave patterns. Sometimes, adjusting your thresholds a bit can yield different results!
      • Directional Influence: You mentioned trying the dot product; maybe try to visualize it differently. It could help to visualize how waves would respond to movement by translating your patterns along the direction of the waves.
      • Layering Effects: Try layering multiple wave patterns on top of each other with varying frequencies and amplitudes. This could create a more complex and lifelike appearance.

      Shaders can often need a lot of experimenting. Maybe picking a simple setup and gradually adding complexity can help clear some of that confusion. Sometimes, you need to play around with values until something clicks, just like the author mentioned!

      Keep at it, and don’t get discouraged! It’s all part of the learning process. Who knows, you might stumble onto your own unique approach to those waves!

    2. The R and G channels you mentioned are likely encoding directional displacement vectors for each pixel—commonly known as normal maps or flow maps. By treating them as signed offsets instead of thresholds, you enable smooth directional movement that mimics wave dynamics. Specifically, remap the R and G values from the [0,1] range to [-1,1] to obtain offset directions, then apply these as UV shifts when sampling your water texture over time. A common approach is to introduce a dynamic factor such as time multiplied by a speed scalar, allowing continuous scrolling of texture coordinates using these directional offsets and creating an animated wave effect with just one texture lookup.

      Additionally, combining these offset UVs with techniques like sine or cosine modulation of time can greatly enhance realism by introducing cyclic motion patterns. Try applying a small-scale sine wave animation to the offset vectors themselves, allowing gradual transitions and more pronounced wave crests and troughs. Experimenting with multiplication factors for offset amplitude and animation period can often yield visually richer results. Also, ensure your final calculated UVs include wrapping (repeat mode) to handle boundaries seamlessly. These subtle mathematical manipulations can unlock the simple yet visually appealing water animations you’re aiming for.