is there a equivalent to unity lerp function in Godot shader. I have tried Mix function it does not work. I have attached the screenshot of what is required. Any help is appreciated. Thanks in advance
create a gradient texture that does not change vertically when object is moved
I cannot mix 2 colours in Godot like as show in the unity screenshot.
like the shader where you have both blue and red separate based on some weightage
sstelkar You can. See the reply above.
For anyone else struggling with Shader Graph nodes from Unity possibly still missing in Godot: you can replicate them on your own very easily. Shader Graph is well documented, so you don't even have to look through the sources yourself.
For example:
ShaderGraph "Blend Node", the "Overwrite" mode. Source from documentation:
void Unity_Blend_Overwrite_float4(float4 Base, float4 Blend, float Opacity, out float4 Out) {
Out = lerp(Base, Blend, Opacity);
}
Converted to Godot:
void Godot_Blend_Overwrite_vec4(vec4 Base, vec4 Blend, float Opacity, out vec4 Out){
Out = mix(Base, Blend, Opacity);
}
As you can see, "mix" is the Godot equivalent to "lerp" from Unity, and "float4" becomes "vec4". It's all simple and documented, you just have to learn how and what to look/search for.
- Edited
I'm building a bottle fill game. all the logic is working. I'm able to work without shader above image is without using shaders. I'm trying to use shader for the animation part to make it nicer running into trouble
Plain "uv" is in object-space.
sstelkar changed the title to create a gradient texture that does not change vertically when object is moved .
- Edited
- Best Answerset by sstelkar
sstelkar You could probably do it by fudging screen UVs but it's better to use object's UV for multiple reasons, one being a nice zoom independent preview in editor and the other is that tilting the bottle may hide considerable parts of the screen space gradient at the top/bottom. Instead, better to transform local uv space to stretch between top and bottom of bottle's rotated bounding box.
Easiest way is to construct a shear matrix that shears the uv space around uv center (.5,.5) for a certain angle, to compensate for the tilt caused by rotation. Calculating this angle is the trickiest part, but here's the recipe:
float scaleRatio = length(MODEL_MATRIX[0]) / length(MODEL_MATRIX[1]);
float imageRatio = TEXTURE_PIXEL_SIZE.y / TEXTURE_PIXEL_SIZE.x;
float shearAngle = atan(MODEL_MATRIX[0].y * scaleRatio * imageRatio, MODEL_MATRIX[0].x );If you don't have non-proportional scaling on the bottle sprite, simply remove scaleRatio from calculation.
Once you have the angle, construct the shearMatrix with following basis vectors:
shearMatrix = mat4(
vec4(1.0, sin(shearAngle), 0.0, 0.0),
vec4(0.0, cos(shearAngle), 0.0, 0.0),
vec4(0.0, 0.0, 1.0, 0.0),
vec4(0.0, 0.5, 0.0, 0.0)
);The above should be done in vertex function and the shearMatrix passed to fragment function as a varying.
In fragment shader, subtract the object space UV from (.5,.5) to bring it to center and then multiply it with the shearMatrix. Use resulting V to drive your gradients.
