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Asked By
HeroicNate
I am trying to make a shader to warp an image in godot, but I only seem to create uniform skews and all tutorials just show me how to make things wiggle. How can I make the can accomplish what I have in the image below?
shader_type canvas_item;
// naming in UV system _x_y
uniform vec2 offset_0_0 = vec2(0.0, 0.0);
uniform vec2 offset_0_1 = vec2(0.0, 0.0);
uniform vec2 offset_1_0 = vec2(0.0, 0.0);
uniform vec2 offset_1_1 = vec2(0.0, 0.0);
vec2 sample_point(vec2 point) {
// Corners for UV.y == 0
vec2 p_0_0 = vec2(0,0) - offset_0_0;
vec2 p_1_0 = vec2(1,0) - offset_1_0;
// Get point along line UV.y == 0
vec2 d_x_0 = p_0_0 + (p_1_0 - p_0_0) * point.x;
// Corners for UV.y == 1.0
vec2 p_0_1 = vec2(0, 1) - offset_0_1;
vec2 p_1_1 = vec2(1, 1) - offset_1_1;
// Get point along line UV.y == 1
vec2 d_x_1 = p_0_1 + (p_1_1 - p_0_1) * point.x;
// Get point for given UV.y
return d_x_0 + (d_x_1 - d_x_0) * point.y;
}
void fragment() {
//COLOR = vec4(UV.x, UV.y, .0, 1.0);
//COLOR = texture(TEXTURE, UV);
//COLOR = texture(TEXTURE, sample_point(UV));
}
void vertex() {
VERTEX += sample_point(UV);
}
I’ve kept the fragment code as we can distort using fragment() only. This requires to comment out the vertex call and scale offsets in range [0,1]
Using a sprite does not work as that has 2 triangles for its quad so there is big distortion. For that to work I guess sample_point must be split into _fragment and _vertex variant.
