75 lines
2.4 KiB
GLSL
75 lines
2.4 KiB
GLSL
shader_type canvas_item;
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render_mode unshaded;
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uniform vec2 viewport_size; // size in pixels of the viewport. Cannot be access from the shader in GLES2
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uniform sampler2D viewport1 : hint_albedo;
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uniform sampler2D viewport2 : hint_albedo;
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uniform bool split_active; // true: split screen, false: use view1
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uniform vec2 player1_position; // position of player 1 un UV coordinates
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uniform vec2 player2_position; // position of player 2 un UV coordinates
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uniform float split_line_thickness; // width of the split boder
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uniform vec4 split_line_color; // color of the split border
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// from https://stackoverflow.com/questions/15276454/is-it-possible-to-draw-line-thickness-in-a-fragment-shader
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float distanceToLine(vec2 p1, vec2 p2, vec2 point) {
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float a = p1.y - p2.y;
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float b = p2.x - p1.x;
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return abs(a * point.x + b * point.y + p1.x * p2.y - p2.x * p1.y) / sqrt(a * a + b * b);
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}
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void fragment() {
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vec3 view1 = texture(viewport1, UV).rgb;
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vec3 view2 = texture(viewport2, UV).rgb;
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float width = viewport_size.x;
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float height = viewport_size.y;
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if (split_active) {
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vec2 dx = player2_position - player1_position;
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float split_slope;
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if (dx.y != 0.0) {
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split_slope = dx.x / dx.y;
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}
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else {
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split_slope = 100000.0; // High value (vertical split) if dx.y = 0
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}
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vec2 split_origin = vec2(0.5, 0.5);
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vec2 split_line_start = vec2(0.0, height * ((split_origin.x - 0.0) * split_slope + split_origin.y));
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vec2 split_line_end = vec2(width, height * ((split_origin.x - 1.0) * split_slope + split_origin.y));
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float distance_to_split_line = distanceToLine(split_line_start, split_line_end, vec2(UV.x * width, UV.y * height));
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// Draw split border if close enough
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if (distance_to_split_line < split_line_thickness) {
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COLOR = split_line_color;
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}
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else {
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float split_current_y = (split_origin.x - UV.x) * split_slope + split_origin.y;
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float split_player1_position_y = (split_origin.x - player1_position.x) * split_slope + split_origin.y;
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// Check on which side of the split UV is and select the proper view
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if (UV.y > split_current_y) {
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if (player1_position.y > split_player1_position_y) {
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COLOR = vec4(view1, 1.0);
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}
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else {
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COLOR = vec4(view2, 1.0);
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}
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}
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else {
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if (player1_position.y < split_player1_position_y) {
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COLOR = vec4(view1, 1.0);
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}
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else {
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COLOR = vec4(view2, 1.0);
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}
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}
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}
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}
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else {
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COLOR = vec4(view1, 1.0);
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}
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}
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