feat: default projection mapping with shift + M

default/forge_project.cfg

@@ -235,10 +235,11 @@ GROUP_1_6_Y=19
 GROUP_1_6_Z=
 
 # Same for group 2
-GROUP_2_ACTIVE_COUNT=3
+GROUP_2_ACTIVE_COUNT=4
 GROUP_2_ACTIVE_1=36
 GROUP_2_ACTIVE_2=68
 GROUP_2_ACTIVE_3=52
+GROUP_2_ACTIVE_4=11077
 GROUP_2_COUNT=7
 GROUP_2_1_X=37
 GROUP_2_1_Y=53

default/frag9.glsl

@@ -6,8 +6,40 @@
 in vec2 vUV;
 out vec4 fragColor;
 
+#include inc_map.glsl
+
 uniform sampler2D iTex0;
+uniform int iAutoRand;
+uniform vec3 iGroup2_4[7];
 
 void main() {
-    fragColor = texture(iTex0, vUV);
+    bool visible = iAutoRand < 1 && iGroup2_4[0].x > 0;
+    bool invert = iAutoRand < 1 && iGroup2_4[0].y > 0;
+    bool rect = iAutoRand < 1 && iGroup2_4[0].z > 0;
+
+    vec2 uv2 = vUV;
+
+    if (visible) {
+        vec2 p1 = iAutoRand < 1 ? vec2(iGroup2_4[6].xy) : vec2(0);
+        vec2 p2 = iAutoRand < 1 ? vec2(iGroup2_4[1].xy) : vec2(0);
+        vec2 p3 = iAutoRand < 1 ? vec2(iGroup2_4[3].xy) : vec2(0);
+        vec2 p4 = iAutoRand < 1 ? vec2(iGroup2_4[5].xy) : vec2(0);
+
+        p2.x = 1 - p2.x;
+        p3.y = 1 - p3.y;
+        p4.x = 1 - p4.x;
+        p4.y = 1 - p4.y;
+
+        uv2 = project_4p(vUV, p1, p2, p3, p4);
+    }
+
+    vec4 color = texture(iTex0, invert ? vUV : uv2);
+
+    if (visible) {
+        float mask = step(0, uv2.x) * step(-1, -uv2.x) * step(0, uv2.y) * step(-1, -uv2.y);
+        color *= mix(mask, 1 - mask, invert ? 1 : 0);
+        color = mix(color, mix(color, color + mask * vec4(1), step(uv2.x, 0.01) + step(uv2.y, 0.01) + step(1 - uv2.y, 0.01) + step(1 - uv2.x, 0.01)), rect ? 1 : 0);
+    }
+
+    fragColor = color;
 }

default/inc_map.glsl

@@ -0,0 +1,26 @@
+#ifndef INC_MAP
+#define INC_MAP
+
+vec2 project_4p(vec2 uv, vec2 p1, vec2 p2, vec2 p3, vec2 p4) {
+    float k1 = (p4.y - p3.y) / (p2.y - p3.y);
+    float k2 = (p3.y - p1.y) / (p2.y - p3.y);
+    float a = (p4.x - p3.x + k1 * p3.x - k1 * p2.x) / (p1.x - p3.x - k2 * p3.x + k2 * p2.x);
+    float b = k1 + a * k2;
+    float c = 1 - a - b;
+    // https://math.stackexchange.com/questions/296794/finding-the-transform-matrix-from-4-projected-points-with-javascript/339033#339033
+    mat3 projection_a = mat3(
+            a * p1.x, a * p1.y, a,
+            b * p2.x, b * p2.y, b,
+            c * p3.x, c * p3.y, c
+        );
+    mat3 projection_a_prime = inverse(projection_a);
+    mat3 projection_b = mat3(
+            0, 0, -1,
+            1, 0, 1,
+            0, 1, 1
+        );
+    vec3 tmp = projection_b * projection_a_prime * vec3(uv, 1);
+    return tmp.xy / tmp.z;
+}
+
+#endif