Initial commit

resources/circle_brush.glsl

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+#version 430
+#extension GL_KHR_vulkan_glsl : enable
+
+layout(set = 0, binding = 0, rgba32f) uniform image2D texture0;
+uniform vec2 start;
+uniform vec2 stop;
+
+float distance_to_line(vec2 p1, vec2 p2, vec2 p3){
+    vec2 bvec = normalize(p2-p1);
+    vec2 avec = p3-p1;
+    float linear_projected = clamp(dot(avec, bvec), 0.0, distance(p1, p2));
+    vec2 projected = (linear_projected * bvec)+p1;
+    return length(p3-projected);
+}
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void main() {
+    ivec2 texel = ivec2(gl_GlobalInvocationID.xy);
+    float dist;
+    if(distance(start, stop)<1){
+        dist = length(texel-stop);
+    } else {
+        dist = distance_to_line(start, stop, texel);
+    }
+    if(dist<16){
+        imageStore(texture0, texel, vec4(1.0, 0.0, 0.0, 1.0));
+    }
+}

resources/render_to_screen.glsl

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+#version 430
+
+#if defined VERTEX_SHADER
+
+in vec3 in_position;
+
+void main() {
+    gl_Position = vec4(in_position, 1);
+}
+
+#elif defined FRAGMENT_SHADER
+
+uniform sampler2D texture0;
+out vec4 fragColor;
+
+void main() {
+    vec2 texel = gl_FragCoord.xy / textureSize(texture0, 0);
+    texel.y = textureSize(texture0, 0).y-texel.y;
+    fragColor = texture(texture0, texel);
+}
+
+#endif