.

Engine/assets/shader/mesh.shader

@@ -11,7 +11,7 @@ layout (location = 3) in int aTextureId;
 layout (location = 4) in mat4 aModelMatrix;
 
 layout (location = 0) out vec2 oUV;
-layout (location = 1) out int oTextureId;
+layout (location = 1) flat out int oTextureId;
 layout (location = 2) out vec3 oNormal;
 
 void main()
@@ -35,7 +35,7 @@ layout (location = 0) out vec4 FragColor;
 
 void main()
 {
-    vec3 lightColor = vec3(iUV, 0);
+    vec3 lightColor = vec3(1);
     FragColor = vec4(lightColor, 1.0);
     if (iTextureId >= 0)
         FragColor *= texture(uTexture[iTextureId], iUV);

Engine/assets/shader/quad.shader

@@ -12,7 +12,7 @@ layout (location = 4) in mat4 aModel;
 
 layout (location = 0) out vec4 oColor;
 layout (location = 1) out vec2 oUV;
-layout (location = 2) out int oTextureId;
+layout (location = 2) flat out int oTextureId;
 
 void main()
 {

Engine/assets/shader/text.shader

@@ -0,0 +1,61 @@
+// #type vertex
+#version 460 core
+
+uniform mat4 u_Projection;
+uniform mat4 u_View;
+
+layout (location = 0) in vec4 a_Position;
+layout (location = 1) in vec2 a_UV;
+layout (location = 2) in vec4 a_Color;
+layout (location = 3) in int a_AtlasId;
+layout (location = 4) in vec2 a_UnitRange;
+layout (location = 5) in mat4 a_Model;
+
+layout (location = 0) out vec4 o_Color;
+layout (location = 1) out vec2 o_UV;
+layout (location = 2) flat out int o_AtlasId;
+layout (location = 3) flat out vec2 o_UnitRange;
+
+void main()
+{
+    o_Color = a_Color;
+    o_UV = a_UV;
+    o_AtlasId = a_AtlasId;
+    o_UnitRange = a_UnitRange;
+
+    gl_Position = u_Projection * u_View * a_Model * a_Position;
+}
+
+// #type fragment
+#version 460 core
+
+uniform sampler2D u_Atlas[16];
+
+layout (location = 0) in vec4 i_Color;
+layout (location = 1) in vec2 i_UV;
+layout (location = 2) flat in int i_AtlasId;
+layout (location = 3) flat in vec2 i_UnitRange;
+
+layout (location = 0) out vec4 FragColor;
+
+float median(float r, float g, float b) {
+    return max(min(r, g), min(max(r, g), b));
+}
+
+float screenPxRange() {
+    vec2 screenTexSize = vec2(1.0) / fwidth(i_UV);
+    return max(0.5 * dot(i_UnitRange, screenTexSize), 1.0);
+}
+
+void main()
+{
+    vec3 msd = texture(u_Atlas[i_AtlasId], i_UV).rgb;
+    float sd = median(msd.r, msd.g, msd.b);
+    float screenPxDistance = screenPxRange() * (sd - 0.5);
+    float opacity = clamp(screenPxDistance + 0.5, 0.0, 1.0);
+    // this is a temporary solution for TODO: fix depth test self discard on overlap
+    if (opacity == 0.0) {
+        discard;
+    }
+    FragColor = mix(vec4(0), i_Color, opacity);
+}