Add threshold geometry shader, refactor vertex and fragment shaders

scwx-qt/gl/color.frag

@@ -1,5 +1,5 @@
 #version 330 core
-in vec4 color;
+smooth in vec4 color;
 
 layout (location = 0) out vec4 fragColor;
 

scwx-qt/gl/color.vert

@@ -4,7 +4,7 @@ layout (location = 1) in vec4 aColor;
 
 uniform mat4 uMVPMatrix;
 
-out vec4 color;
+smooth out vec4 color;
 
 void main()
 {

scwx-qt/gl/geo_line.vert

@@ -16,7 +16,7 @@ uniform mat4 uMapMatrix;
 uniform vec2 uMapScreenCoord;
 
 smooth out vec2 texCoord;
-flat   out vec4 modulate;
+smooth out vec4 color;
 
 vec2 latLngToScreenCoordinate(in vec2 latLng)
 {
@@ -31,7 +31,7 @@ void main()
 {
    // Pass the texture coordinate and color modulate to the fragment shader
    texCoord = aTexCoord;
-   modulate = aModulate;
+   color    = aModulate;
 
    vec2 p = latLngToScreenCoordinate(aLatLong) - uMapScreenCoord;
 

scwx-qt/gl/geo_texture2d.vert

@@ -12,13 +12,21 @@ layout (location = 1) in vec2  aXYOffset;
 layout (location = 2) in vec2  aTexCoord;
 layout (location = 3) in vec4  aModulate;
 layout (location = 4) in float aAngleDeg;
+layout (location = 5) in int   aThreshold;
 
 uniform mat4 uMVPMatrix;
 uniform mat4 uMapMatrix;
 uniform vec2 uMapScreenCoord;
 
+out VertexData
+{
+   int  threshold;
+   vec2 texCoord;
+   vec4 color;
+} vsOut;
+
 smooth out vec2 texCoord;
-flat   out vec4 modulate;
+smooth out vec4 color;
 
 vec2 latLngToScreenCoordinate(in vec2 latLng)
 {
@@ -31,9 +39,15 @@ vec2 latLngToScreenCoordinate(in vec2 latLng)
 
 void main()
 {
-   // Pass the texture coordinate and color modulate to the fragment shader
-   texCoord = aTexCoord;
-   modulate = aModulate;
+   // Pass the threshold to the geometry shader
+   vsOut.threshold = aThreshold;
+
+   // Pass the texture coordinate and color modulate to the geometry and
+   // fragment shaders
+   vsOut.texCoord = aTexCoord;
+   vsOut.color    = aModulate;
+   texCoord       = aTexCoord;
+   color          = aModulate;
 
    vec2 p = latLngToScreenCoordinate(aLatLong) - uMapScreenCoord;
 

scwx-qt/gl/map_color.vert

@@ -3,17 +3,29 @@
 layout (location = 0) in vec2 aScreenCoord;
 layout (location = 1) in vec2 aXYOffset;
 layout (location = 2) in vec4 aColor;
+layout (location = 3) in int  aThreshold;
 
 uniform mat4 uMVPMatrix;
 uniform mat4 uMapMatrix;
 uniform vec2 uMapScreenCoord;
 
-out vec4 color;
+out VertexData
+{
+   int  threshold;
+   vec2 texCoord;
+   vec4 color;
+} vsOut;
+
+smooth out vec4 color;
 
 void main()
 {
-   // Pass the color to the fragment shader
-   color = aColor;
+   // Pass the threshold and color to the geometry shader
+   vsOut.threshold = aThreshold;
+
+   // Pass the color to the geometry and fragment shaders
+   vsOut.color = aColor;
+   color       = aColor;
 
    vec2 p = aScreenCoord - uMapScreenCoord;
 

scwx-qt/gl/texture2d.frag

@@ -6,11 +6,11 @@ precision mediump float;
 uniform sampler2D uTexture;
 
 smooth in vec2 texCoord;
-flat   in vec4 modulate;
+smooth in vec4 color;
 
 layout (location = 0) out vec4 fragColor;
 
 void main()
 {
-   fragColor = texture(uTexture, texCoord) * modulate;
+   fragColor = texture(uTexture, texCoord) * color;
 }

scwx-qt/gl/threshold.geom

@@ -0,0 +1,41 @@
+#version 330 core
+
+layout (triangles) in;
+layout (triangle_strip, max_vertices = 3) out;
+
+uniform float uMapDistance;
+
+in VertexData
+{
+   int  threshold;
+   vec2 texCoord;
+   vec4 color;
+} gsIn[];
+
+smooth out vec2 texCoord;
+smooth out vec4 color;
+
+void main()
+{
+   if (gsIn[0].threshold <= 0 ||            // If Threshold: 0 was specified, no threshold
+       gsIn[0].threshold >= uMapDistance || // If Threshold is above current map distance
+       gsIn[0].threshold >= 999)            // If Threshold: 999 was specified (or greater), no threshold
+   {
+      gl_Position = gl_in[0].gl_Position;
+      texCoord    = gsIn[0].texCoord;
+      color       = gsIn[0].color;
+      EmitVertex();
+
+      gl_Position = gl_in[1].gl_Position;
+      texCoord    = gsIn[1].texCoord;
+      color       = gsIn[1].color;
+
+      EmitVertex();
+      gl_Position = gl_in[2].gl_Position;
+      texCoord    = gsIn[2].texCoord;
+      color       = gsIn[2].color;
+
+      EmitVertex();
+      EndPrimitive();
+   }
+}

scwx-qt/scwx-qt.cmake

@@ -252,7 +252,8 @@ set(SHADER_FILES gl/color.frag
                  gl/text.vert
                  gl/texture1d.frag
                  gl/texture1d.vert
-                 gl/texture2d.frag)
+                 gl/texture2d.frag
+                 gl/threshold.geom)
 
 set(CMAKE_FILES scwx-qt.cmake)
 

scwx-qt/scwx-qt.qrc

@@ -12,6 +12,7 @@
         <file>gl/texture1d.frag</file>
         <file>gl/texture1d.vert</file>
         <file>gl/texture2d.frag</file>
+        <file>gl/threshold.geom</file>
         <file>res/config/radar_sites.json</file>
         <file>res/fonts/din1451alt.ttf</file>
         <file>res/fonts/din1451alt_g.ttf</file>