Merge pull request #3634 from benpm/issue/3596-saturn-ring-shadow

Issue/3596 saturn ring shadow. fixes #3596

modules/globebrowsing/shaders/advanced_rings_fs.glsl

@@ -31,6 +31,7 @@
 in vec2 vs_st;
 in float vs_screenSpaceDepth;
 in vec4 shadowCoords;
+in vec3 vs_normal;
 
 uniform sampler2DShadow shadowMapTexture;
 uniform sampler1D ringTextureFwrd;

modules/globebrowsing/shaders/advanced_rings_vs.glsl

@@ -28,10 +28,12 @@
 
 layout(location = 0) in vec2 in_position;
 layout(location = 1) in vec2 in_st;
+layout(location = 2) in vec3 in_normal;
 
 out vec2 vs_st;
 out float vs_screenSpaceDepth;
 out vec4 shadowCoords;
+out vec3 vs_normal;
 
 uniform dmat4 modelViewProjectionMatrix;
 
@@ -43,6 +45,7 @@ uniform dmat4 shadowMatrix;
 
 void main() {
   vs_st = in_st;
+  vs_normal = mat3(modelViewProjectionMatrix) * in_normal;
 
   dvec4 positionClipSpace  = modelViewProjectionMatrix * dvec4(in_position, 0.0, 1.0);
   vec4 positionClipSpaceZNorm = z_normalization(vec4(positionClipSpace));

modules/globebrowsing/shaders/rings_fs.glsl

@@ -31,6 +31,7 @@
 in vec2 vs_st;
 in float vs_screenSpaceDepth;
 in vec4 shadowCoords;
+in vec3 vs_normal;
 
 uniform sampler2DShadow shadowMapTexture;
 uniform sampler1D ringTexture;

modules/globebrowsing/shaders/rings_geom_fs.glsl

@@ -27,6 +27,7 @@
 
 in vec2 vs_st;
 in float vs_screenSpaceDepth;
+in vec3 vs_normal;
 
 uniform sampler1D ringTexture;
 uniform vec2 textureOffset;
@@ -39,6 +40,11 @@ Fragment getFragment() {
   // The length of the texture coordinates vector is our distance from the center
   float radius = length(st);
 
+  // Discard if normal is perpendicular to the camera direction
+  if (abs(dot(normalize(vs_normal), vec3(0.0, 0.0, 1.0))) <= 0.01) {
+    discard;
+  }
+
   // We only want to consider ring-like objects so we need to discard everything else
   if (radius > 1.0) {
     discard;

modules/globebrowsing/shaders/rings_geom_vs.glsl

@@ -28,15 +28,18 @@
 
 layout(location = 0) in vec2 in_position;
 layout(location = 1) in vec2 in_st;
+layout(location = 2) in vec3 in_normal;
 
 out vec2 vs_st;
 out float vs_screenSpaceDepth;
+out vec3 vs_normal;
 
 uniform dmat4 modelViewProjectionMatrix;
 
 
 void main() {
   vs_st = in_st;
+  vs_normal = mat3(modelViewProjectionMatrix) * in_normal;
 
   dvec4 positionClipSpace  = modelViewProjectionMatrix * dvec4(in_position, 0.0, 1.0);
   vec4 positionClipSpaceZNorm = z_normalization(vec4(positionClipSpace));

modules/globebrowsing/shaders/rings_vs.glsl

@@ -28,10 +28,12 @@
 
 layout(location = 0) in vec2 in_position;
 layout(location = 1) in vec2 in_st;
+layout(location = 2) in vec3 in_normal;
 
 out vec2 vs_st;
 out float vs_screenSpaceDepth;
 out vec4 shadowCoords;
+out vec3 vs_normal;
 
 uniform dmat4 modelViewProjectionMatrix;
 
@@ -43,6 +45,7 @@ uniform dmat4 shadowMatrix;
 
 void main() {
   vs_st = in_st;
+  vs_normal = mat3(modelViewProjectionMatrix) * in_normal;
 
   dvec4 positionClipSpace  = modelViewProjectionMatrix * dvec4(in_position, 0.0, 1.0);
   vec4 positionClipSpaceZNorm = z_normalization(vec4(positionClipSpace));

modules/globebrowsing/src/ringscomponent.cpp

@@ -769,15 +769,18 @@ void RingsComponent::createPlane() {
         GLfloat y;
         GLfloat s;
         GLfloat t;
+        GLfloat nx;
+        GLfloat ny;
+        GLfloat nz;
     };
 
     const std::array<VertexData, 6> vertices = {
-        VertexData{ -size, -size, 0.f, 0.f },
-        VertexData{  size,  size, 1.f, 1.f },
-        VertexData{ -size,  size, 0.f, 1.f },
-        VertexData{ -size, -size, 0.f, 0.f },
-        VertexData{  size, -size, 1.f, 0.f },
-        VertexData{  size,  size, 1.f, 1.f },
+        VertexData{ -size, -size, 0.f, 0.f, 0.f, 0.f, 1.f },
+        VertexData{  size,  size, 1.f, 1.f, 0.f, 0.f, 1.f },
+        VertexData{ -size,  size, 0.f, 1.f, 0.f, 0.f, 1.f },
+        VertexData{ -size, -size, 0.f, 0.f, 0.f, 0.f, 1.f },
+        VertexData{  size, -size, 1.f, 0.f, 0.f, 0.f, 1.f },
+        VertexData{  size,  size, 1.f, 1.f, 0.f, 0.f, 1.f },
     };
 
     glBindVertexArray(_quad);
@@ -801,6 +804,15 @@ void RingsComponent::createPlane() {
         sizeof(VertexData),
         reinterpret_cast<void*>(offsetof(VertexData, s))
     );
+    glEnableVertexAttribArray(2);
+    glVertexAttribPointer(
+        2,
+        3,
+        GL_FLOAT,
+        GL_FALSE,
+        sizeof(VertexData),
+        reinterpret_cast<void*>(offsetof(VertexData, nx))
+    );
 }
 
 void RingsComponent::compileShadowShader() {