Shaders: add an ability to control specular light color to Phong.

doc/changelog.dox

@@ -83,6 +83,8 @@ See also:
 -   @ref Shaders::Phong was reworked to support directional and
     range-attenuated point lights to follow the additions to
     @ref Trade::LightData
+-   Added @ref Shaders::Phong::setLightSpecularColors() for better control over
+    speculat highlights
 
 @subsubsection changelog-latest-new-scenegraph SceneGraph library
 

doc/snippets/MagnumShaders.cpp

@@ -546,6 +546,7 @@ shader
     .setLightColors({0xf0f0ff_srgbf*0.1f,
                      0xff8080_srgbf*10.0f,
                      0x80ff80_srgbf*10.0f})
+    .setLightColors(DOXYGEN_IGNORE({0xf0f0ff_srgbf}))
     .setLightRanges({Constants::inf(),
                      2.0f,
                      2.0f});

src/Magnum/Shaders/Phong.cpp

@@ -55,7 +55,7 @@ namespace {
     };
 }
 
-Phong::Phong(const Flags flags, const UnsignedInt lightCount): _flags{flags}, _lightCount{lightCount}, _lightColorsUniform{_lightPositionsUniform + Int(lightCount)}, _lightRangesUniform{_lightPositionsUniform + 2*Int(lightCount)} {
+Phong::Phong(const Flags flags, const UnsignedInt lightCount): _flags{flags}, _lightCount{lightCount}, _lightColorsUniform{_lightPositionsUniform + Int(lightCount)}, _lightSpecularColorsUniform{_lightPositionsUniform + 2*Int(lightCount)}, _lightRangesUniform{_lightPositionsUniform + 3*Int(lightCount)} {
     CORRADE_ASSERT(!(flags & Flag::TextureTransformation) || (flags & (Flag::AmbientTexture|Flag::DiffuseTexture|Flag::SpecularTexture|Flag::NormalTexture)),
         "Shaders::Phong: texture transformation enabled but the shader is not textured", );
 
@@ -156,10 +156,12 @@ Phong::Phong(const Flags flags, const UnsignedInt lightCount): _flags{flags}, _l
         .addSource(Utility::formatString(
             "#define LIGHT_COUNT {}\n"
             "#define LIGHT_COLORS_LOCATION {}\n"
+            "#define LIGHT_SPECULAR_COLORS_LOCATION {}\n"
             "#define LIGHT_RANGES_LOCATION {}\n",
             lightCount,
             _lightPositionsUniform + lightCount,
-            _lightPositionsUniform + 2*lightCount));
+            _lightPositionsUniform + 2*lightCount,
+            _lightPositionsUniform + 3*lightCount));
     #ifndef MAGNUM_TARGET_GLES
     if(lightCount) frag.addSource(std::move(lightInitializerFragment));
     #endif
@@ -224,6 +226,7 @@ Phong::Phong(const Flags flags, const UnsignedInt lightCount): _flags{flags}, _l
                 _normalTextureScaleUniform = uniformLocation("normalTextureScale");
             _lightPositionsUniform = uniformLocation("lightPositions");
             _lightColorsUniform = uniformLocation("lightColors");
+            _lightSpecularColorsUniform = uniformLocation("lightSpecularColors");
             _lightRangesUniform = uniformLocation("lightRanges");
         }
         if(flags & Flag::AlphaMask) _alphaMaskUniform = uniformLocation("alphaMask");
@@ -258,7 +261,9 @@ Phong::Phong(const Flags flags, const UnsignedInt lightCount): _flags{flags}, _l
         if(flags & Flag::NormalTexture)
             setNormalTextureScale(1.0f);
         setLightPositions(Containers::Array<Vector4>{Containers::DirectInit, lightCount, Vector4{0.0f, 0.0f, 1.0f, 0.0f}});
-        setLightColors(Containers::Array<Magnum::Color3>{Containers::DirectInit, lightCount, Magnum::Color3{1.0f}});
+        Containers::Array<Magnum::Color3> colors{Containers::DirectInit, lightCount, Magnum::Color3{1.0f}};
+        setLightColors(colors);
+        setLightSpecularColors(colors);
         setLightRanges(Containers::Array<Float>{Containers::DirectInit, lightCount, Constants::inf()});
         /* Light position is zero by default */
         setNormalMatrix({});
@@ -461,6 +466,24 @@ Phong& Phong::setLightColor(const Magnum::Color4& color) {
 }
 #endif
 
+Phong& Phong::setLightSpecularColors(const Containers::ArrayView<const Magnum::Color3> colors) {
+    CORRADE_ASSERT(_lightCount == colors.size(),
+        "Shaders::Phong::setLightSpecularColors(): expected" << _lightCount << "items but got" << colors.size(), *this);
+    if(_lightCount) setUniform(_lightSpecularColorsUniform, colors);
+    return *this;
+}
+
+Phong& Phong::setLightSpecularColors(const std::initializer_list<Magnum::Color3> colors) {
+    return setLightSpecularColors(Containers::arrayView(colors));
+}
+
+Phong& Phong::setLightSpecularColor(const UnsignedInt id, const Magnum::Color3& color) {
+    CORRADE_ASSERT(id < _lightCount,
+        "Shaders::Phong::setLightSpecularColor(): light ID" << id << "is out of bounds for" << _lightCount << "lights", *this);
+    setUniform(_lightSpecularColorsUniform + id, color);
+    return *this;
+}
+
 Phong& Phong::setLightRanges(const Containers::ArrayView<const Float> ranges) {
     CORRADE_ASSERT(_lightCount == ranges.size(),
         "Shaders::Phong::setLightRanges(): expected" << _lightCount << "items but got" << ranges.size(), *this);

src/Magnum/Shaders/Phong.frag

@@ -140,7 +140,8 @@ uniform highp uint objectId; /* defaults to zero */
 #if LIGHT_COUNT
 /* Needs to be last because it uses locations 11 + LIGHT_COUNT to
    11 + 2*LIGHT_COUNT - 1. Location 11 is lightPositions. Also it can't be
-   specified as 11 + LIGHT_COUNT because that requires ARB_enhanced_layouts. */
+   specified as 11 + LIGHT_COUNT because that requires ARB_enhanced_layouts.
+   Same for lightSpecularColors and lightRanges below. */
 #ifdef EXPLICIT_UNIFORM_LOCATION
 layout(location = LIGHT_COLORS_LOCATION) /* I fear this will blow up some drivers */
 #endif
@@ -150,6 +151,15 @@ uniform lowp vec3 lightColors[LIGHT_COUNT]
     #endif
     ;
 
+#ifdef EXPLICIT_UNIFORM_LOCATION
+layout(location = LIGHT_SPECULAR_COLORS_LOCATION)
+#endif
+uniform lowp vec3 lightSpecularColors[LIGHT_COUNT]
+    #ifndef GL_ES
+    = vec3[](LIGHT_COLOR_INITIALIZER)
+    #endif
+    ;
+
 #ifdef EXPLICIT_UNIFORM_LOCATION
 layout(location = LIGHT_RANGES_LOCATION)
 #endif
@@ -272,7 +282,7 @@ void main() {
             highp vec3 reflection = reflect(-normalizedLightDirection, normalizedTransformedNormal);
             /* Use attenuation for the specularity as well */
             mediump float specularity = clamp(pow(max(0.0, dot(normalize(cameraDirection), reflection)), shininess), 0.0, 1.0)*attenuation;
-            fragmentColor += vec4(finalSpecularColor.rgb*specularity, finalSpecularColor.a);
+            fragmentColor += vec4(finalSpecularColor.rgb*lightSpecularColors[i].rgb*specularity, finalSpecularColor.a);
         }
     }
     #endif

src/Magnum/Shaders/Phong.h

@@ -78,9 +78,10 @@ Common rendering setup:
 By default, the shader provides a single directional "fill" light, coming from
 the center of the camera. Using the @p lightCount parameter in constructor, you
 can specify how many lights you want, and then control light parameters using
-the following @ref setLightPositions(), @ref setLightColors() and
+@ref setLightPositions(), @ref setLightColors(), @ref setLightSpecularColors()
-@ref setLightRanges(). Light positions are specified as four-component vectors,
+and @ref setLightRanges(). Light positions are specified as four-component
-the last component distinguishing between directional and point lights.
+vectors, the last component distinguishing between directional and point
+lights.
 
 <ul><li>
 Point lights are specified with camera-relative position and the last component
@@ -106,7 +107,7 @@ any way: @f[
 
 Light color and intensity, corresponding to @ref Trade::LightData::color() and
 @ref Trade::LightData::intensity(), is meant to be multiplied together and
-passed to @ref setLightColors().
+passed to @ref setLightColors() and @ref setLightSpecularColors().
 
 The following example shows a three-light setup with one dim directional light
 shining from the top and two stronger but range-limited point lights:
@@ -941,6 +942,38 @@ class MAGNUM_SHADERS_EXPORT Phong: public GL::AbstractShaderProgram {
         CORRADE_DEPRECATED("use setLightColor(std::initializer_list<Color3>) instead") Phong& setLightColor(const Magnum::Color4& color);
         #endif
 
+        /**
+         * @brief Set light specular colors
+         * @return Reference to self (for method chaining)
+         * @m_since_latest
+         *
+         * Usually you'd set this value to the same as @ref setLightColors(),
+         * but it allows for greater flexibility such as disabling specular
+         * highlights on certain lights. Initial values are
+         * @cpp 0xffffff_rgbf @ce. Expects that the size of the @p colors array
+         * is the same as @ref lightCount().
+         * @see @ref Shaders-Phong-lights, @ref setLightColor()
+         */
+        Phong& setLightSpecularColors(Containers::ArrayView<const Magnum::Color3> colors);
+
+        /**
+         * @overload
+         * @m_since_latest
+         */
+        Phong& setLightSpecularColors(std::initializer_list<Magnum::Color3> colors);
+
+        /**
+         * @brief Set position for given light
+         * @return Reference to self (for method chaining)
+         * @m_since_latest
+         *
+         * Unlike @ref setLightSpecularColors() updates just a single light
+         * color. If updating more than one light, prefer the batch function
+         * instead to reduce the count of GL API calls. Expects that @p id is
+         * less than @ref lightCount().
+         */
+        Phong& setLightSpecularColor(UnsignedInt id, const Magnum::Color3& color);
+
         /**
          * @brief Set light attenuation ranges
          * @return Reference to self (for method chaining)
@@ -996,7 +1029,8 @@ class MAGNUM_SHADERS_EXPORT Phong: public GL::AbstractShaderProgram {
             #endif
         Int _lightPositionsUniform{11},
             _lightColorsUniform, /* 11 + lightCount, set in the constructor */
-            _lightRangesUniform; /* 11 + 2*lightCount, set in the constructor */
+            _lightSpecularColorsUniform, /* 11 + 2*lightCount */
+            _lightRangesUniform; /* 11 + 3*lightCount */
 };
 
 /** @debugoperatorclassenum{Phong,Phong::Flag} */

src/Magnum/Shaders/Test/CMakeLists.txt

@@ -246,6 +246,7 @@ if(BUILD_GL_TESTS)
             PhongTestFiles/light-point-attenuated-specular.tga
             PhongTestFiles/light-point-intensity10-range0.5.tga
             PhongTestFiles/light-point-range1.5.tga
+            PhongTestFiles/light-point-specular-color.tga
             PhongTestFiles/light-point.tga
 
             # For zero lights test (equivalency to Flat3D)

src/Magnum/Shaders/Test/PhongGLTest.cpp

@@ -344,12 +344,14 @@ const struct {
     const char* name;
     const char* file;
     Vector4 position;
+    Color3 specularColor, lightSpecularColor;
     Float intensity;
     Float range;
     Containers::Array<std::pair<Vector2i, Color3ub>> picks;
 } RenderLightsData[] {
     {"directional", "light-directional.tga",
-        {1.0f, -1.5f, 0.5f, 0.0f}, 1.0f, Constants::inf(),
+        {1.0f, -1.5f, 0.5f, 0.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, Constants::inf(),
         {Containers::InPlaceInit, {
             /* Ambient isn't affected by light direction, otherwise it's a
                dot product of a normalized direction */
@@ -360,18 +362,23 @@ const struct {
     /* These two should produce the same output as the *normalized* dot product
        is the same */
     {"directional, from the other side", "light-directional.tga",
-        {-1.0f, 1.5f, 0.5f, 0.0f}, 1.0f, Constants::inf(), {}},
+        {-1.0f, 1.5f, 0.5f, 0.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, Constants::inf(), {}},
     {"directional, scaled direction", "light-directional.tga",
-        {10.0f, -15.0f, 5.0f, 0.0f}, 1.0f, Constants::inf(), {}},
+        {10.0f, -15.0f, 5.0f, 0.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, Constants::inf(), {}},
     /* Range should have no effect either, especially zero range should not
        cause any NaNs */
     {"directional, range=0.1", "light-directional.tga",
-        {1.0f, -1.5f, 0.5f, 0.0f}, 1.0f, 1.0f, {}},
+        {1.0f, -1.5f, 0.5f, 0.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, 1.0f, {}},
     {"directional, range=0", "light-directional.tga",
-        {1.0f, -1.5f, 0.5f, 0.0f}, 1.0f, 1.0f, {}},
+        {1.0f, -1.5f, 0.5f, 0.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, 1.0f, {}},
     /* Light from the other side doesn't contribute anything */
     {"directional, from back", "light-none.tga",
-        {-1.0f, 1.5f, -0.5f, 0.0f}, 1.0f, Constants::inf(),
+        {-1.0f, 1.5f, -0.5f, 0.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, Constants::inf(),
         {Containers::InPlaceInit, {
             /* Only ambient color left */
             {{40, 40}, 0x222222_rgb}
@@ -379,12 +386,14 @@ const struct {
     /* This is the same as above, except that twice the intensity causes it to
        be 2x brighter */
     {"directional, intensity=2", "light-directional-intensity2.tga",
-        {1.0f, -1.5f, 0.5f, 0.0f}, 2.0f, 1.0f,
+        {1.0f, -1.5f, 0.5f, 0.0f}, Color3{1.0f}, Color3{1.0f},
+        2.0f, 1.0f,
         {Containers::InPlaceInit, {
             {{40, 40}, 0x222222_rgb + 0xff8080_rgb*dot(Vector3{1.0f, -1.5f, 0.5f}.normalized(), Vector3::zAxis())*2.0f}
         }}},
     {"point", "light-point.tga",
-        {0.75f, -0.75f, -1.25f, 1.0f}, 1.0f, Constants::inf(),
+        {0.75f, -0.75f, -1.25f, 1.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, Constants::inf(),
         {Containers::InPlaceInit, {
             /* The range is inf, so it doesn't get fully ambient even at the
                edge */
@@ -394,15 +403,31 @@ const struct {
             /* Specular highlight */
             {{60, 19}, 0xfefefe_rgb}
         }}},
+    {"point, specular material color", "light-point-specular-color.tga",
+        {0.75f, -0.75f, -1.25f, 1.0f}, 0x80ff80_rgbf, Color3{1.0f},
+        1.0f, Constants::inf(),
+        {Containers::InPlaceInit, {
+            /* Colored specular highlight */
+            {{60, 19}, 0xf2fcb0_rgb}
+        }}},
+    {"point, specular light color", "light-point-specular-color.tga",
+        {0.75f, -0.75f, -1.25f, 1.0f}, Color3{1.0f}, 0x80ff80_rgbf,
+        1.0f, Constants::inf(),
+        {Containers::InPlaceInit, {
+            /* Colored specular highlight */
+            {{60, 19}, 0xf2fcb0_rgb}
+        }}},
     {"point, attenuated specular", "light-point-attenuated-specular.tga",
-        {1.0f, -1.0f, -0.25f, 1.0f}, 1.0f, 2.5f,
+        {1.0f, -1.0f, -0.25f, 1.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, 2.5f,
         {Containers::InPlaceInit, {
             /* Specular highlight shouldn't be brighter than the attenuated
                intensity */
             {{57, 22}, 0x665656_rgb}
         }}},
-    {"point, range=1.5", "light-point-range1.5.tga",
+    {"point, range=1.5, specular color", "light-point-range1.5.tga",
-        {0.75f, -0.75f, -1.25f, 1.0f}, 1.0f, 1.5f,
+        {0.75f, -0.75f, -1.25f, 1.0f}, Color3{1.0f}, 0x80ff80_rgbf,
+        1.0f, 1.5f,
         {Containers::InPlaceInit, {
             /* Color goes back to ambient at distance = 1.5 */
             {{59, 60}, 0x222222_rgb},
@@ -410,21 +435,25 @@ const struct {
             {{19, 14}, 0x222222_rgb},
             /* But the center and specular stays ~ the same */
             {{63, 16}, 0xc57474_rgb},
-            {{60, 19}, 0xfefcfc_rgb}
+            {{60, 19}, 0xf2fcb0_rgb}
         }}},
     {"point, intensity=10, range=0.5", "light-point-intensity10-range0.5.tga",
-        {0.75f, -0.75f, -1.25f, 1.0f}, 10.0f, 0.5f, {}},
+        {0.75f, -0.75f, -1.25f, 1.0f}, Color3{1.0f}, Color3{1.0f},
+        10.0f, 0.5f, {}},
     /* Range ends right at the surface, so no contribution */
     {"point, range=0.25", "light-none.tga",
-        {0.75f, -0.75f, -1.25f, 1.0f}, 1.0f, 0.25f, {}},
+        {0.75f, -0.75f, -1.25f, 1.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, 0.25f, {}},
     /* Zero range should not cause any NaNs, so the ambient contribution is
        still there */
     {"point, range=0.0", "light-none.tga",
-        {0.75f, -0.75f, -1.25f, 1.0f}, 1.0f, 0.0f, {}},
+        {0.75f, -0.75f, -1.25f, 1.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, 0.0f, {}},
     /* Distance is 0, which means the direction is always prependicular and
        thus contributes nothing */
     {"point, distance=0", "light-none.tga",
-        {0.75f, -0.75f, -1.25f, 1.0f}, 1.0f, 0.0f, {}}
+        {0.75f, -0.75f, -1.25f, 1.0f}, Color3{1.0f}, Color3{1.0f},
+        1.0f, 0.0f, {}}
 };
 
 constexpr struct {
@@ -1476,8 +1505,10 @@ void PhongGLTest::renderLights() {
         /* Set non-black ambient to catch accidental NaNs -- the render should
            never be fully black */
         .setAmbientColor(0x222222_rgbf)
+        .setSpecularColor(data.specularColor)
         .setLightPositions({data.position})
         .setLightColors({0xff8080_rgbf*data.intensity})
+        .setLightSpecularColors({data.lightSpecularColor})
         .setLightRanges({data.range})
         .setShininess(60.0f)
         .setTransformationMatrix(transformation)
@@ -1531,6 +1562,8 @@ void PhongGLTest::renderLightsSetOneByOne() {
         .setLightPosition(1, {0.75f, -0.75f, -1.25f, 1.0f})
         .setLightColor(0, 0x00ffff_rgbf)
         .setLightColor(1, 0xff8080_rgbf)
+        .setLightSpecularColor(0, 0x0000ff_rgbf)
+        .setLightSpecularColor(1, 0x80ff80_rgbf)
         .setLightRange(0, Constants::inf())
         .setLightRange(1, 1.5f)
         .setShininess(60.0f)