Shaders: support multiple lights in Phong.

doc/changelog.dox

@@ -138,6 +138,7 @@ See also:
 -   New dedicated @ref Shaders::VertexColor::Color3 and
     @ref Shaders::VertexColor::Color4 attribute specifiers for more convenient
     distinction between three- and four-component vertex color attribute.
+-   Support for multiple lights in @ref Shaders::Phong
 -   Classical alpha masking support in @ref Shaders::Flat and
     @ref Shaders::Phong
 -   Debug output for the @ref Shaders::Flat::Flag / @ref Shaders::Flat::Flags,

src/Magnum/Shaders/Phong.cpp

@@ -25,7 +25,11 @@
 
 #include "Phong.h"
 
+#ifdef MAGNUM_TARGET_GLES
+#include <Corrade/Containers/Array.h>
+#endif
 #include <Corrade/Containers/EnumSet.hpp>
+#include <Corrade/Utility/Format.h>
 #include <Corrade/Utility/Resource.h>
 
 #include "Magnum/GL/Context.h"
@@ -45,7 +49,7 @@ namespace {
     };
 }
 
-Phong::Phong(const Flags flags): _flags(flags) {
+Phong::Phong(const Flags flags, const UnsignedInt lightCount): _flags{flags}, _lightCount{lightCount}, _lightColorsUniform{9 + Int(lightCount)} {
     #ifdef MAGNUM_BUILD_STATIC
     /* Import resources on static build, if not already */
     if(!Utility::Resource::hasGroup("MagnumShaders"))
@@ -62,13 +66,40 @@ Phong::Phong(const Flags flags): _flags(flags) {
     GL::Shader vert = Implementation::createCompatibilityShader(rs, version, GL::Shader::Type::Vertex);
     GL::Shader frag = Implementation::createCompatibilityShader(rs, version, GL::Shader::Type::Fragment);
 
+    #ifndef MAGNUM_TARGET_GLES
+    /* Initializer for the light color array -- we need a list of vec4(1.0)
+       joined by commas. For GLES we'll simply upload the values directly. */
+    constexpr const char lightInitializerPreamble[] = "#define LIGHT_COLOR_INITIALIZER ";
+    constexpr std::size_t lightInitializerPreambleSize =
+        Containers::arraySize(lightInitializerPreamble) - 1;
+    constexpr const char lightInitializerItem[] = "vec4(1.0), ";
+    constexpr std::size_t lightInitializerItemSize =
+        Containers::arraySize(lightInitializerItem) - 1;
+    std::string lightInitializer;
+    lightInitializer.reserve(Containers::arraySize(lightInitializerPreamble) - 1 + lightCount*lightInitializerItemSize);
+    lightInitializer.append(lightInitializerPreamble, lightInitializerPreambleSize);
+    for(std::size_t i = 0; i != lightCount; ++i)
+        lightInitializer.append(lightInitializerItem, lightInitializerItemSize);
+
+    /* Drop the last comma and add a newline at the end */
+    lightInitializer[lightInitializer.size() - 2] = '\n';
+    lightInitializer.resize(lightInitializer.size() - 1);
+    #endif
+
     vert.addSource(flags ? "#define TEXTURED\n" : "")
+        .addSource(Utility::formatString("#define LIGHT_COUNT {}\n", lightCount))
         .addSource(rs.get("generic.glsl"))
         .addSource(rs.get("Phong.vert"));
     frag.addSource(flags & Flag::AmbientTexture ? "#define AMBIENT_TEXTURE\n" : "")
         .addSource(flags & Flag::DiffuseTexture ? "#define DIFFUSE_TEXTURE\n" : "")
         .addSource(flags & Flag::SpecularTexture ? "#define SPECULAR_TEXTURE\n" : "")
         .addSource(flags & Flag::AlphaMask ? "#define ALPHA_MASK\n" : "")
+        .addSource(Utility::formatString(
+            "#define LIGHT_COUNT {}\n"
+            "#define LIGHT_COLORS_LOCATION {}\n", lightCount, 9 + lightCount))
+        #ifndef MAGNUM_TARGET_GLES
+        .addSource(std::move(lightInitializer))
+        #endif
         .addSource(rs.get("Phong.frag"));
 
     CORRADE_INTERNAL_ASSERT_OUTPUT(GL::Shader::compile({vert, frag}));
@@ -96,13 +127,13 @@ Phong::Phong(const Flags flags): _flags(flags) {
         _transformationMatrixUniform = uniformLocation("transformationMatrix");
         _projectionMatrixUniform = uniformLocation("projectionMatrix");
         _normalMatrixUniform = uniformLocation("normalMatrix");
-        _lightPositionUniform = uniformLocation("lightPosition");
         _ambientColorUniform = uniformLocation("ambientColor");
         _diffuseColorUniform = uniformLocation("diffuseColor");
         _specularColorUniform = uniformLocation("specularColor");
-        _lightColorUniform = uniformLocation("lightColor");
         _shininessUniform = uniformLocation("shininess");
         if(flags & Flag::AlphaMask) _alphaMaskUniform = uniformLocation("alphaMask");
+        _lightPositionsUniform = uniformLocation("lightPositions");
+        _lightColorsUniform = uniformLocation("lightColors");
     }
 
     #ifndef MAGNUM_TARGET_GLES
@@ -121,9 +152,9 @@ Phong::Phong(const Flags flags): _flags(flags) {
     else setAmbientColor(Color4{0.0f});
     setDiffuseColor(Color4{1.0f});
     setSpecularColor(Color4{1.0f});
-    setLightColor(Color4{1.0f});
     setShininess(80.0f);
     if(flags & Flag::AlphaMask) setAlphaMask(0.5f);
+    setLightColors(Containers::Array<Color4>{Containers::DirectInit, lightCount, Color4{1.0f}});
 
     setTransformationMatrix({});
     setProjectionMatrix({});
@@ -174,6 +205,13 @@ Phong& Phong::setLightPositions(const Containers::ArrayView<const Vector3> posit
     return *this;
 }
 
+Phong& Phong::setLightPosition(UnsignedInt id, const Vector3& position) {
+    CORRADE_ASSERT(id < _lightCount,
+        "Shaders::Phong::setLightPosition(): light ID" << id << "is out of bounds for" << _lightCount << "lights", *this);
+    setUniform(_lightPositionsUniform + id, position);
+    return *this;
+}
+
 Phong& Phong::setLightColors(const Containers::ArrayView<const Color4> colors) {
     CORRADE_ASSERT(_lightCount == colors.size(),
         "Shaders::Phong::setLightColors(): expected" << _lightCount << "items but got" << colors.size(), *this);
@@ -181,6 +219,13 @@ Phong& Phong::setLightColors(const Containers::ArrayView<const Color4> colors) {
     return *this;
 }
 
+Phong& Phong::setLightColor(UnsignedInt id, const Color4& color) {
+    CORRADE_ASSERT(id < _lightCount,
+        "Shaders::Phong::setLightColor(): light ID" << id << "is out of bounds for" << _lightCount << "lights", *this);
+    setUniform(_lightColorsUniform + id, color);
+    return *this;
+}
+
 Debug& operator<<(Debug& debug, const Phong::Flag value) {
     switch(value) {
         /* LCOV_EXCL_START */

src/Magnum/Shaders/Phong.frag

@@ -88,34 +88,37 @@ uniform lowp vec4 specularColor
 #ifdef EXPLICIT_UNIFORM_LOCATION
 layout(location = 7)
 #endif
-uniform lowp vec4 lightColor
+uniform mediump float shininess
     #ifndef GL_ES
-    = vec4(1.0)
+    = 80.0
     #endif
     ;
 
+#ifdef ALPHA_MASK
 #ifdef EXPLICIT_UNIFORM_LOCATION
 layout(location = 8)
 #endif
-uniform mediump float shininess
+uniform lowp float alphaMask
     #ifndef GL_ES
-    = 80.0
+    = 0.5
     #endif
     ;
+#endif
 
-#ifdef ALPHA_MASK
+/* Needs to be last because it uses locations 9 + LIGHT_COUNT to
+   9 + 2*LIGHT_COUNT - 1. Location 9 is lightPositions. Also it can't be
+   specified as 9 + LIGHT_COUNT because that requires ARB_enhanced_layouts. */
 #ifdef EXPLICIT_UNIFORM_LOCATION
-layout(location = 9)
+layout(location = LIGHT_COLORS_LOCATION) /* I fear this will blow up some drivers */
 #endif
-uniform lowp float alphaMask
+uniform lowp vec4 lightColors[LIGHT_COUNT]
     #ifndef GL_ES
-    = 0.5
+    = vec4[](LIGHT_COLOR_INITIALIZER)
     #endif
     ;
-#endif
 
 in mediump vec3 transformedNormal;
-in highp vec3 lightDirection;
+in highp vec3 lightDirections[LIGHT_COUNT];
 in highp vec3 cameraDirection;
 
 #if defined(AMBIENT_TEXTURE) || defined(DIFFUSE_TEXTURE) || defined(SPECULAR_TEXTURE)
@@ -147,17 +150,19 @@ void main() {
     color = finalAmbientColor;
 
     mediump vec3 normalizedTransformedNormal = normalize(transformedNormal);
-    highp vec3 normalizedLightDirection = normalize(lightDirection);
-
-    /* Add diffuse color */
-    lowp float intensity = max(0.0, dot(normalizedTransformedNormal, normalizedLightDirection));
-    color += vec4(finalDiffuseColor.rgb*lightColor.rgb*intensity, lightColor.a*finalDiffuseColor.a);
 
-    /* Add specular color, if needed */
-    if(intensity > 0.001) {
-        highp vec3 reflection = reflect(-normalizedLightDirection, normalizedTransformedNormal);
-        mediump float specularity = pow(max(0.0, dot(normalize(cameraDirection), reflection)), shininess);
-        color += vec4(finalSpecularColor.rgb*specularity, finalSpecularColor.a);
+    /* Add diffuse color for each light */
+    for(int i = 0; i < LIGHT_COUNT; ++i) {
+        highp vec3 normalizedLightDirection = normalize(lightDirections[i]);
+        lowp float intensity = max(0.0, dot(normalizedTransformedNormal, normalizedLightDirection));
+        color += vec4(finalDiffuseColor.rgb*lightColors[i].rgb*intensity, lightColors[i].a*finalDiffuseColor.a);
+
+        /* Add specular color, if needed */
+        if(intensity > 0.001) {
+            highp vec3 reflection = reflect(-normalizedLightDirection, normalizedTransformedNormal);
+            mediump float specularity = pow(max(0.0, dot(normalize(cameraDirection), reflection)), shininess);
+            color += vec4(finalSpecularColor.rgb*specularity, finalSpecularColor.a);
+        }
     }
 
     #ifdef ALPHA_MASK

src/Magnum/Shaders/Phong.h

@@ -172,9 +172,10 @@ class MAGNUM_SHADERS_EXPORT Phong: public GL::AbstractShaderProgram {
 
         /**
          * @brief Constructor
-         * @param flags     Flags
+         * @param flags         Flags
+         * @param lightCount    Count of light sources
          */
-        explicit Phong(Flags flags = {});
+        explicit Phong(Flags flags = {}, UnsignedInt lightCount = 1);
 
         /**
          * @brief Construct without creating the underlying OpenGL object
@@ -203,6 +204,9 @@ class MAGNUM_SHADERS_EXPORT Phong: public GL::AbstractShaderProgram {
         /** @brief Flags */
         Flags flags() const { return _flags; }
 
+        /** @brief Light count */
+        UnsignedInt lightCount() const { return _lightCount; }
+
         /**
          * @brief Set ambient color
          * @return Reference to self (for method chaining)
@@ -387,42 +391,95 @@ class MAGNUM_SHADERS_EXPORT Phong: public GL::AbstractShaderProgram {
             return *this;
         }
 
+        /**
+         * @brief Set light positions
+         * @return Reference to self (for method chaining)
+         *
+         * Initial values are zero vectors --- that will in most cases cause
+         * the object to be rendered black (or in the ambient color), as the
+         * lights are is inside of it. Expects that the size of the @p lights
+         * array is the same as @ref lightCount().
+         * @see @ref setLightPosition(UnsignedInt, const Vector3&),
+         *      @ref setLightPosition(const Vector3&)
+         */
+        Phong& setLightPositions(Containers::ArrayView<const Vector3> lights);
+
+        /** @overload */
+        Phong& setLightPositions(std::initializer_list<Vector3> lights) {
+            return setLightPositions({lights.begin(), lights.size()});
+        }
+
+        /**
+         * @brief Set position for given light
+         * @return Reference to self (for method chaining)
+         *
+         * Unlike @ref setLightPosition() updates just a single light position.
+         * Expects that @p id is less than @ref lightCount().
+         * @see @ref setLightPosition(const Vector3&)
+         */
+        Phong& setLightPosition(UnsignedInt id, const Vector3& position);
+
         /**
          * @brief Set light position
          * @return Reference to self (for method chaining)
          *
-         * Initial value is a zero vector --- that will in most cases cause the
-         * object to be rendered black (or in the ambient color), as the light
-         * is inside of it.
+         * Convenience alternative to @ref setLightPositions() when there is
+         * just one light.
+         * @see @ref setLightPosition(UnsignedInt, const Vector3&)
          */
-        Phong& setLightPosition(const Vector3& light) {
-            setUniform(_lightPositionUniform, light);
-            return *this;
+        Phong& setLightPosition(const Vector3& position) {
+            return setLightPositions({&position, 1});
         }
 
+        /**
+         * @brief Set light colors
+         * @return Reference to self (for method chaining)
+         *
+         * Initial values are @cpp 0xffffffff_rgbaf @ce. Expects that the size
+         * of the @p colors array is the same as @ref lightCount().
+         */
+        Phong& setLightColors(Containers::ArrayView<const Color4> colors);
+
+        /** @overload */
+        Phong& setLightColors(std::initializer_list<Color4> colors) {
+            return setLightColors({colors.begin(), colors.size()});
+        }
+
+        /**
+         * @brief Set position for given light
+         * @return Reference to self (for method chaining)
+         *
+         * Unlike @ref setLightColors() updates just a single light color.
+         * Expects that @p id is less than @ref lightCount().
+         * @see @ref setLightColor(const Color4&)
+         */
+        Phong& setLightColor(UnsignedInt id, const Color4& color);
+
         /**
          * @brief Set light color
          * @return Reference to self (for method chaining)
          *
-         * Initial value is @cpp 0xffffffff_rgbaf @ce.
+         * Convenience alternative to @ref setLightColors() when there is just
+         * one light.
+         * @see @ref setLightColor(UnsignedInt, const Color4&)
          */
         Phong& setLightColor(const Color4& color) {
-            setUniform(_lightColorUniform, color);
-            return *this;
+            return setLightColors({&color, 1});
         }
 
     private:
         Flags _flags;
+        UnsignedInt _lightCount;
         Int _transformationMatrixUniform{0},
             _projectionMatrixUniform{1},
             _normalMatrixUniform{2},
-            _lightPositionUniform{3},
             _ambientColorUniform{4},
             _diffuseColorUniform{5},
             _specularColorUniform{6},
-            _lightColorUniform{7},
-            _shininessUniform{8},
-            _alphaMaskUniform{9};
+            _shininessUniform{7},
+            _alphaMaskUniform{8},
+            _lightPositionsUniform{9},
+            _lightColorsUniform; /* 9 + lightCount, set in the constructor */
 };
 
 /** @debugoperatorclassenum{Phong,Phong::Flag} */

src/Magnum/Shaders/Phong.vert

@@ -55,10 +55,11 @@ uniform mediump mat3 normalMatrix
     #endif
     ;
 
+/* Needs to be last because it uses locations 9 to 9 + LIGHT_COUNT - 1 */
 #ifdef EXPLICIT_UNIFORM_LOCATION
-layout(location = 3)
+layout(location = 9)
 #endif
-uniform highp vec3 lightPosition; /* defaults to zero */
+uniform highp vec3 lightPositions[LIGHT_COUNT]; /* defaults to zero */
 
 #ifdef EXPLICIT_ATTRIB_LOCATION
 layout(location = POSITION_ATTRIBUTE_LOCATION)
@@ -80,7 +81,7 @@ out mediump vec2 interpolatedTextureCoords;
 #endif
 
 out mediump vec3 transformedNormal;
-out highp vec3 lightDirection;
+out highp vec3 lightDirections[LIGHT_COUNT];
 out highp vec3 cameraDirection;
 
 void main() {
@@ -92,7 +93,8 @@ void main() {
     transformedNormal = normalMatrix*normal;
 
     /* Direction to the light */
-    lightDirection = normalize(lightPosition - transformedPosition);
+    for(int i = 0; i < LIGHT_COUNT; ++i)
+        lightDirections[i] = normalize(lightPositions[i] - transformedPosition);
 
     /* Direction to the camera */
     cameraDirection = -transformedPosition;

src/Magnum/Shaders/Test/PhongGLTest.cpp

@@ -46,22 +46,27 @@ struct PhongGLTest: GL::OpenGLTester {
 
     void setAlphaMask();
     void setAlphaMaskNotEnabled();
+
+    void setWrongLightCount();
+    void setWrongLightId();
 };
 
 constexpr struct {
     const char* name;
     Phong::Flags flags;
+    UnsignedInt lightCount;
 } ConstructData[]{
-    {"", {}},
-    {"ambient texture", Phong::Flag::AmbientTexture},
-    {"diffuse texture", Phong::Flag::DiffuseTexture},
-    {"specular texture", Phong::Flag::SpecularTexture},
-    {"ambient + diffuse texture", Phong::Flag::AmbientTexture|Phong::Flag::DiffuseTexture},
-    {"ambient + specular texture", Phong::Flag::AmbientTexture|Phong::Flag::SpecularTexture},
-    {"diffuse + specular texture", Phong::Flag::DiffuseTexture|Phong::Flag::SpecularTexture},
-    {"ambient + diffuse + specular texture", Phong::Flag::AmbientTexture|Phong::Flag::DiffuseTexture|Phong::Flag::SpecularTexture},
-    {"alpha mask", Phong::Flag::AlphaMask},
-    {"alpha mask + diffuse texture", Phong::Flag::AlphaMask|Phong::Flag::DiffuseTexture}
+    {"", {}, 1},
+    {"ambient texture", Phong::Flag::AmbientTexture, 1},
+    {"diffuse texture", Phong::Flag::DiffuseTexture, 1},
+    {"specular texture", Phong::Flag::SpecularTexture, 1},
+    {"ambient + diffuse texture", Phong::Flag::AmbientTexture|Phong::Flag::DiffuseTexture, 1},
+    {"ambient + specular texture", Phong::Flag::AmbientTexture|Phong::Flag::SpecularTexture, 1},
+    {"diffuse + specular texture", Phong::Flag::DiffuseTexture|Phong::Flag::SpecularTexture, 1},
+    {"ambient + diffuse + specular texture", Phong::Flag::AmbientTexture|Phong::Flag::DiffuseTexture|Phong::Flag::SpecularTexture, 1},
+    {"alpha mask", Phong::Flag::AlphaMask, 1},
+    {"alpha mask + diffuse texture", Phong::Flag::AlphaMask|Phong::Flag::DiffuseTexture, 1},
+    {"five lights", {}, 5}
 };
 
 PhongGLTest::PhongGLTest() {
@@ -73,15 +78,19 @@ PhongGLTest::PhongGLTest() {
               &PhongGLTest::bindTexturesNotEnabled,
 
               &PhongGLTest::setAlphaMask,
-              &PhongGLTest::setAlphaMaskNotEnabled});
+              &PhongGLTest::setAlphaMaskNotEnabled,
+
+              &PhongGLTest::setWrongLightCount,
+              &PhongGLTest::setWrongLightId});
 }
 
 void PhongGLTest::construct() {
     auto&& data = ConstructData[testCaseInstanceId()];
     setTestCaseDescription(data.name);
 
-    Phong shader{data.flags};
+    Phong shader{data.flags, data.lightCount};
     CORRADE_COMPARE(shader.flags(), data.flags);
+    CORRADE_COMPARE(shader.lightCount(), data.lightCount);
     {
         #ifdef CORRADE_TARGET_APPLE
         CORRADE_EXPECT_FAIL("macOS drivers need insane amount of state to validate properly.");
@@ -92,7 +101,7 @@ void PhongGLTest::construct() {
 }
 
 void PhongGLTest::constructMove() {
-    Phong a{Phong::Flag::AlphaMask};
+    Phong a{Phong::Flag::AlphaMask, 3};
     const GLuint id = a.id();
     CORRADE_VERIFY(id);
 
@@ -101,12 +110,14 @@ void PhongGLTest::constructMove() {
     Phong b{std::move(a)};
     CORRADE_COMPARE(b.id(), id);
     CORRADE_COMPARE(b.flags(), Phong::Flag::AlphaMask);
+    CORRADE_COMPARE(b.lightCount(), 3);
     CORRADE_VERIFY(!a.id());
 
     Phong c{NoCreate};
     c = std::move(b);
     CORRADE_COMPARE(c.id(), id);
     CORRADE_COMPARE(c.flags(), Phong::Flag::AlphaMask);
+    CORRADE_COMPARE(c.lightCount(), 3);
     CORRADE_VERIFY(!b.id());
 }
 
@@ -169,6 +180,48 @@ void PhongGLTest::setAlphaMaskNotEnabled() {
         "Shaders::Phong::setAlphaMask(): the shader was not created with alpha mask enabled\n");
 }
 
+void PhongGLTest::setWrongLightCount() {
+    std::ostringstream out;
+    Error redirectError{&out};
+
+    Phong shader{{}, 5};
+
+    /* This is okay */
+    shader.setLightColors({{}, {}, {}, {}, {}})
+        .setLightPositions({{}, {}, {}, {}, {}});
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    /* This is not */
+    shader.setLightColor({})
+        .setLightPosition({});
+
+    CORRADE_COMPARE(out.str(),
+        "Shaders::Phong::setLightColors(): expected 5 items but got 1\n"
+        "Shaders::Phong::setLightPositions(): expected 5 items but got 1\n");
+}
+
+void PhongGLTest::setWrongLightId() {
+    std::ostringstream out;
+    Error redirectError{&out};
+
+    Phong shader{{}, 3};
+
+    /* This is okay */
+    shader.setLightColor(2, {})
+        .setLightPosition(2, {});
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    /* This is not */
+    shader.setLightColor(3, {})
+        .setLightPosition(3, {});
+
+    CORRADE_COMPARE(out.str(),
+        "Shaders::Phong::setLightColor(): light ID 3 is out of bounds for 3 lights\n"
+        "Shaders::Phong::setLightPosition(): light ID 3 is out of bounds for 3 lights\n");
+}
+
 }}}
 
 CORRADE_TEST_MAIN(Magnum::Shaders::Test::PhongGLTest)