Generate and use a shadow map

Generated when the directional light is specified in the environment call, passed to the directional
light shader pass to conditionally illuminate each pixel.

4 files changed, 32 insertions, 9 deletions

diff --git a/gfx/gl/sceneProvider.cpp b/gfx/gl/sceneProvider.cpp
index 9152bfa..8ff7d73 100644
--- a/gfx/gl/sceneProvider.cpp
+++ b/gfx/gl/sceneProvider.cpp
@@ -5,7 +5,7 @@ void
 SceneProvider::environment(const SceneShader &, const SceneRenderer & renderer) const
 {
 	renderer.setAmbientLight({0.5F, 0.5F, 0.5F});
-	renderer.setDirectionalLight({0.6F, 0.6F, 0.6F}, {1, 0, -1});
+	renderer.setDirectionalLight({0.6F, 0.6F, 0.6F}, {1, 0, -1}, *this);
 }
 void
 SceneProvider::shadows(const ShadowMapper &) const
diff --git a/gfx/gl/sceneRenderer.cpp b/gfx/gl/sceneRenderer.cpp
index a06a163..49c73a2 100644
--- a/gfx/gl/sceneRenderer.cpp
+++ b/gfx/gl/sceneRenderer.cpp
@@ -78,11 +78,15 @@ SceneRenderer::render(const SceneProvider & scene) const
 	glBindTexture(GL_TEXTURE_2D, gPosition);
 	glActiveTexture(GL_TEXTURE1);
 	glBindTexture(GL_TEXTURE_2D, gNormal);
+	glActiveTexture(GL_TEXTURE2);
+	glBindTexture(GL_TEXTURE_2D, shadowMapper);
 	scene.environment(shader, *this);
 	scene.lights(shader);
 
 	// Lighting pass
 	glBindFramebuffer(GL_FRAMEBUFFER, output);
+	glViewport(0, 0, size.x, size.y);
+	glCullFace(GL_BACK);
 	glDisable(GL_BLEND);
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 	glActiveTexture(GL_TEXTURE0);
@@ -102,32 +106,40 @@ SceneRenderer::render(const SceneProvider & scene) const
 void
 SceneRenderer::setAmbientLight(const glm::vec3 & colour) const
 {
+	glBindFramebuffer(GL_FRAMEBUFFER, gBuffer);
 	glClearColor(colour.r, colour.g, colour.b, 1.0F);
 	glClear(GL_COLOR_BUFFER_BIT);
 }
 
 void
-SceneRenderer::setDirectionalLight(const glm::vec3 & colour, const glm::vec3 & direction) const
+SceneRenderer::setDirectionalLight(
+		const glm::vec3 & colour, const glm::vec3 & direction, const SceneProvider & scene) const
 {
 	if (colour.r > 0 || colour.g > 0 || colour.b > 0) {
+		const auto lvp = shadowMapper.update(scene, direction);
+		glBindFramebuffer(GL_FRAMEBUFFER, gBuffer);
+		glViewport(0, 0, size.x, size.y);
 		dirLight.use();
-		dirLight.setDirectionalLight(colour, direction);
+		dirLight.setDirectionalLight(colour, direction, lvp);
 		glBindVertexArray(displayVAO);
 		glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 		glBindVertexArray(0);
+		glEnable(GL_DEPTH_TEST);
 	}
 }
 
 SceneRenderer::DirectionalLightProgram::DirectionalLightProgram() :
-	Program {lightingShader_vs, directionalLight_fs}, directionLoc {*this, "lightDirection"}, colourLoc {*this,
-																									  "lightColour"}
+	Program {lightingShader_vs, directionalLight_fs}, directionLoc {*this, "lightDirection"},
+	colourLoc {*this, "lightColour"}, lightViewProjectionLoc {*this, "lightViewProjection"}
 {
 }
 
 void
-SceneRenderer::DirectionalLightProgram::setDirectionalLight(const glm::vec3 & c, const glm::vec3 & d) const
+SceneRenderer::DirectionalLightProgram::setDirectionalLight(
+		const glm::vec3 & c, const glm::vec3 & d, const glm::mat4x4 & lvp) const
 {
 	glUniform3fv(colourLoc, 1, glm::value_ptr(c));
 	const auto nd = glm::normalize(d);
 	glUniform3fv(directionLoc, 1, glm::value_ptr(nd));
+	glUniformMatrix4fv(lightViewProjectionLoc, 1, GL_FALSE, glm::value_ptr(lvp));
 }
diff --git a/gfx/gl/sceneRenderer.h b/gfx/gl/sceneRenderer.h
index 736b15a..d7a92b7 100644
--- a/gfx/gl/sceneRenderer.h
+++ b/gfx/gl/sceneRenderer.h
@@ -5,6 +5,7 @@
 #include "program.h"
 #include "sceneProvider.h"
 #include "sceneShader.h"
+#include "shadowMapper.h"
 #include <functional>
 #include <glm/fwd.hpp>
 
@@ -14,7 +15,7 @@ public:
 
 	void render(const SceneProvider &) const;
 	void setAmbientLight(const glm::vec3 & colour) const;
-	void setDirectionalLight(const glm::vec3 & colour, const glm::vec3 & direction) const;
+	void setDirectionalLight(const glm::vec3 & colour, const glm::vec3 & direction, const SceneProvider &) const;
 
 	Camera camera;
 
@@ -34,10 +35,10 @@ private:
 		DirectionalLightProgram();
 		using Program::use;
 
-		void setDirectionalLight(const glm::vec3 &, const glm::vec3 &) const;
+		void setDirectionalLight(const glm::vec3 &, const glm::vec3 &, const glm::mat4x4 &) const;
 
 	private:
-		RequiredUniformLocation directionLoc, colourLoc;
+		RequiredUniformLocation directionLoc, colourLoc, lightViewProjectionLoc;
 	};
 
 	DeferredLightProgram lighting;
@@ -45,4 +46,5 @@ private:
 	glVertexArray displayVAO;
 	glBuffer displayVBO;
 	SceneShader shader;
+	ShadowMapper shadowMapper;
 };
diff --git a/gfx/gl/shaders/directionalLight.fs b/gfx/gl/shaders/directionalLight.fs
index 7562f96..5350bf3 100644
--- a/gfx/gl/shaders/directionalLight.fs
+++ b/gfx/gl/shaders/directionalLight.fs
@@ -5,14 +5,23 @@ out vec3 FragColor;
 
 in vec2 TexCoords;
 
+layout(binding = 0) uniform sampler2D gPosition;
 layout(binding = 1) uniform sampler2D gNormal;
+layout(binding = 2) uniform sampler2D shadowMap;
 
 uniform vec3 lightDirection;
 uniform vec3 lightColour;
+uniform mat4 lightViewProjection;
 
 void
 main()
 {
+	const vec3 Position = texture(gPosition, TexCoords).xyz;
+	const vec4 PositionInLightSpace = (lightViewProjection * vec4(Position, 1)) * 0.5 + 0.5;
+	const float lightSpaceDepth = texture(shadowMap, PositionInLightSpace.xy).r;
+	if (lightSpaceDepth < PositionInLightSpace.z) {
+		discard;
+	}
 	const vec3 Normal = texture(gNormal, TexCoords).rgb;
 	FragColor = dot(-lightDirection, Normal) * lightColour;
 }