Add rendering support for spot lights

5 files changed, 166 insertions, 2 deletions

diff --git a/gfx/gl/sceneShader.cpp b/gfx/gl/sceneShader.cpp
index d0b26c8..981e7df 100644
--- a/gfx/gl/sceneShader.cpp
+++ b/gfx/gl/sceneShader.cpp
@@ -3,11 +3,14 @@
 #include <gfx/gl/shaders/fs-basicShader.h>
 #include <gfx/gl/shaders/fs-landmassShader.h>
 #include <gfx/gl/shaders/fs-pointLight.h>
+#include <gfx/gl/shaders/fs-spotLight.h>
 #include <gfx/gl/shaders/fs-waterShader.h>
 #include <gfx/gl/shaders/gs-pointLight.h>
+#include <gfx/gl/shaders/gs-spotLight.h>
 #include <gfx/gl/shaders/vs-basicShader.h>
 #include <gfx/gl/shaders/vs-landmassShader.h>
 #include <gfx/gl/shaders/vs-pointLight.h>
+#include <gfx/gl/shaders/vs-spotLight.h>
 #include <gfx/gl/shaders/vs-waterShader.h>
 #include <gfx/gl/vertexArrayObject.hpp>
 #include <glm/gtc/type_ptr.hpp>
@@ -23,7 +26,8 @@ SceneShader::SceneShader() :
 void
 SceneShader::setViewProjection(const glm::mat4 & viewProjection) const
 {
-	for (const auto & prog : std::array<const SceneProgram *, 5> {&basic, &water, &landmass, &absolute, &pointLight}) {
+	for (const auto & prog :
+			std::array<const SceneProgram *, 6> {&basic, &water, &landmass, &absolute, &pointLight, &spotLight}) {
 		prog->setViewProjection(viewProjection);
 	}
 }
@@ -31,7 +35,8 @@ SceneShader::setViewProjection(const glm::mat4 & viewProjection) const
 void
 SceneShader::setViewPort(const glm::ivec4 & viewPort) const
 {
-	for (const auto & prog : std::array<const SceneProgram *, 5> {&basic, &water, &landmass, &absolute, &pointLight}) {
+	for (const auto & prog :
+			std::array<const SceneProgram *, 6> {&basic, &water, &landmass, &absolute, &pointLight, &spotLight}) {
 		prog->setViewPort(viewPort);
 	}
 }
@@ -95,3 +100,26 @@ SceneShader::PointLightShader::add(const glm::vec3 & position, const glm::vec3 &
 	glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(glm::vec3), glm::value_ptr(position));
 	glDrawArrays(GL_POINTS, 0, 1);
 }
+
+SceneShader::SpotLightShader::SpotLightShader() :
+	SceneProgram {spotLight_vs, spotLight_gs, spotLight_fs}, colourLoc {*this, "colour"}, kqLoc {*this, "kq"},
+	arcLoc {*this, "arc"}
+{
+	using v3pair = std::pair<glm::vec3, glm::vec3>;
+	VertexArrayObject<v3pair>::configure<&v3pair::first, &v3pair::second>(va, b);
+}
+
+void
+SceneShader::SpotLightShader::add(const glm::vec3 & position, const glm::vec3 & direction, const glm::vec3 & colour,
+		const float kq, const float arc) const
+{
+	Program::use();
+	glBindVertexArray(va);
+	glBindBuffer(GL_ARRAY_BUFFER, b);
+	glUniform3fv(colourLoc, 1, glm::value_ptr(colour));
+	glUniform1f(kqLoc, kq);
+	glUniform1f(arcLoc, arc);
+	glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(glm::vec3), glm::value_ptr(position));
+	glBufferSubData(GL_ARRAY_BUFFER, sizeof(glm::vec3), sizeof(glm::vec3), glm::value_ptr(direction));
+	glDrawArrays(GL_POINTS, 0, 1);
+}
diff --git a/gfx/gl/sceneShader.h b/gfx/gl/sceneShader.h
index 9db6ebf..ed1bb79 100644
--- a/gfx/gl/sceneShader.h
+++ b/gfx/gl/sceneShader.h
@@ -61,6 +61,21 @@ class SceneShader {
 		glBuffer b;
 	};
 
+	class SpotLightShader : public SceneProgram {
+	public:
+		SpotLightShader();
+
+		void add(const glm::vec3 & position, const glm::vec3 & direction, const glm::vec3 & colour, const float kq,
+				const float arc) const;
+
+	private:
+		UniformLocation colourLoc;
+		UniformLocation kqLoc;
+		UniformLocation arcLoc;
+		glVertexArray va;
+		glBuffer b;
+	};
+
 public:
 	SceneShader();
 
@@ -68,6 +83,7 @@ public:
 	WaterProgram water;
 	AbsolutePosProgram landmass, absolute;
 	PointLightShader pointLight;
+	SpotLightShader spotLight;
 
 	void setViewProjection(const glm::mat4 & viewProjection) const;
 	void setViewPort(const glm::ivec4 & viewPort) const;
diff --git a/gfx/gl/shaders/spotLight.fs b/gfx/gl/shaders/spotLight.fs
new file mode 100644
index 0000000..add86fd
--- /dev/null
+++ b/gfx/gl/shaders/spotLight.fs
@@ -0,0 +1,34 @@
+#version 330 core
+#extension GL_ARB_shading_language_420pack : enable
+
+out vec3 FragColor;
+
+layout(binding = 0) uniform sampler2D gPosition;
+layout(binding = 1) uniform sampler2D gNormal;
+uniform ivec4 viewPort;
+uniform vec3 colour;
+uniform float kq;
+in vec4 geo_centre;
+in vec4 geo_direction;
+
+void
+main()
+{
+	const vec2 texCoord = gl_FragCoord.xy / viewPort.zw;
+	const vec3 position = texture(gPosition, texCoord).xyz;
+	const vec3 lightv = position - geo_centre.xyz;
+	const float lightDist = length(lightv);
+	if (lightDist > geo_centre.w) {
+		discard;
+	}
+	const vec3 lightDirection = normalize(lightv);
+	if (dot(lightDirection, geo_direction.xyz) < geo_direction.w) {
+		discard;
+	}
+	const vec3 normal = texture(gNormal, texCoord).xyz;
+	const float normalDot = dot(-lightDirection, normal);
+	if (normalDot < 0) {
+		discard;
+	}
+	FragColor = (colour * normalDot) / (1 + (kq * pow(lightDist, 2)));
+}
diff --git a/gfx/gl/shaders/spotLight.gs b/gfx/gl/shaders/spotLight.gs
new file mode 100644
index 0000000..ad65675
--- /dev/null
+++ b/gfx/gl/shaders/spotLight.gs
@@ -0,0 +1,63 @@
+#version 330 core
+#extension GL_ARB_enhanced_layouts : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+const vec3[] pyramid = vec3[]( // four-sided
+		vec3(0, 0, 0), // Apex
+		vec3(-1, 1, 1), // Back-left
+		vec3(-1, -1, 1), // Front-left
+		vec3(1, 1, 1), // Back-right
+		vec3(1, -1, 1) // Front-right
+);
+uniform mat4 viewProjection;
+uniform float arc;
+
+in vec3 position[];
+in vec3 direction[];
+in float size[];
+in float cosarc[];
+layout(points) in;
+
+layout(triangle_strip, max_vertices = 8) out;
+out vec4 geo_centre;
+out vec4 geo_direction;
+
+vec3
+perp(vec3 a)
+{
+	return normalize(a.x != 0  ? vec3((a.y + a.z) / -a.x, 1, 1)
+					: a.y != 0 ? vec3(1, (a.x + a.z) / -a.y, 1)
+							   : vec3(1, 1, (a.x + a.y) / -a.z));
+}
+
+void
+doVertex(vec4 ndcpos)
+{
+	gl_Position = ndcpos;
+	geo_centre = vec4(position[0], size[0]);
+	geo_direction = vec4(direction[0], cosarc[0]);
+	EmitVertex();
+}
+
+void
+main()
+{
+	const float base = size[0] * tan(arc / 2);
+	const vec3 offx = perp(direction[0]);
+	const vec3 offy = cross(direction[0], offx);
+	vec4 out_py[pyramid.length()];
+	for (int i = 0; i < pyramid.length(); ++i) {
+		const vec3 p = pyramid[i];
+		const vec3 edge = (offx * base * p.x) + (offy * base * p.y) + (direction[0] * size[0] * p.z);
+		out_py[i] = viewProjection * (gl_in[0].gl_Position + vec4(edge, 1));
+	}
+	doVertex(out_py[3]);
+	doVertex(out_py[0]);
+	doVertex(out_py[1]);
+	doVertex(out_py[2]);
+	doVertex(out_py[3]);
+	doVertex(out_py[4]);
+	doVertex(out_py[0]);
+	doVertex(out_py[2]);
+	EndPrimitive();
+}
diff --git a/gfx/gl/shaders/spotLight.vs b/gfx/gl/shaders/spotLight.vs
new file mode 100644
index 0000000..e648553
--- /dev/null
+++ b/gfx/gl/shaders/spotLight.vs
@@ -0,0 +1,23 @@
+#version 330 core
+
+layout(location = 0) in vec3 v_position;
+layout(location = 1) in vec3 v_direction;
+
+uniform vec3 colour;
+uniform float kq;
+uniform float arc;
+
+out vec3 position;
+out vec3 direction;
+out float size;
+out float cosarc;
+
+void
+main()
+{
+	position = v_position;
+	direction = normalize(v_direction);
+	size = (8 * sqrt(max(max(colour.r, colour.g), colour.b))) / sqrt(kq);
+	cosarc = cos(arc / 2);
+	gl_Position = vec4(position, 0);
+}