Add rendering support for point lights

5 files changed, 133 insertions, 2 deletions

diff --git a/gfx/gl/sceneShader.cpp b/gfx/gl/sceneShader.cpp
index 0b0c530..a02d955 100644
--- a/gfx/gl/sceneShader.cpp
+++ b/gfx/gl/sceneShader.cpp
@@ -2,9 +2,12 @@
 #include <array>
 #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-waterShader.h>
+#include <gfx/gl/shaders/gs-pointLight.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-waterShader.h>
 #include <glm/gtc/type_ptr.hpp>
 #include <glm/gtx/transform.hpp>
@@ -19,7 +22,7 @@ SceneShader::SceneShader() :
 void
 SceneShader::setViewProjection(const glm::mat4 & viewProjection) const
 {
-	for (const auto & prog : std::array<const SceneProgram *, 4> {&basic, &water, &landmass, &absolute}) {
+	for (const auto & prog : std::array<const SceneProgram *, 5> {&basic, &water, &landmass, &absolute, &pointLight}) {
 		prog->setViewProjection(viewProjection);
 	}
 }
@@ -27,7 +30,7 @@ SceneShader::setViewProjection(const glm::mat4 & viewProjection) const
 void
 SceneShader::setViewPort(const glm::ivec4 & viewPort) const
 {
-	for (const auto & prog : std::array<const SceneProgram *, 4> {&basic, &water, &landmass, &absolute}) {
+	for (const auto & prog : std::array<const SceneProgram *, 5> {&basic, &water, &landmass, &absolute, &pointLight}) {
 		prog->setViewPort(viewPort);
 	}
 }
@@ -73,3 +76,27 @@ SceneShader::WaterProgram::use(float waveCycle) const
 	glm::vec3 waves {waveCycle, 0.F, 0.F};
 	glUniform3fv(waveLoc, 1, glm::value_ptr(waves));
 }
+
+SceneShader::PointLightShader::PointLightShader() :
+	SceneProgram {pointLight_vs, pointLight_gs, pointLight_fs}, colourLoc {*this, "colour"}, kqLoc {*this, "kq"}
+{
+	glBindVertexArray(va);
+	glBindBuffer(GL_ARRAY_BUFFER, b);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec3), nullptr, GL_DYNAMIC_DRAW);
+	glEnableVertexAttribArray(0);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(glm::vec3), nullptr);
+	glBindBuffer(GL_ARRAY_BUFFER, 0);
+	glBindVertexArray(0);
+}
+
+void
+SceneShader::PointLightShader::add(const glm::vec3 & position, const glm::vec3 & colour, const float kq) const
+{
+	Program::use();
+	glBindVertexArray(va);
+	glBindBuffer(GL_ARRAY_BUFFER, b);
+	glUniform3fv(colourLoc, 1, glm::value_ptr(colour));
+	glUniform1f(kqLoc, kq);
+	glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(glm::vec3), glm::value_ptr(position));
+	glDrawArrays(GL_POINTS, 0, 1);
+}
diff --git a/gfx/gl/sceneShader.h b/gfx/gl/sceneShader.h
index 99431f1..62df9bf 100644
--- a/gfx/gl/sceneShader.h
+++ b/gfx/gl/sceneShader.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "program.h"
+#include <glArrays.h>
 
 class Location;
 
@@ -47,12 +48,26 @@ class SceneShader {
 		RequiredUniformLocation waveLoc;
 	};
 
+	class PointLightShader : public SceneProgram {
+	public:
+		PointLightShader();
+
+		void add(const glm::vec3 & position, const glm::vec3 & colour, const float kq) const;
+
+	private:
+		UniformLocation colourLoc;
+		UniformLocation kqLoc;
+		glVertexArray va;
+		glBuffer b;
+	};
+
 public:
 	SceneShader();
 
 	BasicProgram basic;
 	WaterProgram water;
 	AbsolutePosProgram landmass, absolute;
+	PointLightShader pointLight;
 
 	void setViewProjection(const glm::mat4 & viewProjection) const;
 	void setViewPort(const glm::ivec4 & viewPort) const;
diff --git a/gfx/gl/shaders/pointLight.fs b/gfx/gl/shaders/pointLight.fs
new file mode 100644
index 0000000..18407fe
--- /dev/null
+++ b/gfx/gl/shaders/pointLight.fs
@@ -0,0 +1,27 @@
+#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 vec3 geo_centre;
+
+void
+main()
+{
+	const vec2 texCoord = gl_FragCoord.xy / viewPort.zw;
+	const vec3 position = texture(gPosition, texCoord).xyz;
+	const vec3 normal = texture(gNormal, texCoord).xyz;
+	const vec3 lightv = position - geo_centre;
+	const float lightDist = length(lightv);
+	const vec3 lightDirection = normalize(lightv);
+	const float normalDot = dot(-lightDirection, normal);
+	if (normalDot < 0) {
+		discard;
+	}
+	FragColor = (colour * normalDot) / (1 + (kq * pow(lightDist, 2)));
+}
diff --git a/gfx/gl/shaders/pointLight.gs b/gfx/gl/shaders/pointLight.gs
new file mode 100644
index 0000000..2bd71e9
--- /dev/null
+++ b/gfx/gl/shaders/pointLight.gs
@@ -0,0 +1,44 @@
+#version 330 core
+#extension GL_ARB_enhanced_layouts : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+const int maxv = 128;
+const int maxarcs = (maxv / 2) - 1;
+const int minarcs = 10;
+const float tau = radians(360);
+const float scale = 150;
+uniform ivec4 viewPort;
+
+in vec3 centre[];
+in float size[];
+layout(points) in;
+
+layout(triangle_strip, max_vertices = maxv) out;
+out vec3 geo_centre;
+
+void
+doSeg(float arc, vec2 radius)
+{
+	gl_Position = gl_in[0].gl_Position;
+	geo_centre = centre[0];
+	EmitVertex();
+
+	const vec2 off = vec2(cos(arc), sin(arc)) * radius;
+	gl_Position.xy = gl_in[0].gl_Position.xy + off;
+	geo_centre = centre[0];
+	EmitVertex();
+}
+
+void
+main()
+{
+	const vec2 display = viewPort.zw;
+	const vec2 ratio = vec2(1, display.x / display.y);
+	const vec2 radius = (size[0] * ratio * scale) / gl_in[0].gl_Position.w;
+	const float step = tau / clamp(radius.x, minarcs, maxarcs);
+	for (float arc = 0; arc < tau; arc += step) {
+		doSeg(arc, radius);
+	}
+	doSeg(tau, radius);
+	EndPrimitive();
+}
diff --git a/gfx/gl/shaders/pointLight.vs b/gfx/gl/shaders/pointLight.vs
new file mode 100644
index 0000000..6236c33
--- /dev/null
+++ b/gfx/gl/shaders/pointLight.vs
@@ -0,0 +1,18 @@
+#version 330 core
+
+layout(location = 0) in vec3 position;
+
+uniform vec3 colour;
+uniform float kq;
+uniform mat4 viewProjection;
+
+out vec3 centre;
+out float size;
+
+void
+main()
+{
+	centre = position;
+	size = sqrt(256 * max(max(colour.r, colour.g), colour.b) / kq);
+	gl_Position = viewProjection * vec4(centre, 1);
+}