pioneerspacesim · sturnclaw · Jan 3, 2026 · Feb 24, 2025 · Jan 1, 2026 · Jan 2, 2026
diff --git a/data/shaders/opengl/thruster.frag b/data/shaders/opengl/thruster.frag
@@ -0,0 +1,27 @@
+// Copyright © 2008-2026 Pioneer Developers. See AUTHORS.txt for details
+// Licensed under the terms of the GPL v3. See licenses/GPL-3.txt
+
+#include "attributes.glsl"
+#include "lib.glsl"
+
+uniform sampler2D texture0; //diffuse
+
+in vec2 texCoord0;
+in vec4 flame_color;
+in float ramp;
+
+out vec4 frag_color;
+
+void main(void)
+{
+	vec4 color = texture(texture0, texCoord0);
+	vec3 old_color = color.rgb;
+	color *= flame_color;
+	// generate a light blue flickering glow around the flame
+	float ramp2 = ramp * ramp;
+	color.g += ramp2 * ramp2 * old_color.g;
+	color.r += ramp2 * ramp * old_color.r;
+	color.b += ramp2 * old_color.b;
+
+	frag_color = color;
+}
diff --git a/data/shaders/opengl/thruster.shaderdef b/data/shaders/opengl/thruster.shaderdef
@@ -0,0 +1,12 @@
+## Copyright © 2008-2026 Pioneer Developers. See AUTHORS.txt for details
+## Licensed under the terms of the GPL v3. See licenses/GPL-3.txt
+
+# Basic shader for drawing unlit, possibly textured models that are animated
+
+Shader thruster
+
+Texture sampler2D texture0 name=texture0
+Buffer DrawData binding=1
+
+Vertex "thruster.vert"
+Fragment "thruster.frag"
diff --git a/data/shaders/opengl/thruster.vert b/data/shaders/opengl/thruster.vert
@@ -0,0 +1,46 @@
+// Copyright © 2008-2026 Pioneer Developers. See AUTHORS.txt for details
+// Licensed under the terms of the GPL v3. See licenses/GPL-3.txt
+
+// #extension GL_ARB_gpu_shader5 : enable
+
+#include "attributes.glsl"
+#include "lib.glsl"
+
+out vec2 texCoord0;
+out vec4 flame_color;
+out float ramp;
+
+float map_percentage( float val, float base_percent)
+{
+   return base_percent + val * (1.0 - base_percent);
+}
+
+void main(void)
+{
+	// emission.r is the thruster power setting
+	float thruster_power = material.emission.r;
+	// emission.a is the random flicker value
+	float random = material.emission.a;
+
+	// power setting effects the brightness and opacity of the flame
+	float brightness = map_percentage(thruster_power, 0.25);
+	// flicker should only change the brightness a small amount each frame
+	float flicker = map_percentage(random, 0.95);
+
+	flame_color = material.diffuse * flicker * brightness;
+	// a very light blue flickering glow around flame
+	flame_color.rg *= vec2(flicker);
+
+	// the power setting also controls the length of the flame
+	// flame length can range from 50% to 100%
+	float flame_length = map_percentage(thruster_power, 0.5);
+	// modulate the flame shape using flicker
+	// flame_length only effects the z axis which is the thrust direction
+	vec4 scale = vec4(flicker, flicker, flicker * flame_length, 1.0);
+
+	gl_Position = uViewProjectionMatrix * (a_vertex * scale);
+
+	texCoord0 = a_uv0.xy;
+	// set the blend ramp
+	ramp = a_uv0.y * 0.5;
+}
diff --git a/src/Intro.cpp b/src/Intro.cpp
@@ -160,5 +160,6 @@ void Intro::Draw(float deltaTime)
 		matrix4x4f::Translation(0, 0, m_dist) *
 		matrix4x4f::RotateXMatrix(DEG2RAD(-15.0f)) *
 		matrix4x4f::RotateYMatrix(duration);
+	m_model->SetRenderTime(duration);
 	m_model->Render(trans);
 }
diff --git a/src/ShipCockpit.cpp b/src/ShipCockpit.cpp
@@ -195,6 +195,7 @@ void ShipCockpit::Update(const Player *player, float timeStep)
 		vector3f linthrust{ prop->GetLinThrusterState() };
 		vector3f angthrust{ prop->GetAngThrusterState() };
 		GetModel()->SetThrust(linthrust, -angthrust);
+		GetModel()->SetRenderTime(Pi::game->GetTime());
 	}
 }
 

diff --git a/src/editor/ModelViewerWidget.cpp b/src/editor/ModelViewerWidget.cpp
@@ -578,6 +578,7 @@ void ModelViewerWidget::DrawModel(matrix4x4f trans)
 		(m_options.showGeomBBox ? SceneGraph::Model::DEBUG_GEOMBBOX : 0x0) |
 		(m_options.wireframe ? SceneGraph::Model::DEBUG_WIREFRAME : 0x0));
 
+	m_model->SetRenderTime(GetApp()->GetTime());
 	m_model->Render(m_modelViewMat);
 	m_navLights->Render(m_renderer);
 }

diff --git a/src/scenegraph/Model.h b/src/scenegraph/Model.h
@@ -171,6 +171,7 @@ namespace SceneGraph {
 		Graphics::Renderer *GetRenderer() const { return m_renderer; }
 
 		//special for ship model use
+		void SetRenderTime(const double newRenderTime) { m_renderData.renderTime = newRenderTime; }
 		void SetThrust(const vector3f &linear, const vector3f &angular);
 
 		void SetThrusterColor(const vector3f &dir, const Color &color);

diff --git a/src/scenegraph/Node.h b/src/scenegraph/Node.h
@@ -50,13 +50,15 @@ namespace SceneGraph {
 		Color customColor;
 
 		float boundingRadius; //updated by model and passed to submodels
-		unsigned int nodemask;
+		uint32_t nodemask;
+		double renderTime;
 
 		RenderData() :
 			linthrust(),
 			angthrust(),
 			boundingRadius(0.f),
-			nodemask(NODE_SOLID) //draw solids
+			nodemask(NODE_SOLID), //draw solids
+			renderTime(0.0)
 		{
 		}
 	};

diff --git a/src/scenegraph/Thruster.cpp b/src/scenegraph/Thruster.cpp
@@ -24,12 +24,23 @@ namespace SceneGraph {
 	static const std::string thrusterGlowTextureFilename("textures/halo.dds");
 	static Color baseColor(178, 153, 255, 255);
 
+	uint32_t hash32(uint32_t x)
+	{
+		x ^= x >> 16;
+		x *= 0x21f0aaad;
+		x ^= x >> 15;
+		x *= 0xd35a2d97;
+		x ^= x >> 15;
+		return x;
+	}
+
 	Thruster::Thruster(Graphics::Renderer *r, bool _linear, const vector3f &_pos, const vector3f &_dir) :
 		Node(r, NODE_TRANSPARENT),
 		linearOnly(_linear),
 		dir(_dir),
 		pos(_pos),
-		currentColor(baseColor)
+		currentColor(baseColor),
+		displayedPower(0.f)
 	{
 		//set up materials
 		Graphics::MaterialDescriptor desc;
@@ -43,12 +54,12 @@ namespace SceneGraph {
 
 		auto vtxFormat = Graphics::VertexFormatDesc::FromAttribSet(Graphics::ATTRIB_POSITION | Graphics::ATTRIB_UV0);
 
-		m_tMat.Reset(r->CreateMaterial("unlit", desc, rsd, vtxFormat));
+		m_tMat.Reset(r->CreateMaterial("thruster", desc, rsd, vtxFormat));
 		m_tMat->SetTexture("texture0"_hash,
 			Graphics::TextureBuilder::Billboard(thrusterTextureFilename).GetOrCreateTexture(r, "billboard"));
 		m_tMat->diffuse = baseColor;
 
-		m_glowMat.Reset(r->CreateMaterial("unlit", desc, rsd, vtxFormat));
+		m_glowMat.Reset(r->CreateMaterial("thruster", desc, rsd, vtxFormat));
 		m_glowMat->SetTexture("texture0"_hash,
 			Graphics::TextureBuilder::Billboard(thrusterGlowTextureFilename).GetOrCreateTexture(r, "billboard"));
 		m_glowMat->diffuse = baseColor;
@@ -61,7 +72,8 @@ namespace SceneGraph {
 		linearOnly(thruster.linearOnly),
 		dir(thruster.dir),
 		pos(thruster.pos),
-		currentColor(thruster.currentColor)
+		currentColor(thruster.currentColor),
+		displayedPower(thruster.displayedPower)
 	{
 	}
 
@@ -101,9 +113,32 @@ namespace SceneGraph {
 					power = fabs(at.z);
 			}
 		}
-		if (power < 0.001f) return;
 
-		m_tMat->diffuse = m_glowMat->diffuse = currentColor * power;
+		// fade in/out the amount of thruster power shown
+		displayedPower = MathUtil::Lerp(displayedPower, power, 0.2f);
+		if (displayedPower < 0.01f) {
+			return;
+		}
+
+		// animate the thrust flame using the thruster shader
+		// update animation time on each render
+		// a unique time stamp is needed for each thruster flame to have a unique flicker
+		// use thruster position to make each thruster time different
+		// generate a psuedo random flicker
+		// this could be done in the vertex shader but the value only needs to be
+		// generated once per frame, not for every vertex
+		float hash = pos.x + pos.y + pos.z;
+		hash = (uint16_t(hash32(*reinterpret_cast<uint32_t *>(&hash)) & 0xFFFF)) / 65535.f;
+		const float flicker = abs(sin(static_cast<float>(rd->renderTime) * 55.f * (0.75f + hash * 0.5f)));
+
+		// pass the power setting and flicker value using the material emissive
+		// emissive.a is the flicker value for the flame
+		m_tMat->emissive.a = m_glowMat->emissive.a = flicker * 255.f;
+
+		// emissive.r is the thruster power setting which effects flame length and brightness
+		m_tMat->emissive.r = m_glowMat->emissive.r = 255.0f * displayedPower;
+
+		m_tMat->diffuse = m_glowMat->diffuse = currentColor;
 
 		//directional fade
 		vector3f cdir = vector3f(trans * -dir).Normalized();
@@ -184,18 +219,18 @@ namespace SceneGraph {
 		verts.Clear();
 		{
 			//create glow billboard when looking down the thruster
-			const float w = 0.2;
+			constexpr float w = 0.2f;
 
 			vector3f one(-w, -w, 0.f); //top left
 			vector3f two(-w, w, 0.f);  //top right
 			vector3f three(w, w, 0.f); //bottom right
 			vector3f four(w, -w, 0.f); //bottom left
 
 			//uv coords
-			const vector2f topLeft(0.f, 1.f);
-			const vector2f topRight(1.f, 1.f);
-			const vector2f botLeft(0.f, 0.f);
-			const vector2f botRight(1.f, 0.f);
+			static constexpr vector2f const topLeft(0.f, 1.f);
+			static constexpr vector2f const topRight(1.f, 1.f);
+			static constexpr vector2f const botLeft(0.f, 0.f);
+			static constexpr vector2f const botRight(1.f, 0.f);
 
 			for (int i = 0; i < 5; i++) {
 				verts.Add(one, topLeft);

diff --git a/src/scenegraph/Thruster.h b/src/scenegraph/Thruster.h
@@ -44,6 +44,7 @@ namespace SceneGraph {
 		vector3f dir;
 		vector3f pos;
 		Color currentColor;
+		float displayedPower; // used to fade in/out to power (size) of thruster shown
 	};
 
 } // namespace SceneGraph

diff --git a/src/ship/Propulsion.cpp b/src/ship/Propulsion.cpp
@@ -241,7 +241,10 @@ void Propulsion::Render(Graphics::Renderer *r, const Camera *camera, const vecto
 	 * thruster and so on)... this code is :-/
 	*/
 	//angthrust negated, for some reason
-	if (m_smodel != nullptr) m_smodel->SetThrust(vector3f(GetLinThrusterState()), -vector3f(GetAngThrusterState()));
+	if (m_smodel != nullptr) {
+		m_smodel->SetThrust(vector3f(GetLinThrusterState()), -vector3f(GetAngThrusterState()));
+		m_smodel->SetRenderTime(Pi::game->GetTime());
+	}
 }
 
 void Propulsion::AIModelCoordsMatchSpeedRelTo(const vector3d &v, const DynamicBody *other)

diff --git a/src/vector2.h b/src/vector2.h
@@ -28,7 +28,7 @@ class vector2 {
 	vector2() :
 		x(0.0f),
 		y(0.0f) {}
-	vector2(T _x, T _y) :
+	constexpr vector2(T _x, T _y) :
 		x(_x),
 		y(_y) {}
 	explicit vector2(int v) :