Support for the BillboardPainter

Based on the ShadowStenciller, creates flattened images of a model for
simplified mass use in a scene.

10 files changed, 216 insertions, 0 deletions

diff --git a/gfx/frustum.h b/gfx/frustum.h
index cd4cbe1..5b7947b 100644
--- a/gfx/frustum.h
+++ b/gfx/frustum.h
@@ -17,6 +17,12 @@ public:
 	}
 
 	[[nodiscard]] auto &
+	getView() const
+	{
+		return view;
+	}
+
+	[[nodiscard]] auto &
 	getViewProjection() const
 	{
 		return viewProjection;
diff --git a/gfx/gl/billboardPainter.cpp b/gfx/gl/billboardPainter.cpp
new file mode 100644
index 0000000..e72e72d
--- /dev/null
+++ b/gfx/gl/billboardPainter.cpp
@@ -0,0 +1,92 @@
+#include "billboardPainter.h"
+#include "gfx/models/mesh.h"
+#include "glArrays.h"
+#include "gl_traits.h"
+#include "gldebug.h"
+#include "maths.h"
+#include <gfx/gl/shaders/billboardPainter-frag.h>
+#include <gfx/gl/shaders/billboardPainter-geom.h>
+#include <gfx/gl/shaders/billboardPainter-vert.h>
+#include <stdexcept>
+
+const auto VIEWS = []<GLint... Ep>(std::integer_sequence<GLint, Ep...>) {
+	constexpr float STEP = two_pi / BillboardPainter::VIEW_ANGLES<decltype(two_pi)>;
+	return std::array {rotate_yaw<4>(Ep * STEP)...};
+}(std::make_integer_sequence<GLint, BillboardPainter::VIEW_ANGLES<GLint>>());
+
+BillboardPainter::BillboardPainter() :
+	program {billboardPainter_vert, billboardPainter_geom, billboardPainter_frag}, view {}
+{
+	glDebugScope _ {fbo};
+	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+	static constexpr std::array<GLenum, 2> ATTACHMENTS {GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1};
+	glDrawBuffers(ATTACHMENTS.size(), ATTACHMENTS.data());
+	glReadBuffer(GL_NONE);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+	glUseProgram(program);
+	glUniform(viewLoc, std::span<const glm::mat4> {VIEWS});
+}
+
+void
+BillboardPainter::setView(const glm::mat4 & newView)
+{
+	view = newView;
+}
+
+glTextures<3>
+BillboardPainter::createBillBoardTextures(GLsizei width, GLsizei height)
+{
+	glDebugScope _ {0};
+	glTextures<3> textures;
+	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+
+	const auto configuregdata = [width, height](const GLuint texture, const GLint iformat, const GLenum format) {
+		glBindTexture(GL_TEXTURE_2D_ARRAY, texture);
+		glTexParameter(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+		glTexParameter(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+		glTexParameter(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+		glTexParameter(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+		glTexImage3D(GL_TEXTURE_2D_ARRAY, 0, iformat, width, height, VIEW_ANGLES<GLint>, 0, format, GL_BYTE, nullptr);
+	};
+	configuregdata(textures[0], GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT);
+	configuregdata(textures[1], GL_RGB8_SNORM, GL_RGB);
+	configuregdata(textures[2], GL_RGB5_A1, GL_RGBA);
+
+	return textures;
+}
+
+void
+BillboardPainter::renderBillBoard(
+		const glTextures<3> & billboard, const MeshBase & mesh, const Texture::AnyPtr texture) const
+{
+	glDebugScope _ {fbo};
+	glEnable(GL_BLEND);
+	glEnable(GL_DEPTH_TEST);
+	glDisable(GL_CULL_FACE);
+	glCullFace(GL_BACK);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+	glClearColor(0, 0, 0, 0);
+	glFramebufferTexture(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, billboard[0], 0);
+	glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, billboard[1], 0);
+	glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, billboard[2], 0);
+	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
+		throw std::runtime_error("Billboard framebuffer not complete!");
+	}
+	if (texture) {
+		texture->bind();
+	}
+	glUseProgram(program);
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+	const TextureDimensions billboardSize = {256, 256, 8}; // Texture::getSize(billboard[0]);
+	glViewport(0, 0, billboardSize.x, billboardSize.y);
+	const auto & centre = mesh.getDimensions().centre;
+	const auto & size = mesh.getDimensions().size;
+	glUniform(viewProjectionLoc,
+			std::span<const glm::mat4> {VIEWS *
+					[extentsMat = glm::translate(glm::ortho(-size, size, -size, size, -size, size), -centre), this](
+							const auto & view) {
+						return this->view * view * extentsMat;
+					}});
+	mesh.Draw();
+}
diff --git a/gfx/gl/billboardPainter.h b/gfx/gl/billboardPainter.h
new file mode 100644
index 0000000..4ce7b10
--- /dev/null
+++ b/gfx/gl/billboardPainter.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include "gfx/gl/program.h"
+#include "gfx/models/mesh.h"
+#include "gfx/models/texture.h"
+#include "glArrays.h"
+
+class LightDirection;
+
+class BillboardPainter {
+public:
+	template<typename T> static constexpr T VIEW_ANGLES = 8;
+
+	BillboardPainter();
+
+	[[nodiscard]]
+	static glTextures<3> createBillBoardTextures(GLsizei width, GLsizei height);
+	void setView(const glm::mat4 &);
+	void renderBillBoard(const glTextures<3> &, const MeshBase &, Texture::AnyPtr texture) const;
+
+private:
+	glFrameBuffer fbo;
+	Program program;
+	Program::RequiredUniformLocation viewProjectionLoc {program, "viewProjection"};
+	Program::RequiredUniformLocation viewLoc {program, "view"};
+
+	glm::mat4 view;
+};
diff --git a/gfx/gl/sceneRenderer.cpp b/gfx/gl/sceneRenderer.cpp
index c1ec987..463ee8a 100644
--- a/gfx/gl/sceneRenderer.cpp
+++ b/gfx/gl/sceneRenderer.cpp
@@ -83,8 +83,10 @@ SceneRenderer::preFrame(const SceneProvider & scene, const LightDirection lightD
 {
 	glDebugScope _ {output};
 	const auto lightView = shadowMapper.preFrame(lightDirection, camera);
+	billboardPainter.setView(camera.getView());
 	scene.forEachRenderable([&lightView, this](Renderable * renderable) {
 		renderable->preFrame(camera, lightView);
+		renderable->updateBillboard(billboardPainter);
 	});
 }
 
diff --git a/gfx/gl/sceneRenderer.h b/gfx/gl/sceneRenderer.h
index d6f5dd1..a7f7770 100644
--- a/gfx/gl/sceneRenderer.h
+++ b/gfx/gl/sceneRenderer.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "billboardPainter.h"
 #include "gfx/lightDirection.h"
 #include "glArrays.h"
 #include "gldebug.h"
@@ -62,4 +63,5 @@ protected:
 	glBuffer displayVBO;
 	SceneShader shader;
 	ShadowMapper shadowMapper;
+	BillboardPainter billboardPainter;
 };
diff --git a/gfx/gl/shaders/billboardPainter.frag b/gfx/gl/shaders/billboardPainter.frag
new file mode 100644
index 0000000..354f2ab
--- /dev/null
+++ b/gfx/gl/shaders/billboardPainter.frag
@@ -0,0 +1,22 @@
+#version 460 core
+
+layout(binding = 0) uniform sampler2D textureAlbedo;
+layout(location = 0) out vec4 bNormal;
+layout(location = 1) out vec4 bAlbedoSpec;
+
+include(`materialDetail.glsl')
+include(`materialCommon.glsl')
+in vec2 gTexCoords;
+in vec3 gNormal;
+in vec4 gColour;
+flat in MaterialDetail gMaterial;
+
+void
+main()
+{
+	vec4 textureColour = getTextureColour(gMaterial, gTexCoords);
+	float opaque = step(0.5, mix(textureColour.a, 1, gColour.a));
+	bNormal = vec4(gNormal, opaque);
+	gl_FragDepth = mix(1.0, gl_FragCoord.z, opaque);
+	bAlbedoSpec = mix(textureColour, vec4(gColour.rgb, 1), gColour.a);
+}
diff --git a/gfx/gl/shaders/billboardPainter.geom b/gfx/gl/shaders/billboardPainter.geom
new file mode 100644
index 0000000..abd5f83
--- /dev/null
+++ b/gfx/gl/shaders/billboardPainter.geom
@@ -0,0 +1,34 @@
+#version 460 core
+
+include(`materialDetail.glsl')
+
+layout(triangles) in;
+layout(triangle_strip, max_vertices = 24) out;
+
+uniform mat4 viewProjection[8];
+uniform mat4 view[8];
+in vec3 FragPos[];
+in vec2 TexCoords[];
+flat in MaterialDetail Material[];
+in vec3 Normal[];
+in vec4 Colour[];
+out vec2 gTexCoords;
+out vec3 gNormal;
+out vec4 gColour;
+flat out MaterialDetail gMaterial;
+
+void
+main()
+{
+	for (gl_Layer = 0; gl_Layer < viewProjection.length(); ++gl_Layer) {
+		for (int v = 0; v < FragPos.length(); ++v) {
+			gl_Position = viewProjection[gl_Layer] * vec4(FragPos[v], 1);
+			gNormal = (view[gl_Layer] * vec4(Normal[v], 1)).xyz;
+			gTexCoords = TexCoords[v];
+			gMaterial = Material[v];
+			gColour = Colour[v];
+			EmitVertex();
+		}
+		EndPrimitive();
+	}
+}
diff --git a/gfx/gl/shaders/billboardPainter.vert b/gfx/gl/shaders/billboardPainter.vert
new file mode 100644
index 0000000..d7c1219
--- /dev/null
+++ b/gfx/gl/shaders/billboardPainter.vert
@@ -0,0 +1,23 @@
+#version 460 core
+
+layout(binding = 1) uniform usampler2DRect materialData;
+
+include(`meshIn.glsl')
+include(`materialDetail.glsl')
+include(`getMaterialDetail.glsl')
+
+out vec3 FragPos;
+out vec2 TexCoords;
+flat out MaterialDetail Material;
+out vec3 Normal;
+out vec4 Colour;
+
+void
+main()
+{
+	TexCoords = texCoord;
+	Material = getMaterialDetail(material);
+	FragPos = position;
+	Colour = colour;
+	Normal = normal;
+}
diff --git a/gfx/renderable.cpp b/gfx/renderable.cpp
index 9fbc85b..8caab93 100644
--- a/gfx/renderable.cpp
+++ b/gfx/renderable.cpp
@@ -19,3 +19,8 @@ void
 Renderable::updateStencil(const ShadowStenciller &) const
 {
 }
+
+void
+Renderable::updateBillboard(const BillboardPainter &) const
+{
+}
diff --git a/gfx/renderable.h b/gfx/renderable.h
index ea72bb6..d0870ad 100644
--- a/gfx/renderable.h
+++ b/gfx/renderable.h
@@ -6,6 +6,7 @@ class SceneShader;
 class Frustum;
 class ShadowMapper;
 class ShadowStenciller;
+class BillboardPainter;
 
 class Renderable {
 public:
@@ -19,4 +20,5 @@ public:
 	virtual void shadows(const ShadowMapper & shadowMapper, const Frustum &) const;
 
 	virtual void updateStencil(const ShadowStenciller & lightDir) const;
+	virtual void updateBillboard(const BillboardPainter &) const;
 };