1 files changed, 90 insertions, 0 deletions
diff --git a/gfx/gl/billboardPainter.cpp b/gfx/gl/billboardPainter.cpp
new file mode 100644
index 0000000..878e950
--- /dev/null
+++ b/gfx/gl/billboardPainter.cpp
@@ -0,0 +1,90 @@
+#include "billboardPainter.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}, angle {}, 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 Angle newAngle, const glm::mat4 & newView)
+{
+	angle = newAngle;
+	view = newView;
+}
+
+Angle
+BillboardPainter::getAngle() const
+{
+	return angle;
+}
+
+void
+BillboardPainter::configureBillBoardTextures(glTextures<GL_TEXTURE_2D_ARRAY, 3> & textures, ImageDimensions size)
+{
+	glDebugScope _ {0};
+	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+
+	const auto configuregdata = [size](Impl::glTexture<GL_TEXTURE_2D_ARRAY> & texture, const GLenum iformat) {
+		texture.storage(1, iformat, size || VIEW_ANGLES<GLsizei>);
+		texture.parameter(GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+		texture.parameter(GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+		texture.parameter(GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+		texture.parameter(GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	};
+	configuregdata(textures[0], GL_DEPTH_COMPONENT16);
+	configuregdata(textures[1], GL_RGB8_SNORM);
+	configuregdata(textures[2], GL_RGB5_A1);
+}
+
+void
+BillboardPainter::renderBillBoard(const glTextures<GL_TEXTURE_2D_ARRAY, 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);
+	fbo.texture(GL_DEPTH_ATTACHMENT, billboard[0]);
+	fbo.texture(GL_COLOR_ATTACHMENT0, billboard[1]);
+	fbo.texture(GL_COLOR_ATTACHMENT1, billboard[2]);
+	fbo.assertComplete();
+	if (texture) {
+		texture->bind(0);
+	}
+	glUseProgram(program);
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+	const TextureDimensions billboardSize = billboard[0].getSize();
+	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();
+}