1 files changed, 77 insertions, 0 deletions
diff --git a/gfx/gl/shadowStenciller.cpp b/gfx/gl/shadowStenciller.cpp
new file mode 100644
index 0000000..da2b3a0
--- /dev/null
+++ b/gfx/gl/shadowStenciller.cpp
@@ -0,0 +1,77 @@
+#include "shadowStenciller.h"
+#include "gfx/gl/program.h"
+#include "gfx/gl/shaders/fs-shadowStencil.h"
+#include "gfx/gl/shaders/gs-shadowStencil.h"
+#include "gfx/gl/shaders/vs-shadowStencil.h"
+#include "gfx/models/mesh.h"
+#include "glArrays.h"
+#include "gl_traits.h"
+#include "maths.h"
+#include <stdexcept>
+
+namespace {
+	static constexpr std::array<float, 8> anglesEigthPi {-3, -2, -1, 0, 1, 2, 3, 4};
+	static const auto angles = anglesEigthPi * [](auto ep) {
+		return rotate_yaw(ep * quarter_pi);
+	};
+}
+
+ShadowStenciller::ShadowStenciller() :
+	shadowCaster {shadowStencil_vs, shadowStencil_gs, shadowStencil_fs}, viewProjections {}
+{
+	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+	glDrawBuffer(GL_NONE);
+	glReadBuffer(GL_NONE);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+}
+
+void
+ShadowStenciller::setLightDirection(const Direction3D & lightDir, const Direction3D & lightDirUp)
+{
+	lightDirMat = glm::lookAt(-lightDir, {}, lightDirUp);
+	viewProjections = angles * [this](const auto & a) {
+		return lightDirMat * a;
+	};
+}
+
+glTexture
+ShadowStenciller::createStencilTexture(GLsizei width, GLsizei height)
+{
+	glTexture stencil;
+	glBindTexture(GL_TEXTURE_2D_ARRAY, stencil);
+	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+
+	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, GL_DEPTH_COMPONENT, width, height, 8, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE,
+			nullptr);
+
+	return stencil;
+}
+
+void
+ShadowStenciller::renderStencil(const glTexture & stencil, const MeshBase & mesh, const Texture::AnyPtr texture) const
+{
+	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+	glFramebufferTexture(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, stencil, 0);
+	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
+		throw std::runtime_error("Stencil framebuffer not complete!");
+	}
+	if (texture) {
+		texture->bind();
+	}
+	glUseProgram(shadowCaster);
+	glClear(GL_DEPTH_BUFFER_BIT);
+	glViewport(0, 0, 256, 256);
+	const auto & centre = mesh.getDimensions().centre;
+	const auto & size = mesh.getDimensions().size;
+	const auto extentsMat
+			= glm::translate(glm::ortho(-size, size, -size, size, -size, size), {-centre.x, -centre.z, -centre.y});
+	glUniform(viewProjectionLoc, std::span<const glm::mat4> {viewProjections * [&](const auto & vp) {
+		return extentsMat * vp;
+	}});
+	mesh.Draw();
+}