1 files changed, 74 insertions, 0 deletions
diff --git a/gfx/gl/shadowStenciller.cpp b/gfx/gl/shadowStenciller.cpp
new file mode 100644
index 0000000..86b77e4
--- /dev/null
+++ b/gfx/gl/shadowStenciller.cpp
@@ -0,0 +1,74 @@
+#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/lightDirection.h"
+#include "gfx/models/mesh.h"
+#include "glArrays.h"
+#include "gl_traits.h"
+#include "maths.h"
+#include <stdexcept>
+
+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 LightDirection & lightDir)
+{
+	viewProjections = [&lightDir]<GLint... Ep>(std::integer_sequence<GLint, Ep...>) {
+		constexpr float STEP = two_pi / STENCIL_ANGLES<decltype(two_pi)>;
+		return std::array {rotate_pitch<4>(half_pi - lightDir.position().y)
+				* rotate_yaw<4>((Ep * STEP) - lightDir.position().x)...};
+	}(std::make_integer_sequence<GLint, STENCIL_ANGLES<GLint>>());
+}
+
+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, STENCIL_ANGLES<GLint>, 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);
+	const auto stencilSize = Texture::getSize(stencil);
+	glViewport(0, 0, stencilSize.x, stencilSize.y);
+	const auto & centre = mesh.getDimensions().centre;
+	const auto & size = mesh.getDimensions().size;
+	glUniform(viewProjectionLoc,
+			std::span<const glm::mat4> {viewProjections *
+					[extentsMat = glm::translate(glm::ortho(-size, size, -size, size, -size, size), -centre)](
+							const auto & viewProjection) {
+						return viewProjection * extentsMat;
+					}});
+	mesh.Draw();
+}