Merge pull request #16 from omnisci3nce/port-opengl-ral

Bring back OpenGL (part 1)

1 files changed, 73 insertions, 0 deletions

diff --git a/src/renderer/backends/opengl/opengl_helpers.h b/src/renderer/backends/opengl/opengl_helpers.h
new file mode 100644
index 0000000..a3c4014
--- /dev/null
+++ b/src/renderer/backends/opengl/opengl_helpers.h
@@ -0,0 +1,73 @@
+#if defined(CEL_REND_BACKEND_OPENGL)
+#pragma once
+#include "backend_opengl.h"
+#include "log.h"
+#include "ral.h"
+#include "ral_types.h"
+
+#include <glad/glad.h>
+#include <glfw3.h>
+#include "ral_types.h"
+typedef struct opengl_vertex_attr {
+  u32 count;
+  GLenum data_type;
+} opengl_vertex_attr;
+
+static opengl_vertex_attr format_from_vertex_attr(vertex_attrib_type attr) {
+  switch (attr) {
+    case ATTR_F32:
+      return (opengl_vertex_attr){ .count = 1, .data_type = GL_FLOAT };
+    case ATTR_U32:
+      return (opengl_vertex_attr){ .count = 1, .data_type = GL_UNSIGNED_INT };
+    case ATTR_I32:
+      return (opengl_vertex_attr){ .count = 1, .data_type = GL_INT };
+    case ATTR_F32x2:
+      return (opengl_vertex_attr){ .count = 2, .data_type = GL_FLOAT };
+    case ATTR_U32x2:
+      // return VK_FORMAT_R32G32_UINT;
+    case ATTR_I32x2:
+      // return VK_FORMAT_R32G32_UINT;
+    case ATTR_F32x3:
+      return (opengl_vertex_attr){ .count = 3, .data_type = GL_FLOAT };
+    case ATTR_U32x3:
+      // return VK_FORMAT_R32G32B32_UINT;
+    case ATTR_I32x3:
+      // return VK_FORMAT_R32G32B32_SINT;
+    case ATTR_F32x4:
+      return (opengl_vertex_attr){ .count = 4, .data_type = GL_FLOAT };
+    case ATTR_U32x4:
+      // return VK_FORMAT_R32G32B32A32_UINT;
+    case ATTR_I32x4:
+      return (opengl_vertex_attr){ .count = 4, .data_type = GL_INT };
+  }
+}
+
+static u32 opengl_bindcreate_vao(gpu_buffer* buf, vertex_description desc) {
+  // 1. Bind the buffer
+  glBindBuffer(GL_ARRAY_BUFFER, buf->id.vbo);
+  // 2. Create new VAO
+  u32 vao;
+  glGenVertexArrays(1, &vao);
+  glBindVertexArray(vao);
+
+  // Attributes
+  u32 attr_count = desc.attributes_count;
+  printf("N attributes %d\n", attr_count);
+  u64 offset = 0;
+  size_t vertex_size = desc.use_full_vertex_size ? sizeof(vertex) : desc.stride;
+  for (u32 i = 0; i < desc.attributes_count; i++) {
+    opengl_vertex_attr format = format_from_vertex_attr(desc.attributes[i]);
+    glVertexAttribPointer(i, format.count, format.data_type, GL_FALSE, vertex_size, (void*)offset);
+    TRACE(" %d %d %d %d %d %s", i, format.count, format.data_type, vertex_size, offset,
+          desc.attr_names[i]);
+    glEnableVertexAttribArray(i);  // nth index
+    size_t this_offset = vertex_attrib_size(desc.attributes[i]);
+    printf("offset total %lld this attr %ld\n", offset, this_offset);
+    offset += this_offset;
+  }
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+
+  return vao;
+}
+
+#endif