Merge branch '16f-scrsht' into 'master'

render/gles2: produce 16f screencopy data

See merge request wlroots/wlroots!3655

render/gles2/pixel_format.c

@@ -1,6 +1,7 @@
 #include <drm_fourcc.h>
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
+#include <GLES3/gl3.h>
 #include "render/gles2.h"
 
 /*
@@ -150,6 +151,16 @@ const struct wlr_gles2_pixel_format *get_gles2_format_from_drm(uint32_t fmt) {
 
 const struct wlr_gles2_pixel_format *get_gles2_format_from_gl(
 		GLint gl_format, GLint gl_type, bool alpha) {
+	// Mesa may provide GL ES >= 3.0 instead of the minimum asked for 2.0;
+	// in this case, the gl_type associated to render buffers created from
+	// half float DMABUFs _may_ be the value GL_HALF_FLOAT = 0x140b from
+	// GL ES 3.0, not the value GL_HALF_FLOAT_OES = 0x8D61 from GL ES 2.0
+	// extension OES_texture_half_float, which is used to define texture
+	// images for half-float shm buffers.
+	if (gl_type == GL_HALF_FLOAT) {
+		gl_type = GL_HALF_FLOAT_OES;
+	}
+
 	for (size_t i = 0; i < sizeof(formats) / sizeof(*formats); ++i) {
 		if (formats[i].gl_format == gl_format &&
 				formats[i].gl_type == gl_type &&

render/gles2/renderer.c

@@ -467,6 +467,23 @@ static bool gles2_read_pixels(struct wlr_renderer *wlr_renderer,
 
 	push_gles2_debug(renderer);
 
+	// The 16F buffer formats have more than one possible color read
+	// format/type combination; the type can be GL_HALF_FLOAT = 0x140b,
+	// if the GLES implementation version is >= 3.0, or could be
+	// GL_HALF_FLOAT_OES (which would be appropriate at GLES 2.0.)
+	// To match glReadPixels' strict requirements on format+type,
+	// we submit exactly the implementation suggested format and type,
+	// if these are compatible with the drm_format.
+	GLint gl_format = -1, gl_type = -1;
+	glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT, &gl_format);
+	glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE, &gl_type);
+	const struct wlr_gles2_pixel_format *impl_format =
+		get_gles2_format_from_gl(gl_format, gl_type, fmt->has_alpha);
+	if (impl_format != fmt) {
+		gl_format = fmt->gl_format;
+		gl_type = fmt->gl_type;
+	}
+
 	// Make sure any pending drawing is finished before we try to read it
 	glFinish();
 
@@ -479,14 +496,14 @@ static bool gles2_read_pixels(struct wlr_renderer *wlr_renderer,
 		// Under these particular conditions, we can read the pixels with only
 		// one glReadPixels call
 
-		glReadPixels(src_x, src_y, width, height, fmt->gl_format, fmt->gl_type, p);
+		glReadPixels(src_x, src_y, width, height, gl_format, gl_type, p);
 	} else {
 		// Unfortunately GLES2 doesn't support GL_PACK_ROW_LENGTH, so we have to read
 		// the lines out row by row
 		for (size_t i = 0; i < height; ++i) {
 			uint32_t y = src_y + i;
-			glReadPixels(src_x, y, width, 1, fmt->gl_format,
+			glReadPixels(src_x, y, width, 1, gl_format,
-				fmt->gl_type, p + i * stride + dst_x * drm_fmt->bpp / 8);
+				gl_type, p + i * stride + dst_x * drm_fmt->bpp / 8);
 		}
 	}