From 36de884ffd09de16006db5ee428426bedf960564 Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Fri, 1 Aug 2014 16:55:03 -0600 Subject: [PATCH] st/mesa: adjust Z coordinates for quad clearing Specify the quad's Z position in clip coordinate space, not normalized Z space. Use viewport scale, translation = 0.5, 0.5. Before, we were specifying the quad's Z position in [0,1] and using viewport scale=1.0, translate=0.0. That works fine, unless your driver needs to work in clip coordinate space and needs to reconstruct viewport near/far values from the scale/translation factors. The VMware svga driver falls into that category. When we did that reconstruction we wound up with near=-1 and far=1 which are outside the limits of [0,1]. In some cases, this caused the quad to be drawn at the wrong depth. In other cases it was clipped away. Fixes some scissored depth clears with VMware driver. This should have no effect on other drivers. We're already using these values for the glBitmap and glDraw/CopyPixels code. Reviewed-by: Roland Scheidegger --- src/mesa/state_tracker/st_cb_clear.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/src/mesa/state_tracker/st_cb_clear.c b/src/mesa/state_tracker/st_cb_clear.c index 4bfa8d75aa9..2c1414e480e 100644 --- a/src/mesa/state_tracker/st_cb_clear.c +++ b/src/mesa/state_tracker/st_cb_clear.c @@ -173,6 +173,9 @@ draw_quad(struct st_context *st, return; } + /* Convert Z from [0,1] to [-1,1] range */ + z = z * 2.0f - 1.0f; + /* positions */ vertices[0][0][0] = x0; vertices[0][0][1] = y0; @@ -319,11 +322,11 @@ clear_with_quad(struct gl_context *ctx, unsigned clear_buffers) struct pipe_viewport_state vp; vp.scale[0] = 0.5f * fb_width; vp.scale[1] = fb_height * (invert ? -0.5f : 0.5f); - vp.scale[2] = 1.0f; + vp.scale[2] = 0.5f; vp.scale[3] = 1.0f; vp.translate[0] = 0.5f * fb_width; vp.translate[1] = 0.5f * fb_height; - vp.translate[2] = 0.0f; + vp.translate[2] = 0.5f; vp.translate[3] = 0.0f; cso_set_viewport(st->cso_context, &vp); } -- 2.30.2