diff options
| -rw-r--r-- | src/mesa/vbo/vbo_attrib_tmp.h | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/src/mesa/vbo/vbo_attrib_tmp.h b/src/mesa/vbo/vbo_attrib_tmp.h index d305b4add98..47f240c61bd 100644 --- a/src/mesa/vbo/vbo_attrib_tmp.h +++ b/src/mesa/vbo/vbo_attrib_tmp.h @@ -117,14 +117,50 @@ static inline float conv_i10_to_norm_float(const struct gl_context *ctx, int i10 { struct attr_bits_10 val; val.x = i10; - return (2.0F * (float)val.x + 1.0F) * (1.0F / 1023.0F); + + /* Traditionally, OpenGL has had two equations for converting from + * normalized fixed-point data to floating-point data. In the OpenGL 3.2 + * specification, these are equations 2.2 and 2.3, respectively: + * + * f = (2c + 1)/(2^b - 1). (2.2) + * + * Comments below this equation state: "In general, this representation is + * used for signed normalized fixed-point parameters in GL commands, such + * as vertex attribute values." Which is what we're doing here. + * + * f = max{c/(2^(b-1) - 1), -1.0} (2.3) + * + * Comments below this equation state: "In general, this representation is + * used for signed normalized fixed-point texture or floating point values." + * + * OpenGL 4.2+ and ES 3.0 remedy this and state that equation 2.3 (above) + * is used in every case. They remove equation 2.2 completely. + */ + if (_mesa_is_gles3(ctx) || + (ctx->API == API_OPENGL_CORE && ctx->Version >= 42)) { + /* Equation 2.3 above. */ + float f = ((float) val.x) / 511.0F; + return MAX2(f, -1.0); + } else { + /* Equation 2.2 above. */ + return (2.0F * (float)val.x + 1.0F) * (1.0F / 1023.0F); + } } static inline float conv_i2_to_norm_float(const struct gl_context *ctx, int i2) { struct attr_bits_2 val; val.x = i2; - return (2.0F * (float)val.x + 1.0F) * (1.0F / 3.0F); + + if (_mesa_is_gles3(ctx) || + (ctx->API == API_OPENGL_CORE && ctx->Version >= 42)) { + /* Equation 2.3 above. */ + float f = (float) val.x; + return MAX2(f, -1.0); + } else { + /* Equation 2.2 above. */ + return (2.0F * (float)val.x + 1.0F) * (1.0F / 3.0F); + } } #define ATTRI10_1( A, I10 ) ATTR( A, 1, GL_FLOAT, conv_i10_to_i((I10) & 0x3ff), 0, 0, 1 ) |